Contour Enthusiasts Group Archives Forums General Troubleshooting A/C dilemna

A year ago my a/c starting blowing just slightly cool air. I figured ok, the car is 6 years old, time for a 134a top up. Bought a kit in the states, with gauge, and emptied most of a 134a can into the system.

When that did not fix the problem, I brought it to a shop. Pressure test, dye, can of 134a, and I was on my way. they did not find any leaks btw...

Since my A/C was still not cold, I figured I'd empty what was left of my 134a can. On max a/c, with the can attached and dumping, it shows 22 psi (too low) when the compressor engages, and 45 psi (a bit high) when it disengages. It would seem to me the frequent cycling I experience is due to a lack of 134a refrigerant (low pressure switch disables compressor). Does this make sense? Any body else experience incessant cycling and lack luster performance? I do not want to wreck anything, but the gauge shows the pressure to be on the low side, at least when the compresor engages...)

Time for another can?

It sounds like you have either a plugged metering orafice or plugged filter dryer.

First of all you need to recover the refrigerent in the system( in the refrigeration trade we are prohibited from venting) then use a vacuum pump to remove all of the non condensables and moisture, then weigh in the correct amount of R134A as specified for your vehicle.

one suggestion is if you do not have all of the equipment for servicing refrigeration systems, it may pay for you to take it to a shop that services ac.

Good luck

Bill

22psi is where mins cycles off low freon. Put the car in the shade, open all vents, put a thermometer in the center vent, max a/c and fan speed and temp knob cold. On an 80 degree day, the compressor will stay on more than off, if it has enough refrigerant. Add some more until it will not get colder. I got 40 degrees. If the car is warm inside already it will take a long time to reach 40. Capacity on my Mystique is 2 cans and 2 ounces= 26 ounces, according to the sticker on the hood. Pressure is about 40 top of blue area on my gauge. If it loses output after that, leaks. I think mine leaks...

Thanks all.

I think i will get another can, and try it, since it seems the compressor is trying, but running into a low pressure condition, triggering the failsafe. If that does not fix it, then its off to the shop.

marco,

I forgot to add one more thing, how is the air flow across your evaporator?

If your cabin air filter is plugged, or your evap is very dirty thus restricting your air flow, this will also cause low suction pressure.

Bill

Haha!

My cabin filter is overdue for replacement. I have one here, so I will replace it and report back. That may be it...

I replaced my cycling switch a couple of summers ago and it cooled like new. All my refrigent levels were normal and it just wouldn't cool down fast enough before then.

How much was the cycling switch? easy to install?

TIA

I forgot, but it wasn't too expensive otherwise I would be complaining about it. Hardest part was getting my hand between the battery and rad mount bracket to remove the old and screw the new switch on. The old one was running the compressor, but not long enough, it would disengage. I jumped the switch and made the compressor run a long time and the car cooled down fast. Other A/C bug I had was the compressor relay. It would flake out from time to time. You could hear the system try to cycle (idle would increase) but the compressor wouldn't engage so it would turn the cycle off. That relay cost about 10 bucks.

Well, I replaced my cabin filter (took a while ), and A/C is still almost zero. I guess my next try will be the cycling switch and the relay.