The title pretty much says it all.
My '94 U-240 uses R-12 for the dash air. It is probably the last year to use R-12 instead of R-134. It is blowing warm air, for there is no freon in the dash air system. The AC tech is trying to come up with repair pricing and options, such as changing the sysyem over to R-134 or merely refilling with R-12. He can't find a leak in the low pressure side with air pressure, so to see if the leak is in the HP side (compressor) he'll have to pressure it up with freon. Problem is that if the compressor is bad he said he no longer has a recovery system for R-12 so we'd lose the R-12. He's trying to talk me into converting to R-134. In order to weigh the economics we need to know how much freon the system holds. Any ideas?
Thanks,
Glen
Don't let him rip you off for parts and service. 134 only requires different oil and you can buy the 134 with the oil already in it. I changed out my last GV and several cars to 134. NO PART CHANGES. All he needs to do is vacumn pump the system and fill with r134 since your r12 is already gone. He should have a machine that does it all in one whack.
3 lbs comes to mind but I don't really remember how many I used.
He can use nitrogen to pressurize the system to look for a high side pressure leak. It should hold about 3 1/2 lbs and yes convert it to 134a
I was more comfortable staying with R12 for a system designed for R12 and a compressor lubed with R12-friendly oil.
Sorry, don't know capacity. As I recall, they are not filled until the sight glass is clear.
MOT (Keith) did our evacuate and recharge.
Brett
I think that there is some requirement that your "technician" be able to recover R12 before he can legally inject it into your system. If there is a leak then it will escape to the atmosphere which is exactly why R12 was put on restriction.... and, since your system has no R12 in it, there is almost certainly a leak.
I'm looking at this same problem myself and leaning towards "investing" in some Harbor Freight devices (a vacuum pump, manifold (gages and valves) and R134a refrigerant) and just do it myself. Any other option (at this late stage) looks like it would be a lot more expensive.
I, too, would have some suspicions about your "tech". :)
Craig
Both of my 93's have been converted to 134 without a problem. Whether you do it yourself or have the tech do it, don't wast your money on more R-12. R-12 will not be available for very much longer, even as Freeze 12 so why use it when the changeover will be less cost. If the tech doesn't have to evacuate the system, the change to 134 should not be much more than the cost of the 134.
I have read that the newer ES 12A is even more economical and works great in the old compressors. you might want to check it out.
Going to charge mine with this stuff. Have not read any negatives yet. Can it be cheap and good? A couple of quotes:
"ENVIRO-SAFE R-134a REPLACEMENT w/ DYE is an OUTSTANDING refrigerant that is colder than Freon and fully compatible with both R-12 Freon and R-134a. 6 CANS are only $34.95 with FREE SHIPPING! ENVIRO-SAFE R-134a REPLACEMENT w/ DYE was developed to replace both R-12 and R-134a in any R-12 and R-134a application. EPA license is NOT REQUIRED to purchase or use. ENVIRO-SAFE R-134a REPLACEMENT w/ DYE is a "second generation" refrigerant that takes less to replace both R-12 and R-134a. Each 6 ounce can of ENVIRO-SAFE R-134a REPLACEMENT w/ DYE is equivalent to 18 ounces of R-12 and 16 ounces of R-134a. Being a hydrocarbon refrigerant, ENVIRO-SAFE does not have to be charged under vacuum which is very popular with Do-It-Your-Selfers. ENVIRO-SAFE technical info, installation procedure, 30lb & 50lb cylinders, top can taps and adapters are available at RefrigerantGuy.com. SIX PACK includes 6 - 6 oz. cans of ENVIRO-SAFE R-134a REPLACEMENT w/ DYE."
Above is from an ebay ad. $34.95 for 6 cans with free shipping.
And from a BMW forum:
"Anyway, I evacuated the system last night and shot two cans of ES12a into her...jeez that stuff gets cold! At highway speed, in 96° ambient outside temp, I am getting 38° at the center vent. My R12 cars don't achieve that. At idle the temp only creeps up to 40° or so."
Pierce
They seem to be saying that ES12A can be put into R12 systems as well as R134A systems and will perform better so it looks like it's a good idea. But not many people are doing it yet and buying it locally seems difficult (if not impossible). On one forum a person who claimed to be working for an HVAC outfit evacuated R12 from his Mustang, installed ES12A, found it to be working fine but is now going to go back to R12 but doesn't explain why (or at least not very well).
We'll know much better after you try it. :D
Craig
If you can find R-12 it will probably be more than you will want to pay. There are flushing agents that can be used to remove all the old oil and clean out the system. This is good time to install a rebuilt compressor or have the old one rebuilt. It should have the correct amount of R-134a compatible oil in the compressor. Also at this time a new filter-dryer should be installed. A vacuum can be pulled on the system and the vacuum should hold for a few hours if there are no leaks. The hoses on a cheap gage set may not be that great for holding a vacuum though. At this point you could also pressurize with a small amount of R134a and check for leaks (soap and/or a freon detector). Normal procedure if the quantity of R134a is not known is to add slowly with the compressor running until there are no bubbles in the sight glass. I'm guessing that you will need about 5 or 6 cans. R134a is about $10 a can at Walmart and up to $15 in automotive stores. Too much freon in the system reduces efficiency as the extra is stored in a liquid form in the condenser and effectively reduces the size of the condenser. Too much oil in the system also reduces the efficiency as it coats the inside of the condenser and evaporator and reduces heat transfer. An R12 system converted to R134a will not cool quite as well as it did with R12. It needs a slightly larger condenser and evaporator for equal cooling. I'm not a refrigeration guy, just stuff I picked up from reading and listening.
When ours was fixed, it took 5.5 pounds of 134 refrigerant.
This is propane, right? I've been tempted to try it. Lots of people are shocked when they consider using propane for refrigerant but consider what Freon does when it burns. Phosgene gas.
Did anyone read what was in Wikipedia about ES-12a. HC-12a - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/HC-12a) It's illegal to use it in place of R-12 in automotive systems, but it's not illegal to buy or sell it. It's a blend of Propane and Isobutane. Before freon was invented, some of the refrigerants in use were either flammable or poisonous with people dying from their use. The chemist that invented freon would inhale the stuff and then blow out a candle as a way to promote the product. Propane is a good refrigerant in regards to the cooling effect. Just be forewarned about the danger involved. As long as there are no leaks, or accidents to contend with you should be okay. BTW a refrigerant with a letter after the number indicates it is a blend of refrigerants.
Thanks for all the replies and advice.
I had been waiting on an answer to this question from Foretravel when I decided to post it on the forum also. Foretravel did reply to me that it takes about 72 ounces, or 4.5 pounds.
He, my mechanic, had tried pressuring the system with N2, but the leak was so small that he couldn't find it with N2. He said he'd have to put in a dye and then I'd just use the air conditioner, and the dye would eventually pinpoint the leak. I was afraid that I'd eventually have to again refill the system, and I didn't want to have to buy R-12 again. I decided to change to R-134 now and get it over with, even though it may not cool quite as well as the R-12. Like Kent said, it may not even be available next time.
For what it's worth I did want to take it MOT for the repair and at the same time have them troubleshoot a generator/house air conditioner problem, but Keith called me back and told me they were too booked up to get me in right now.
Glen
Well, I bought a case of 134a and am going to give it a go once it gets here. Hope the refrigeration cops do not read this. I like the fact that is does contain a dye for leak detection
My system was converted a long time ago before I bought it. The dash air does not blow cold but I can add a five or six cans and get a week or so of coldish air. I see at the auto parts store there are cans of oil next to the 134a. I didn't add any oil. Is there a way to tell if it needs the oil or is there a ratio of oil to refrigerant?
Need a bit of help. Does anyone know which port is the fill/low pressure port on my 94 GV?
On the 1993 U240: low side (center forward bulkhead); high side (driver side of forward bulkhead lower than low side).
Brett
JUst to clarify, the low or fill port is on the passenger side and is the larger diameter line
Yes.
Brett,
Thanks once again.... I.O.U. You have really helped me a bunch.
In the never-ending quest for more tools, I bought a Harbor Freight A/C manifold with gauges yesterday. This manifold comes stock with R134a quick-connectors so I put a pair of those over my R12 connectors and connected everything up. Pressures on both sides were about 95 (not sure what it was ... psi?) and paperwork with the manifold said that both sides should be "about the same".
I think looked around for some idea of what the pressure gauges should be measuring and came up with a blank.
So I still have R12 in the system... my question is what pressures should I be measuring?
Craig
Craig,
In my (limited) experience, the suction side should be lower when the compressor is running. It is the differential that makes for the expansion and thus the heat extraction. In cars that I have refilled (using a high and low side gages), when it was up to spec the low side was typically somewhere around 25 to maybe 40psi and the high side would be around 120psi. Also the site glass would have bubbles when a little low (obviously not when empty!) and as it would take freon, the bubbles would gradually disappear. Also, the suction side piping would get very cold and the high side would get very warm. This has been on R12 systems on various makes and models of cars. No idea if the coach would signifigantly differ from that, but I would guess they would be similar. I have changed over a few to R134, without chaging the recomended components and got away with it, but it depends on the receiver dryer state at the time of the changeover. The things you will do when you are a starving musician ;D ...
I am sure that others with actual knowledge will chime in, but it has worked for me... as to the specs, I just used an automotive encyclopedia to get some generic values for the pressures that I received while taking a Volkswagon apprenticeship course...
YMMV!
Don
Don... thanks for the info. I forgot to mention that the write-up that came along with the manifold said to check first with the engine off and the pressures should be "about the same". I did not try testing with the engine running and the A/C system working yet because that was the next step and I was supposed to determine "from the owner's manual" what the pressures should be before proceeding on.
So I guess tomorrow morning I'll run the engine and ask the DW (who is busy installing tile in the bathroom) to high-idle it for a while.
Golly, this is fun! :P
Craig
I went to fill mine with refrigerant thinking it was very low (my compressor did not turn on) well my gauge showed 50lbs on the low side and no bubbles in the site glass. So I am guessing I have an electrical issue. Checked the under dash fuse and it was fine. What next?
My U225 has a set of 12vdc circuit breakers next to the battery box in the basement. I seem to recall that there is one for air conditioners in there somewhere. I could be wrong but you might want to check.
Craig
I would say that is too low considering the compressor isn't going. It could very well be too low and the pressure switch that allows the compressor to turn on is just doing its job. Most systems have a connector which you can put a jumper on to engage the compressors clutch. When I haven't been able to locate that, I have successfully just provided 12v to the A/C clutch to spin the compressor and create suction to add the refrigerant... FWIW
Don
Going to look now and also see if I can pinpoint that on my wiring diagram
Now that I am back from our first long trip. I am back dealing with no dash air (we used the Genset and roof air when needed) and really need to try to get this working before I succomb to taking it to an A/C shop. Looking at my wiring diagram, there is a 15 amp fuse someplace in the system. In the diagram is shows close to the isolator, boost solenoid and start solenoid. Those are located on the bulkhead forward of my batteries. For the life of me I cannot find that fuse. Looks like it my be on a wire that is #87. The one and only wire going to my compressor is very hard to get a hand on, but trying to test it with the motor running and A/C turned on there seems to be no volts, but I am not to sure if it was a valid test. I cannot chase the wire because of how it goes into a giant wire loom.
As of now, I am reasonably sure the system still has refrigerant, because the low side shows 90lbs. pressure......
My two questions are.... where is the fuse, and is there a convenient place to apply 12v to the A/C compressor clutch for a test ?
Steve
Steve, my unit is different than yours but I checked to see if compressor works by putting a jumper wire to the one that goes to clutch and grounding it out on something. I am sure that is what I did. My 15a fuse is one of the bus type with 2 small screw threaded connectors on it. I have one for the compressor fan too. Someone will tell you and hopefully I am correct on that test
John
The thing you are looking for is a 12 volt circuit breaker, not a fuse if that helps. You can test for 12 volts in that area with a 12 volt test light or a volt meter and there should be a 12 volt bosch type relay there also.
Got it finally, got the compressor to go and now understand this. Fortunately the compressor clutch is just fine I think my Bosch relay is bad and will go get a new one. However, if that is not the issue, how can I test the low pressure switch?
YAHOO, problem was the relay, put a new one in and all worked as advertised, charges it up with ENVIRO-SAFE R-134a REPLACEMENT and now have dash air again............
Steve
PS about the refrigerant:I went to an A/C shop yesterday and asked a few questions in case I could not get my system working. I asked him if he would charge with this stuff and he said NO. When I asked him why, he said it is because he does not like the stuff. OK, I asked why... he said it can burn. Well I said what is safer, fire or Phosgene gas.... no answer except I just do not like it. Then he talked about compressor oil and I told him it was compatable with any compressor oil.... still said he did not like it. If I were to have had him recharge my system with R-12, he charges $7 an ounce or should I say $112 a pound he definitely liked that......... so I used the replacement Propane/Butane combo at $4.16 a can. Love it......
Steve; on automotive work, I used to just pull the harness connection at the pressure switch and plug in a jumper wire across that connector......to simulate a call for the compressor to run. Also, with the harness connector unplugged, you could just measure for continuity across the pressure switch contacts.....there should be continuity until the compressor sucks the low side down to create near-freezing conditions in the evaporator... then the switch should open (and the cycling starts over again when the vapor pressure of the refrigerant builds back up again)......hence the term CCOT or cycling clutch/orifice tube system. Seems like the most common pressure switch failure mode was to fail "open" ...... (rather than fail closed i.e., shorted internal contacts). When I was doing automotive A/C, you could just unscrew the pressure switch and screw in a new one.......there was a schrader-type fitting in the suction line piping that would seal off the port as the switch was removed.....the new one would depress the shrader upon installation; I suppose it is still the same. Good luck with the repair.......drivin' cool is good. Ed S.
Steve... you had said that you had 90psi in the system earlier and I assume that was R12. Did you draw down that system with a vacuum pump before charging it with R134A?
Dryer change?
Craig
Craig,
90 was with the compressor non functioning, But I had a real cheapo gauge(now resides in my trash can) and set-up for refill. It may have been reading can pressure. When I got the compressor to run and put a high quality gauge on it had about 25 lbs @ 86 degrees. 3 cans of refrigerant brought the pressure up to 45lbs and the dash now blows cold. I did not take a vent temp, or take any readings on the high side, my new set is only for the low pressure side.
No, I did not evacuate the system. This new replacement is 100% compatible with R-12 or R-134a and any kind of oil in the system plus the nice thing is if moisture ever gets into the system, it does not turn the refrigerant to corrosive stuff. Works out nice because I do not have a recovery system and will not let freon go free. I like to be able to do this kind of service on my own. Leaves much more cash in the poke for travel and I get to learn my coach!
Next big projects will be new drive tires. new bulkhead bolts then the severe oxidation and worn out graphics............. We bought it knowing there would be many projects to tackle.
Ed, looks like the pressure switch is a four wire set-up, that is why I was asking about it, Two wire would be a piece of cake. Fortunately that was not my problem....
Enviro-Safe, that's a nice tricky name isn't it. Maybe safe for the environment unless it catches fire or causes an explosion, after all it is a mixture of propane and butane according to others. I haven't analyzed it so I'm not sure what it is. How about a slow leak in a compartment or inside the motor home until a spark sets it off like when someone flips a switch, ignites the stove, etc. A slow leak in your system, that's why you are installing it anyway, isn't it? Many substances make good refrigerants, but until the invention of freon most had some other property like being flammable or poisonous. It's legal to sell it, but it isn't legal to use it in automotive applications; probably the reason the licensed technician would not install it. If you are going to use it, maybe you should put a label at the entrance door and test ports so that the next owner and others will know what they are dealing with. May I be the first and hopefully not the last to wish you good luck with Enviro-Safe.
My coach carries 50 gallons of propane which runs aft to the bedroom furnace and across to the salon furnace as well as to the water heater and the refrigerator. Then there is the liquid propane line that runs to the generator. Then there is the ammonia in the refrigerator itself.
I wonder how flammable R12 and R134A is.
Craig
As I understand it, the commercial refrigeration guys now use a refrigerant called R-420A in equipment that previously used R-12 and it is supposed to be an excellent replacement.
Regards,
The A/C shop I took mine to last year still had some R12 and used that.
Just a quick report of how the new EnviroSafe refrigerant works...... very cold is all I can say. I am totally happy with this alternate method and I found out that this is what is used in Australia.
Cheers,
Steve
Did you happen to try their Stop Leak? My last charge of R12 appears to have leaked off through some tiny, unseen, hole. And the R12 is hard to find and expensive.
No, but I think I may get some......