Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: jayncat on June 28, 2014, 08:34:12 pm
Title: Need Help With Dash A/C Problem .....
Post by: jayncat on June 28, 2014, 08:34:12 pm
Dash Air was blowing warm .... Replaced: Dryer, High side hose from dryer to bottom of compressor, Low pressure switch, High pressure switch, Relay, 20 amp mini breaker under isolator.
Filled system with 7 (12oz cans) of R134
Now dash is blowing cold air, and Blower Motor works, but cycles when compressor does.
High Side Pressure is 150 Low Side Pressure kicks out at 25 and WILL NOT maintain 30-35 suction pressure.
How do I get level return pressure?
What kind of metering system is there, and WHERE is it located?
A friend has been doing all repairs, as I have NO knowledge in this area ...
I sure would appreciate all ideas of possible solutions to correct this situation. We are to travel from N. GA to Indiana next Tuesday ... Cold Dash air ... should would be nice!!!
Thanks All .....
Title: Re: Need Help With Dash A/C Problem .....
Post by: fouroureye on June 28, 2014, 08:41:03 pm
Sounds like you replaced most of system - expansion valve?
There are better experts here than me, but that is what was wrong with my 88.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Peter & Beth on June 28, 2014, 08:47:02 pm
I think your system holds right around five pounds R134a. You may be overcharged. The expansion valve could need to be replaced. Mine was replaced two years ago.
Title: Re: Need Help With Dash A/C Problem .....
Post by: jayncat on June 28, 2014, 09:03:33 pm
I own a 97 U295 40ft. Where is the expansion valve located?????
Thanks for your help ....
Title: Re: Need Help With Dash A/C Problem .....
Post by: OldManSax on June 28, 2014, 09:16:02 pm
I can't help with the exact location but the TXV (expansion valve) will be located very close to the evaporator.
TOM
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on June 29, 2014, 12:29:44 am
On mine, the TXV is up under the dash to the right of the air handler. It's wrapped in pipe insulation and somebody cut the wire ties and uncovered it. I'm not sure what they were doing.
Mine doesn't have a low pressure valve, but appears to have a low temperature sensor on the evaporator coils.
My low side pressures are staying around 20psi and I can see the TXV modulating it. My compressor will stay on most of the time when fan is on high, but cycles on slower speeds.
One thing that always should be checked is good airflow over the evap coils. Dirty air filter, dirty coils, broken ducts, etc will not let good heat transfer occur and the evap coils will get too cold and either lower pressure or cause the "Freeze switch" to cycle the unit.
Mine will blow nice cold 47deg air....and then cycle. It's almost too cold......I think I have to do some cleaning.
Anybody have information on the Dash A/C system or an instruction manual?
Title: Re: Need Help With Dash A/C Problem .....
Post by: Chad and Judy on June 29, 2014, 09:58:11 am
SNIP: On mine, the TXV is up under the dash to the right of the air handler. It's wrapped in pipe insulation and somebody cut the wire ties and uncovered it. I'm not sure what they were doing.
How are you accessing the TXV and the other dash-air hardware in the dash-area? I haven't discovered anything resembling easy access, but it appears you have?
Thanks!!
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on June 29, 2014, 11:15:16 am
I can't speak for your coach, but a solid yank on the top of the "dog house" opens it up. It is hinged along the front side and used those brass spring ball cabinet door latch things to hold it down. Mine was pretty stuck!
I have to flip open the cover on the dash first, as it rests on the cover over top of the doghouse.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Barry & Cindy on June 29, 2014, 11:20:30 pm
We can see our dash air evaporator hose connections & valve bottom left of 12-volt breaker panel in front of co-pilot seat.
Title: Re: Need Help With Dash A/C Problem .....
Post by: pocketchange on June 29, 2014, 11:35:21 pm
Max freon is 80 oz's.
Good Luck, pc
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on June 30, 2014, 10:45:52 am
Two relevant threads with info and pics:
Finally fixed my dash A/C (http://www.foreforums.com/index.php?topic=15329)
Dash Air Intake (http://www.foreforums.com/index.php?topic=21110)
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on June 30, 2014, 11:08:25 am
Also, to get pressures I liked, I put in around 6lbs of r134a. I still need to ensure my evap coils are clean.
Is there a manual or manufacturer information on these dash A/C units?
Title: Re: Need Help With Dash A/C Problem .....
Post by: Bill Chaplin on June 30, 2014, 01:36:26 pm
Is there a manual or manufacturer information on these dash A/C units?
Yes, I second that notion, for the old (1993) unit.
Is the line going from front (evap)to rear ( compressor) a one piece line?
Title: Re: Need Help With Dash A/C Problem .....
Post by: red tractor on June 30, 2014, 08:21:03 pm
If you are talking about the low pressure line the answer is yes, if talking about the high pressure line the answer is no as it goes from the compressor to the condenser and then from the condenser to the expansion valve. On the 93 the condenser is up front behind the grills
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on July 05, 2014, 07:20:16 pm
I was looking at something else the other day and found the sticker with the manufacture info on the dash HVAC unit. "Specific Climate Systems" is the name. Google lead me to Victory Climate website and it appears they are still in business and have great parts catalogs with everything in them.
Page 2 Model HC212 is listed as Foretravel 1994-1999.
The sticker on my system says HC212 on it.
Link to RV parts catalog: Victory Climate Systems- Climate Control Products for a World in Motion (http://www.victoryclimatesystems.com/hvac-systems-recreational-vehicles-catalog.php)
Title: Re: Need Help With Dash A/C Problem .....
Post by: JohnFitz on July 05, 2014, 08:45:48 pm
That's a great find Krush! I see many familiar looking parts. It shows a unit for "Foretravel 1990-1992" but it doesn't match mine. Maybe it fits U225/U240 units?
Here's another resource with a good list of parts - scroll down to bottom to some handy .PDFs: Motorhome Dash AC and Heat systems (http://soldbyrichard.com/rvacheaterparts.php) Note: I've never done business with them. I think my '91 uses the "ACME Bubble Unit" Seltec is the brand of A/C compressor on my coach. There's a PDF on Seltec compressors with a good visual guide to all the variations to help you find the right one.
Title: 1991 U225 airbox
Post by: jdavid on July 10, 2014, 09:25:41 am
Does anyone know how to get at the airbox to remove it for refurbishing? Doors don't move or seal or close. Burnt out vacuum pump already and can't find a new one of those either.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Gary Bouland (RIP) on July 10, 2014, 09:51:30 am
JDavid, You can use any vacuum pump as all it does is provide vacuum to move doors in plenum from heat to AC and to fresh air. Search forum for fixes that others have used. Gary B
Title: Re: Need Help With Dash A/C Problem .....
Post by: JohnFitz on July 12, 2014, 12:34:19 pm
I can't be sure about a U225, but in general the air box (air distribution box) is mounted to the inside of the firewall. Under the glove box you'll find panels made out of plywood that you need to remove. They will have carpet stapled to them that you need to pull back in the corners and anywhere else there might be attachment screws.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Dave Katsuki on July 14, 2014, 12:15:39 am
Here's link to my old post on replacing the heater core, which shows what to do to get at the whole heater box with AC evaporator (on 99 U270, which should be similar to yours).
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on July 29, 2014, 08:45:50 pm
Can somebody with a coach in the 96-2000 range look at their reciever/drier and tell me if yours has the pressure switch mounted on it?
Mine has the switch mounted on the reciever drier (driver side, behind wheel, under access cover). But, mine also has a hi and a low pressure switch mounted on their respective hoses right at the compressor---but only the HI pressure cutout switch is wired up.
I blew the high pressure hose going from compressor to condensor and I'm going to replace the drier, expansion valve, pressure switches, and thermostat switch while I'm at it.
Title: Re: Need Help With Dash A/C Problem .....
Post by: rsihnhold on July 30, 2014, 10:03:11 am
I believe this is mine on a 98 and I don't see a pressure switch.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Chad and Judy on July 30, 2014, 12:44:23 pm
Mine looks very similar to the picture above, and I see no evidence of a pressure-switch.
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on July 30, 2014, 02:38:17 pm
Thanks for the picture and information, both of ya'll. Mine has the drier #054-00019 on the PDF below or in this picture the follows. The wire running to the switch on the drier (it's both a hi-pres cuttout and low-pres cuttout) is connected into the wires at the compressor switches.
So it looks like somebody did some modifications....which is why the unit ran even with low freon charge! The low pressure switch on the drier is pretty worthless unless all the refrigerant goes bye-bye. I'm going to reconnect the low side pressure switch.
http://comfortairgr.com/wp-content/uploads/2013/03/vcs054-00019.jpg (http://comfortairgr.com/wp-content/uploads/2013/03/vcs054-00019.jpg) (https://www.foreforums.com/imagecache.php?image=http%3A%2F%2Fcomfortairgr.com%2Fwp-content%2Fuploads%2F2013%2F03%2Fvcs054-00019.jpg&hash=f25f9d5f334c13b18c9bb95e5070b9a0" rel="cached" data-hash="f25f9d5f334c13b18c9bb95e5070b9a0" data-warn="External image, click here to view original" data-url="http://comfortairgr.com/wp-content/uploads/2013/03/vcs054-00019.jpg)
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on July 31, 2014, 08:08:31 pm
Some more tidbits of info. I couldn't find a legit model number on my A/C compressor, nor was there a manufacturer name. I need to look up the type and amount of oil recomended. When my line blew, I lost a fair amount of oil, and I am replacing the drier and TXV and blowing out lines.
The link above leads to this page on compressors and visual identification shows I have a QP16-1195 http://www.victoryclimatesystems.com/pdfs/rv/compressors.pdf (http://www.victoryclimatesystems.com/pdfs/rv/compressors.pdf)
Google leads to the manufacture website which has all the models listed and a PDF with a drawing/dimensions/basic design criteria including oil type (PAG 46) and volume required. TCCI Manufacturing and Que Products - United in Quality (http://www.tccimfg.com/QP-16.php)
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on September 01, 2014, 10:31:35 pm
Update on my dash A/C. I had it working, but I still felt it wasn't working as well as it should. The pressures were a little off and it would still cycle even on high (the thermostat switch that sensors air right after the evaporator was controlling the cycling).
A few weeks ago I blew the high pressure A/C line going from the compressor to the condenser. The hose failed right near the turbo. An 8 inch section of hose was very stiff and brittle from the turbo heat! I replaced the hose, put a heat sleeve over both of them, and made a redneck homemade turbo blanket from a turbo blanket kit. I'm going to wrap the exhaust manifold and the downpipe, but it was just too dang hot out. Keeping the radiant heat from the turbo away from everything in the engine compartment will be good enough for now.
I pulled the busted hose and took it to a hose expert--that's all he does is make any type of pipe/hose you can imagine. $55 for the new hose (most of the cost was the 12 feet of hose). A/C hose is unique, but it just uses barb fittings on the end.
Anyway, since I had the system open and exposed to air so long, I figured I may as well replace the reciever/drier and while I'm in there, replace the TXV (what's another $40?) and replace the thermostat (just in case it's faulty). Also, I wanted to pull the TXV out to ensure it wasn't clogged, as this will cause lower temperatures and some of the pressure indications I was seeing.
Somebody on my coach modified the wiring and put a combination high/low pressure switch on the receiver drier and disconnected the lower pressure switch on the low side. I will eventually hook the low pressure switch back up, but it's not as important as the high pressure switch for protection.
Anyway, attached are the pictures. It took me a while to find the thermostat switch--I ended up following the wire from the switch on the dash. It was in a spot that I just couldn't see it when I was looking around. I was able to reach everything without removing the doghouse, but I also used to stand on my head and work on boats. Lots of it was done by feel. All new orings were used.
When I pulled the TXV apart, my suspicions were confirmed: a blockage of desicant balls (about 6-10). I blew out the line backwards with dry air, but I wanted to make sure none were stuck in oil. My dad caught about 5 when I did my first air blow. I then flushed the line with Acetone (A/C flushing fluid will draw debates from all over the internet...acetone evaporates fast and leave little residue). To fully flush all the liquid out required me holding my finger over the discharge of the line and allow air pressure to build up and then releasing it.
Blew all the other lines out. Purged with nitrogen, hooked everything up and hooked up the filter/drier last (leave caps on it until ready to install), sucked in ~8oz of oil, and then purged system with nitrogen again, pulled a vacuum for a few hours, purged with gas, pulled vacuum, purged, pulled vacuum for 6 hours and filled up system with 5.5lbs (it seemed to be what made the pressures work the best).
Results?!!? On a super hot humid day, using outside air, the discharge temp at the vent was 60deg and the A/C didn't cycle. When I went to inside air and the sun went down, it would cycle on low fan, and as the inside cooled off, cycle very slowly on high fan (45-60seconds on, 1-2 min off). Discharge temp on high was in mid 50's +/- (I think). The thermostat is probably set around 47F.
So, that's that. The problem with A/C systems is not that they are complicated, it's just that the details matter. All this work took me quite a few hours to do correctly. Hopefully I don't have a leak and it doesn't work when I go to take my trip this week! haha
NOTE: TXV is on right side of air handler below two duct lines. Thermostat is on front of air handler forward/below the 8 ducts going toward the front of the RV.
Parts ordered from places above in thread.
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on September 01, 2014, 10:38:32 pm
Heat sleeve: I used this because I had the system open and could take both lines off the compressor
The turbo now has this on it: Amazon.com: Thermotec 15002 Turbo Wrap Turbo Accessories: Automotive (http://www.amazon.com/gp/product/B000C18QEO/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1)
And this is going to go around the manifold eventually: Amazon.com: Thermo-Tec 14004 Header Manifold Blanket for 4 Cylinder and Straight (http://www.amazon.com/gp/product/B000GVDBPO/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1)
Title: Re: Need Help With Dash A/C Problem .....
Post by: Kemahjohn on September 02, 2014, 09:07:40 am
You have done well-- after $3000 spent at Foretravel, my dash air still doesn't work properly. I'm about to tear into removing the evaporator to change out the fan. That is the issue now, not moving enough air. Due to having to dismantle the dash to access it, they quoted 10 hours labor, so I pulled the plug-- have to do it myself. I had the same issue, dissacant bag in the dryer failed stopped up everything. Expansion valve replaced, condenser fan replaced, compressor replaced, receiver / dryer changed, system flushed 3 times and vacuumed, then charged. The evaporator temp is still to high, so back to the drawing board. No fault of Foretravel, just a lot wrong with the system!
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 02, 2014, 11:19:58 am
I replaced evaporator, evaporator blower, expansion valve, compressor, dryer, and even the hoses before I was able to get my 1996 to blow as cold as I wanted it. Determining subcooling and superheat and adjusting the freon accordingly, I was finally able to freeze my knees. When Foretravel services freon, as soon as the evaporator outlet reaches anywhere close to 20 degrees below ambient, they stop adding freon. Consequently, they never achieve maximum cooling.
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on September 02, 2014, 11:52:13 am
The amount of charge is not that critical in this system because it has a TXV. If the TXV (thermal expansion valve) is working correctly, it will maintain a pre-designed superheat. Sub-cool would be the only way to really determine a proper charge.
The conceptual goal is to have enough refrigerant to have a solid flow of liquid to the TXV and also have enough charge to return some cool gas back to the compressor for cooling (refrigerant cools the compressor).
Newer vehicles have variable displacement compressors--and this requires pretty much charging just by weight.
Fixed orfice are pretty easy: charge till the return line to the compressor is cool (monitor pressures). Just take note of conditions to prevent over/undercharge.
In the end, it's part science, part art/gut.
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 02, 2014, 02:19:56 pm
I agree you don't need to worry about superheat with a good TXV, but when we couldn't get the air cool enough we started measuring line temperatures. We found that at idle everything was fie, but at 1500 there was a greater than 10 degree difference between front and back. We changed the lines and corrected the temperature drop and found our TXV was not operating perfectly. Installed new TXV and now we can get outlet temps in the 40's at highway speeds. I love it. The boss covers up with a blanket.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Kemahjohn on September 02, 2014, 04:23:07 pm
This is really good info, I have exactly the same issue, blows pretty cold at idle, but warms as rpm increases. I have changed the heater valve as well, it was through leaking hot coolant and bucking the AC. Still not as it should be.
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on September 02, 2014, 08:58:02 pm
Check to make sure you don't have massive air leaks in the front of the coach.
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 02, 2014, 11:43:37 pm
What are your high and low pressures?
Title: Re: Need Help With Dash A/C Problem .....
Post by: Kemahjohn on September 03, 2014, 09:39:53 am
We have found no air leaks, and we have looked. I'm going to check the pressures today. I haven't done that since Foretravel charged the system. I suspect that you are correct and that the system is under charged. I'll post what I find later this morning. I really appreciate the advice here--- my "from Canada" wife won't go far in the coach with no dash AC. Right now it won't keep you knee cap cool. Really disappointing after spending so much to get it going.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Barry & Cindy on September 03, 2014, 10:58:28 am
That's what the generator is for, to be used if dash air is not doing the job. Many do it every day.
Run gen, run both roof air to cool coach and load generator, use table fan on floor to blow on pilot and co-pilot. Generator is happy it is being used and humans are happy to have cool kneecaps.
Title: Re: Need Help With Dash A/C Problem .....
Post by: rsihnhold on September 03, 2014, 11:02:44 am
Agree with everything Krush said. I've had to replace everything that he did (except for the broken line) to get my AC up and running again, including having the drier pellets in the line.
On mine, the plastic fan cover that sits right up against the interior front of the RV was broken in a couple of spots. I was able to mostly fix it with some sheet metal and aluminized HVAC tape. The plastic shards from the broken cover were stopping the louvers from fulling opening and had also clogged up the fan a bit, resulting in low air flow. Once the broken plastic was removed my blower fan was able to move a lot of air. This will require removal of the doghouse to access all of this which isn't too bad once you realize where the screws are.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Kemahjohn on September 03, 2014, 12:12:41 pm
Well, I just got done checking the pressures--- ambient temp 86 degrees. Foretravel had charged the system and the pressures I read at idle (700 rpm) are 20 psi suction side and 110 psi high side. With my limited AC knowledge, this seems low for 86 degree ambient. I Increased the charge to 45 psi low side and 130 psi high side ( at this ambient I believe the low side should be between 45 and 55 psi, advise if I'm wrong). Evaporator air temp was not improved much, running 78 degrees. With inside coach temp of 83.
I believe that my fan has the same issue, it doesn't sound right and is not moving much air--- the sound would make me think of an open blower blade. Did you have to remove AC lines to remove the evaporator?
Title: Re: Need Help With Dash A/C Problem .....
Post by: rsihnhold on September 03, 2014, 01:01:41 pm
Well, I just got done checking the pressures--- ambient temp 86 degrees. Foretravel had charged the system and the pressures I read at idle (700 rpm) are 20 psi suction side and 110 psi high side. With my limited AC knowledge, this seems low for 86 degree ambient. I Increased the charge to 45 psi low side and 130 psi high side ( at this ambient I believe the low side should be between 45 and 55 psi, advise if I'm wrong). Evaporator air temp was not improved much, running 78 degrees. With inside coach temp of 83.
I believe that my fan has the same issue, it doesn't sound right and is not moving much air--- the sound would make me think of an open blower blade. Did you have to remove AC lines to remove the evaporator?
Your pressures aren't in the right range according to the R134 charge that came with my set of gauges.
I did not remove the evaporator. With the center dash doghouse removed, I was able to reach back and remove the broken plastic from the fan area. A couple of flashlights strategically placed allowed me to see that all of the damage was on the passenger side with no damage on drivers side. I didn't have to remove any hoses and was able to cut some sheet metal that I tek screwed and taped to MOSTLY seal the cover up. It isn't perfect at this point but I had no intention of taking everything out of there (now thats a big job). When the fan is working correctly, it moves quite a bit of air.
You might also look at replacing the Bosch relay that is right behind the accelerator pedal in the dash. You can get a 5 pack of relays pretty cheap off Amazon. I know mine had quite a lot of corrosion in the engine compartment.
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 03, 2014, 01:05:19 pm
Push the cruise control switch to RES twice. That should take the engine to high idle. Recheck pressures. Where is your coach? I would come by, but I am on the way to doctor. I would like to read the temperatures of the lines coming out of the condensor and the evaporator.
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 03, 2014, 01:09:16 pm
I had the problem of the broken fan cover. I had a new one mad out of fiberglass. If broken bad enough the valve can't close off outside air.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Kemahjohn on September 03, 2014, 01:27:28 pm
The coach is in Kemah. I can measure the line temps and report. I did check the temps at the compressor-- by putting my hand on them. The suction line is cool to the touch, and the liquid line is warm, approaching hot. I am suspecting that the low air flow might be the biggest issue, but not sure yet. Foretravel says the doghouse must be removed, all the wiring disconnected and the refrigerant lines removed th change the evaporator fan, thus the 10 hour estimate from them.
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 03, 2014, 02:49:22 pm
If the evaporator outlet isn't cold, increasing thr air flow will not help much. Your pressures are similar to what mine were when mine wasn't cooling. I ended up going through 3 TXV's till I found one that operated properly. My evaporator outlet line temps were running about 58. When everything was working it dropped to 29.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Kemahjohn on September 03, 2014, 03:57:37 pm
This may be an adjustable expansion valve, not sure. About what should my pressures be when working, 45-55 low side and 225-250 high side?
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 03, 2014, 05:19:41 pm
Yours shouldn't be adjustable. Yours is the same year as my older coach. It is both temperature and pressure compensated. The low side is controlled by the TXV and the high side is a function of the amount of freon. I am thinking your low side is a little high, but that is a guess. I was going to offer to come by and help (I am in Pearland), but I was just scheduled for knee replacement surgery.
Do you know the evaporator and condensor outlet temps at these pressures? At those pressures your liquid line coming out of condensor should be about 125 degrees.
Title: Re: Need Help With Dash A/C Problem .....
Post by: krush on September 03, 2014, 07:47:37 pm
29 is too cold on evap outlet temp...it's going to freeze up. Expect to see around 175-225psi on the high side and around 20-50 on the low side. Obviously give or take a bit, dependent on many variables...haha
You're aiming for about a 20degree AIR temp drop across the evap.
Line coming back to the compressor AT the compressor should be cool and sweating (if humid out). Hi side line will be hot leaving.
Low air flow over the evaporator will cause COLDER temperatures, cycling of the thermostat (if system has one) and reduced flow/lower pressures as TXV closes. Also, make sure the sensing bulb of the TXV is getting good contact and wrapped with insulation around the discharge line.
Title: Re: Need Help With Dash A/C Problem .....
Post by: sedelange on September 03, 2014, 08:25:12 pm
I agree 29 is a little low but that was with a cabin temp of about 70 and it was much better than I was getting with the other two valves which were closer to 55. Even with 29 the freeze detecting switch with the sensor between the evaporator and heater coil never shut off the compressor.
Title: Re: Need Help With Dash A/C Problem .....
Post by: Kemahjohn on September 03, 2014, 08:42:55 pm
I went back over to the coach and tried again--- more confusion. With the engine at high idle, suction pressure is now at 15psi and high side is 150psi. Evaporator air temp s 74 degrees, cabin temp 84 degrees. I forgot to take my infrared thermometer with me, so I'll get the line temps in a day or so I'm going to have to give up on it for a few days, taking the coach up to Midland Odessa to visit my daughter. Best wishes on the knee replacement, they can be tough. On the other Hand, a few years ago my Mom's 92 year old husband had both knees replaced at the same time, and went deer hunting 4 weeks later! I'll keep you posted as I fumble through this thing.
Title: Re: Need Help With Dash A/C Problem .....
Post by: TulsaTrent on September 06, 2014, 02:50:28 am
Today, I was looking at the alternator installation and happened to look at the A/C compressor. My dash air had not been working, but I finally discovered why. Please see attached photo. I do not know when the fan belt disappeared, but small parts of it are splattered along its flight path on the insulation pad on top and both sides. It looks like it must have disintegrated. I cannot find any evidence of further damage from the flying belt.
Trent
Title: Re: Need Help With Dash A/C Problem .....
Post by: Raymond Jordan on September 06, 2014, 02:15:28 pm
Hi Trent, If it is just the belt, you got off easy. Now if the compressor is the cause of the missing belt, it gets a little harder. Raymond
Title: Re: Need Help With Dash A/C Problem .....
Post by: TulsaTrent on September 06, 2014, 03:05:06 pm
I have my fingers crossed although something caused that belt to disintegrate.
In my crude attempt at troubleshooting, I discovered that the pulley on the compressor turned freely. I tried to turn the other pulley to which the belt is attached, and the Cummins monster just laughed at me. :)
Trent
Title: Re: Need Help With Dash A/C Problem .....
Post by: D.J. Osborn on September 06, 2014, 07:18:35 pm
In my crude attempt at troubleshooting, I discovered that the pulley on the compressor turned freely.
Turning the pulley on the compressor will tell you only whether or not that bearing is bad, unless the compressor clutch is engaged. The clutch is electromagnetic and will engage the compressor only if there is sufficient refrigerant and the air conditioner is calling for cooling. If the compressor is seized then the belt will likely be destroyed when the clutch is engaged.
Title: Re: Need Help With Dash A/C Problem .....
Post by: TulsaTrent on September 06, 2014, 11:26:12 pm
Turning the pulley on the compressor will tell you only whether or not that bearing is bad
David,
I think you just told me that since my pulley turns freely (and everything is off), my bearings are not bad. That's a good thing, right?
Does anyone who is willing to share know what that length of that belt is? It appears to be a simple V-groove belt. I inherited a couple of belts and can attempt to install one of them, but I would rather know which one is the right one first.
I do not have much experience replacing belts, but I do recall someone mentioning recently that it was easier to install it on the smallest pulley last. Thank you, whoever you are, for sharing that tip.
Trent
Title: Re: Need Help With Dash A/C Problem .....
Post by: OldManSax on September 07, 2014, 08:12:35 am
I think you just told me that since my pulley turns freely (and everything is off), my bearings are not bad. That's a good thing, right? Trent
Trent, Right...... to a certain extent. That particular bearing allows the belt to rotate with the AC system off & the engine running; winter operation, for example.
When you rotated the pulley on the compressor, with everything off, the pulley should rotate freely (as you said it did) and the center of that pulley (attached to the actual shaft of the compressor) should be stationary. That is the first test.
Next, WITH EVERYTHING OFF, try to rotate the CENTER of that same pulley. You will need a strong hand and may not be able to move it anyway. If you can move it, it will turn like a small engine. It has compression. If you can't turn it, try the next step.
DO NOT START ENGINE! Have a helper turn the ignition key to "ON" then turn on the dash AC while you are looking at the AC compressor. MAKE SURE THE HELPER UNDERSTANDS NOT TO START ENGINE!!!!! You should hear a "CLICK" as the electromagnetic clutch engages. Now the pulley and the center should be engaged as one unit and you should be able to rotate the entire unit with you hand. It should turn, not make any noise, other than perhaps a slight hissing internally, and have some resistance as the compressor tries to compress the refrigerant. If you cannot turn it at all, the compressor is locked up and needs replacing.
TOM
Title: Re: Need Help With Dash A/C Problem .....
Post by: Barry Beam on September 07, 2014, 08:18:00 am
Does anyone who is willing to share know what that length of that belt is? It appears to be a simple V-groove belt. I inherited a couple of belts and can attempt to install one of them, but I would rather know which one is the right one first.
I think you just told me that since my pulley turns freely (and everything is off), my bearings are not bad. That's a good thing, right?
The bearings on the compressor clutch appear to be good, but there is much more to the story. The information others have provided here is right on target.
Title: Re: Need Help With Dash A/C Problem .....
Post by: TulsaTrent on September 07, 2014, 10:13:57 pm
Anyone messing with belts should have a tension gauge. You can get them At NAPA or on line. You can't properly tension a ribbed belt without one.
Once you have the tension gauge (https://www.amazon.com/Gates-91107-Belt-Tension-Tester/dp/B000MUTAGS). How do you know how much to set the tension. No number is indicated on the Gates 9476 Manufacturer wrap/paper. Thank you, AL
Title: Re: Need Help With Dash A/C Problem .....
Post by: John44 on August 26, 2017, 12:18:47 pm
As far as I know the automatic belt tensioners have 2 marks and a pointer and while running the pointer should be between the 2 marks,what is there to adjust?When the spring or the bearing wears out you replace and save the old one in case the new one falls apart you'll have a spare.
Title: Re: Need Help With Dash A/C Problem .....
Post by: wolfe10 on August 26, 2017, 12:36:09 pm
If we are talking about the automatic belt tensioners, they can fail in three ways:
1. Bearings can fail 2. Tensioner spring can fail or weaken allowing belt slippage 3. The dampening function can fail. This is one of the more common failures and identifiable by the bouncing of the belt. VERY hard on the bearings of all accessories it drives.
Here is a short video on #3 by Gates Corp: http://www.youtube.com/watch?v=uTLV5IU_IMM
Title: Re: Need Help With Dash A/C Problem .....
Post by: propman on August 26, 2017, 01:22:47 pm
There is no auto belt tensioner for the Air Conditioner Compressor Belt (Gates 9476 for ISL 400) Mine just broke off. I will perform Reply #53 OldMenSax steps in an hour. Going to get the belt. I think when we replaced the water pump, we did not reinstall the Air Conditioner Compressor belt with correct tension, it had looked a bit lose. However the AC Compressor was replaced about year ago so i am hoping there is no issues there.
Title: Re: Need Help With Dash A/C Problem .....
Post by: wolfe10 on August 26, 2017, 01:28:07 pm
There is no auto belt tensioner for the Air Conditioner Compressor Belt (Gates 9476 for ISL 400).
Correct, on the Cummins C and L, the A/C compressor is "manually" adjusted by rotating the compressor. All other accessories are on the serpentine belt/automatic tensioner.
Title: Re: Need Help With Dash A/C Problem .....
Post by: propman on August 26, 2017, 05:50:43 pm
Trent, Right...... to a certain extent. That particular bearing allows the belt to rotate with the AC system off & the engine running; winter operation, for example.
When you rotated the pulley on the compressor, with everything off, the pulley should rotate freely (as you said it did) and the center of that pulley (attached to the actual shaft of the compressor) should be stationary. That is the first test.
Next, WITH EVERYTHING OFF, try to rotate the CENTER of that same pulley. You will need a strong hand and may not be able to move it anyway. If you can move it, it will turn like a small engine. It has compression. If you can't turn it, try the next step.
DO NOT START ENGINE! Have a helper turn the ignition key to "ON" then turn on the dash AC while you are looking at the AC compressor. MAKE SURE THE HELPER UNDERSTANDS NOT TO START ENGINE!!!!! You should hear a "CLICK" as the electromagnetic clutch engages. Now the pulley and the center should be engaged as one unit and you should be able to rotate the entire unit with you hand. It should turn, not make any noise, other than perhaps a slight hissing internally, and have some resistance as the compressor tries to compress the refrigerant. If you cannot turn it at all, the compressor is locked up and needs replacing.
TOM
Well I did all that. In the attached images where we see the white front with a dark grey triangle section (I think is the center part is freely moving by hand when everything is in off position. When i followed the above steps that center part kept moving freely by hand however before or after I could never turn the part (pulley?) where the belt rides on at all. The compressor is few months shy of two years old. Do i have a bad compressor? I am afraid if i install the new belt, it is also going to brake. (https://www.foreforums.com/imagecache.php?image=http%3A%2F%2FTXWLDELL44%5CSCH-I545%5CCard%5CDCIM%5CCamera&hash=7a2a5dc690e1506cb47a2ca04d1a388b" rel="cached" data-hash="7a2a5dc690e1506cb47a2ca04d1a388b" data-warn="External image, click here to view original" data-url="http://TXWLDELL44\SCH-I545\Card\DCIM\Camera)
Title: Re: Need Help With Dash A/C Problem .....
Post by: red tractor on August 26, 2017, 07:47:17 pm
Sounds like a bad bearing on the pulley do not know if the compressor is bad.
Title: Re: Need Help With Dash A/C Problem .....
Post by: OldManSax on August 28, 2017, 09:11:14 am
Well I did all that. In the attached images where we see the white front with a dark grey triangle section (I think is the center part is freely moving by hand when everything is in off position. When i followed the above steps that center part kept moving freely by hand however before or after I could never turn the part (pulley?) where the belt rides on at all. The compressor is few months shy of two years old. Do i have a bad compressor? I am afraid if i install the new belt, it is also going to brake. (https://www.foreforums.com/imagecache.php?image=http%3A%2F%2FTXWLDELL44%5CSCH-I545%5CCard%5CDCIM%5CCamera&hash=7a2a5dc690e1506cb47a2ca04d1a388b" rel="cached" data-hash="7a2a5dc690e1506cb47a2ca04d1a388b" data-warn="External image, click here to view original" data-url="http://TXWLDELL44\SCH-I545\Card\DCIM\Camera)
What Ron said. I think the bearing is bad also. That area should not be white. Normally that indicates severe overheating, usually caused by failed(ing) bearing or compressor. The clutch assembly can be replaced but be careful not to damage the shaft seal. Damage will cause eventual loss of refrigerant. When you turn the inner (white) part, does it turn smoothly? Like a small engine would turn? It should be smooth with some compression felt as it is BEING TURNED IN THE CORRECT DIRECTION. It will (should) have hard compression if turned in the wrong direction.
TOM
TOM
Title: Re: Need Help With Dash A/C Problem .....
Post by: stump on August 28, 2017, 09:49:45 am
On the pulley where the belt goes does it spin freely? If not Bearing is bad. New compressor clutch will be needed. Can you turn the triangle part multiple revolutions? If not compressor is locked up. Make sure it will turn at least 3 or 4 full revolutions. They can throw a rod an turn about 7/8th around and then lock up. If everything spins put a belt on it and see what happens. If you do need a compressor clutch it's almost cheaper to buy the whole compressor. I just replaced mine on my 91 New Sanden Compressor was about 185.00 T/X valve about 25.00 and Filter dryer about 15.00 We have a Campbell Brown here in Charlotte,Nc is where I buy my A/C parts from also Hoses etc.
Title: Re: Need Help With Dash A/C Problem .....
Post by: propman on August 28, 2017, 10:49:54 am
@ OldManSax (Reply#68) "When you turn the inner (white) part, does it turn smoothly?" Yes and without much force at all. "It will (should) have hard compression if turned in the wrong direction" it turns to both directions the same way, maybe a slight resistance when turned the opposite direction. @ stump (Reply #69)"On the pulley where the belt goes does it spin freely?" No it does not at all. I tried by hand only, but really tried. "Can you turn the triangle part multiple revolutions?" Yes, with just 3 fingers, no problem. Two years ago, immediately after we purchased it I had Industrial Power in Fort Worth, TX do some work. At that time for $1192 they "Installed new AC Compressor and Receiver Drier and low pressure switch, Evacuated and charged AC system with R-134A" It worked fine for 2 years. But relative to amount of time we use and run the AC its life span was very very short. Stump when you were able to replace the Compressor on your own how does it work, when unbolted, I assume Refrigerant will escape, unless it is professionally Evacuated. I believe I can figure out a way to Evacuate and capture R-134A. So I have a way of doing that, is it just unbolt/remove and install a new one? If it is as easy as it sounds I sure would like to not pay so much for it again. Thank you, AL
Title: Re: Need Help With Dash A/C Problem .....
Post by: stump on August 28, 2017, 12:43:01 pm
Al If the belt pulley will not turn the bearing is bad. I have all the tools and equipment to do A/C service work. I was hvac contractor before I started Trucking. I have the old clutch still on my compressor that went bad on my peterbilt and I have the one on the R-12 compressor that was on my Foretravel. I can Pull one off if you think it would work on yours. You can borrow the clutch hub puller tools from Autozone, Advance Auto,Etc for free just leave a deposit on your CC. Plenty of videos on Youtube to show you how.
Title: Re: Need Help With Dash A/C Problem .....
Post by: propman on August 28, 2017, 02:47:53 pm
Al If the belt pulley will not turn the bearing is bad. I have all the tools and equipment to do A/C service work. I was hvac contractor before I started Trucking. I have the old clutch still on my compressor that went bad on my peterbilt and I have the one on the R-12 compressor that was on my Foretravel. I can Pull one off if you think it would work on yours. You can borrow the clutch hub puller tools from Autozone, Advance Auto,Etc for free just leave a deposit on your CC. Plenty of videos on Youtube to show you how.
I found some videos and actually got excited. If i am lucky looks like I don't have to mess with compressor lines. Just from the front remove the clutch and the pulley and replace what needs to be replaced to fix the clutch and or the pulley bearing?
I wonder our FT AC Compressor is GM like. GM type requires some specific tools but other than that don't look too difficult. https://www.youtube.com/watch?v=URqFd3KkSRY
Title: Re: Need Help With Dash A/C Problem .....
Post by: OldManSax on August 28, 2017, 02:50:06 pm
What Stump said. Pulley should spin freely by hand with little or no noise.
TOM
Title: Re: Need Help With Dash A/C Problem .....
Post by: stump on August 28, 2017, 03:38:45 pm
This Video is applicable to your compressor https://www.youtube.com/watch?v=NuX3Pwde6-g
Title: Re: Need Help With Dash A/C Problem .....
Post by: joeszeidel on August 28, 2017, 05:15:53 pm
I am not much help with a lots pf help chiming in. I will say this, listen to Stump. Dont ask me how I know. The great thing about this forum is like what Trent said this is better than a Foretravel Encylopedia.