Dash AC wasn't cooling well when we went to top the fuel and propane tanks last weekend. Have not needed it since last summers vacation. Thanksgiving vacation was cool enough it seemed to work well.
Thought it was just low on Freon so I hooked up the gauges and set the high idle with evap fan on high.
Compressor runs continuously, condenser fans only cycled a couple of times when high side hit about 225 psi.
I'm no AC expert so I thought I would put this out for suggestions. Here are the gauge readings.
Your low side is running very low pressures. In the second photo it's in a vacuum. Somebody more knowledgable than me will hopefully respond but it looks low on refringerant to me. Is your condensor fan not running continuously? That doesn't seem right.
I'm am sure that DSD will respond soon enough and let you know about those gauges and their readings.
I believe the condenser fan should run as soon as the AC is turned on so you should find out why
it isn't running continually.
The first thing I'd do with your low side reading is add a can and see what happens.
I added a couple of pounds, only thing changed was the High side went up. 🤷♂️
Get your fan working continually the Freon needs to be cooled. If it isn't cooled the evaporator
can't cool properly.
The condenser fan motor on mine was cycling also. It was the resettable breaker going off and on. Replaced the fan motor and it has worked ever since.
You might have a restriction in the system. Usually if the low side is in a vacuum the expansion valve is clogged but you normally won't have very high on the high side either.
Update:
I was able to get the AC working this afternoon, I had concluded that the expansion valve was stuck or just failed entirely. With 225 psi on the high side and zero or even a vacuum on the low side, a restriction in the system seemed logical. The most likely place being the expansion valve. I had intended on ordering a new one and a dryer today but NAPA was closed. (Memorial Day) so when I returned from work I thought I would try hooking up the gauges again. No change, low side almost zero and high side around 225 psi.
There is a "Hail Mary Method" we use at work that sometimes results in success. So I took my rubber handle phillip head screw driver and gave the expansion valve several "whacks" and I be danged......the low pressure rose! so..... I gave it a few more aggressive "whacks" and pressures returned to what I thought they should be. ( 30 to 35psi) the condenser fans started running when the high pressure reached around 240 and the condenser temp reached whatever temp the trinary switch cycles at.
FYI.... the condenser fans on ours are controlled by a Trinary switch.
Definition: A/C Trinary switches combine low and high-pressure compressor clutch cut-off functions plus an electric fan engagement signal at 254 psi. The low-pressure cut-off of these trinary switches is 30 psi and the high-pressure cut-off is 406 psi. Perfect usage when running electric fans.
I may still need to change the TX expansion valve, I replaced it and the dryer just a few years ago, but for now its working and I think I'll leave well enough alone. Plans are to try it a couple more times before our summer vacation, if no issues, we hit the road.
I want to thank everyone for their replies and suggestions, nice to know that there is always members willing to help.
Great forum to be a member of. ^.^d
You nailed it Red Tractor
Last year I had someone put refrigerant in my dash AC system. It ran for a while well but I noticed when I tried it recently I wasn't getting any cold air again. Last year I bought the required equipment to put freon in or vacuum the system out but don't really know much about how to use it and haven't tried learning yet. I need to stop and get some refrigerant and try hooking the system up and seeing what happens..
Glad you got it figured out though. And thanks for posting it.
Justin, last couple of coaches I was involved with had massive corrosion in the receiver dryer. Im suspecting you have the same issues. I cant give you a logical explanation to the corrosion, the system in theory should be sealed and completely dry/sealed. Nevertheless I really recommend replacing the dryer. Once you have it removed Im betting if you cut it open as I have you will see the problem. At that point I have flushed out the pressure hose to the expansion valve and replaced it. Dont want to contaminate system any more if possible. Having a recovery system helps a ton.
Scott
Amazon.com: Universal Air Conditioner RD 8214C A/C Receiver Drier : Automotive (https://www.amazon.com/gp/product/B003R4TBDS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
Amazon.com: 1600 A/C Expansion Valve Peterbilt Truck AirSource NEW : Automotive (https://www.amazon.com/gp/product/B0055F5EUQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
If it gives me anymore problems .... I'll replace the TX valve and the dryer. I'll check my records to verify but I think I replaced them both in 2018.
How difficult is it to access the expansion valve? I assume the dash has to be mostly disassembled?
Foretravel recently worked on my dash air and my dryer was replaced by them and the system worked again. My dryer was only three years old. Hmmmm.
1. 0n some coaches one of the hose nuts can be the hardest part of the job due to how the expansion valve is installed.
2. Yes but once you get started it is just a bunch of those square headed screws. Take pics as you remove sections of the dash just in case you have a honey do come up.
Mike
If you have the system opened to atmosphere it is best practice to replace the dryer.
Mike
On our 95 U280, just remove the front grill, (4 latches) and its right there. Hardest part it removing the sticky insulating material on the valve and fittings.
On my 2001 it is under the wiper motor and forward of the evaporator. It was a pain to change. The sticky tar material prevents condensation on the cold valve. It must be reinstalled.
you're just bragging now...
:D
well.......the 95's are something to brag about! ^.^d
For those with a good ole' 95 GV with similar AC, these are parts that I have used.
Dash AC -
Evap blower NAPA # BK_6551744
Sanden compressor #4664
PAG100 oil
Napa #208317- filter /dryer
Napa #207376 - TX valve
Condenser fans -AV1110 (Amer. Volt)
And Justin.
You left out how many pounds of Freon. We recharged a few weeks back and put in 3
I noticed there were no bubbles in the sight glass so maybe we're good. I guess we'll know after a few hundred miles in this Arizona heat.
Well..... Bob, I left out how many pounds of freon because I don't know. ;D Maybe some AC guru on the forum here will know and chime in? I have a 30lb bottle and after vacuuming the system down, I fill with 134A until I get a good pressures on the high side based on the chart and hope the low side looks good and bubbles are mostly gone.
DISCLAIMER: I am no refrigeration expert...... I read, then try to remember what I've read long enough to put it in practice. :dance:
Easier to weight the bottle before and after to get a good idea or if you are anything like me3... pick it up before and then again after...then put it up and forget to weigh it at all.
The AC system on my Coach holds 80 oz or five pounds of 134a Freon I weigh it.
Freon Capacity of the A/C system ? (https://www.foreforums.com/index.php?topic=25268.0)
Filling dash AC system (https://www.foreforums.com/index.php?topic=43018.0)
Dash Air Conditioner Refrigerant and Oil Capacity (http://web.archive.org/web/20200111051919/http://beamalarm.com/Documents/dash_air_conditioner_refrigerant_and_oil_capacity.html)
Here you go
My dash a/c was functioning but not very well in this triple digit heat index.
I changed the drier and expansion valve and did some repairs to the lower section of the evaporator box on the firewall. The plastic bottom of the case holding the drain tube and the vacuum generator for the fresh air door had been broken from age and was not holding them in place. I was able to put them back on with some thick sticky insulating tape wrap and now it works just fine. Saved about $800 just for a new evap box! Cleaned the condenser and oiled the fans.
After vacuum and recharge, the end result is about 20 degrees cooler than ambient ( not 40 degrees like I like it!) out the vents and the recirculate function on the blend doors working as it should. I still need to change the compressor belts and maybe a new condenser in the future.
Jerry
I added 5 lb of refrigerant and while I'm not completely sure of the readings I was getting 40° blowing out of the duct with outside temperatures north of 80 I believe it was at the time.
I bought a new dryer and expansion valve, but haven't installed it yet.
Didn't know if the boondockers welcome host would appreciate me doing work on the coach in her yard but she was okay with putting refrigerant in. We'll see what time shows but I'm pretty sure I'm going to have to replace the dryer and maybe the expansion valve.
I did the work on June 30th so really only a month and a half has gone by and everything still blowing cold. I may have to put another pound of refrigerant in but maybe not.
What did the gauges look like while the system was running? Also a 40° drop is really good. That's what I used to target when I did A/C work. 30° drop was acceptable, but 40° was great.
I think the picture that I posted was with the engine running and the AC running. Right after I put the refrigerant in. I thought the readings were a little bit low for what I thought I should be but I was happy with the results so. I used all 5 lb of refrigerant didn't buy any more than that. I'm just going to top it off with a can every once in awhile until I can really rebuild the system properly.
The numbers from your picture would be with the compressor off. 100 high 100 low. It should be around 30-35 low and 200-250 high.
Jerry...source and part numbers please for the drier and expansion valve
thx
H
Sorry Hans, my goof.
Both parts I ordered online from NAPA.
The a/c expansion valve is part No. TEM 207376 for $29.10 https://www.napaonline.com/en/search?text=TEM%20207376&referer=v2
The a/c receiver filter drier - H/D truck is part No. TWD ME17159 for $40.99 https://www.napaonline.com/en/p/TWDMEI7159
I bought the insulating tape for $30 at O'reileys for a big roll and had plenty left over for other projects.
Jerry
I'm getting ready to charge my dash AC. It had the AC compressor replaced by the RV dealer where I bought the coach four years ago and the dash air worked OK but slowly lost it's charge over that time. I bought some UV dye and intend to inject that along with the new refrigerant in order to help locate the leak. This product recommends 1/4 oz. for a typical vehicle and has four doses in the bottle (1 oz. total). Given the length of the refrigerant lines it seems like I should use more? Maybe two doses? Anyone have any experience with this or at least an informed opinion?
thanks
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