After I had the AC retrofitted to r134 and charged, a year later it doesn't work. Alsoo have problems with the fan switch. i learned that a loss of pressure(below a certain point, in the system) will disable the compressor from engaging(for those who were wondering) it does that to "protect" itself. All i know is that i measure high pressure when the compressor is off, and I measure low pressure when it's on. This seems backwards to me. could i have a blockage, how can i remove one. also when i added refrig, it did not seem to last more than a month +or-. PLEASE HELP, MY CAR IS COOKING ME ALIVE!
You have a major leak in your AC system plus other problems I suspect. I would recommend getting your hands on a $20 Haynes Techbook titled: Automotive Heating and Air Conditioning. Make sure you get the 2000 edition that covers R-134a and AC conversions to the new refigerant. The book number is 10425. You might even find it at the library. Good luck.
yep, sounds like a leak. Often a retrofit to 134a will leak if you use all the old hoses, etc.. Could be the compressor seal too.. The pressure you see is normal. You are measuring the low side of the system. The usual charged up system will equalize to about the full peg value of the low side gauge. IE: 130-140 lb's etc.. Both the low side, and high side will be the same pressure when off, and equalized. When you turn it on, the low side drops, and the high side raises. It's probably just low, and off on the low pressure switch. You can jumper that switch to check the compressor. Of course, that will only tell you if the compressor actually runs, doesn't lock up, etc.. It could still have a seal leak.. On my 89 accord, the low pressure switch is right next to the power steering canister if I remember right. It's on the high side line. It unplugs. It has two pins, or actually two sockets on the wire end you need to jumper. Stick a jumper wire to connect the two sockets, and that will let you test the compressor. It will also let you run the compressor to charge it back up if you want. Once it gets up to normal pressure, plug the wires back to the pressure switch as normal. You will probably want to find the leak unless you like wasting
134a.. Actually, I'm in the process of trying to do the same to my 89.. I just bought the car a couple of days ago.. I tested it, and the compressor seems to work fine. But... The system was dead empty. Not a good sign.. But anyway, I pulled a vacuum on it, and will see how it holds a vacuum. So far, I see no sudden big leaks. It was holding ok in the short haul.. But I'll check it today and see if any vacuum is still on it. If so, I might give it a shot to see if maybe I can find a leak, and see how long it holds. I'm thinking about using freeze12 instead of 134a though.. I like the pressures of the freeze12 a bit better. Less head pressure, and a tad bit closer to the old freon 12.. BTW, freeze 12 is not the explosive junk they often sell.. It's oked by the EPA.. It's about 80% 134a, with whatever else they throw in to make it act more like R12.. It's not propane .. It does cost more than
134a though.. I've done the 134a retro's, and often had high head pressures.. You gotta be careful not to overcharge.. The head pressure will zoom.. Most true 134a systems use a larger capacity condensor coil than the R12 units to make up for that I think. One month = fairly large leak.. :( Might wanna try some dye detector to see if you can see the leak.. Some also act as stop leak for the seals.. I'm not crazy about stop leak in a a/c system, but in a old leaking beater system, what the heck.. MK
As the others say, it has a leak. The reason the pressure drops so much is that there isn't enough refrigerant available to flood the evaporator. Without refrigerant to evaporate the compressor pulls a vacuum on the evaporator. Usually that causes the compressor to "short-cycle" - run a couple seconds, release for a couple seconds, over and over.
With anything resembling a proper charge the low side port (where you are connected, I'm sure) will read somewhere above atmospheric pressure while the compressor is running. With the compressor off, the whole system will read a higher pressure if there is even an ounce of refrigerant; in each case the pressure corresponds to the vapor pressure of R-134a at the temperature of the part you are measuring.
Bottom line - you need to take this to a pro at this point. You definitely have a leak - it may be where it is impractical to do a "real" repair, like the evaporator, or it may be a seal or hose. If it's the evaporator ask about adding a sealant. Pros hate the stuff because it can gum up other things and/or not work, but if you accept it as a gamble.... Keep a good thought that it's a hose or seal. When the leak is fixed and the proper charge added you should stop cooking.
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