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Can't find leak

erikrichard on Sun August 12, 2012 11:12 PM User is offline

Year: 2000
Make: chevy
Model: Cavalier
Engine Size: 2.4
Refrigerant Type: 134
Ambient Temp: 75
Pressure Low: 35
Pressure High: 40
Country of Origin: United States

The wife's Cavalier AC is acting up. Worked fine for 6 years up until 2 weeks ago when it was blowing hot air. I put a can of freon in it and it was cold, for about 2 days then it was blowing hot again. I borrowed my neighbors sniffer, and we couldn't find a leak anywhere. With the compressor running the gauges showed 35 lbs low side 40 lbs high side. I then put in a can of freon with dye, and the high side went to 175 low side stayed at 35. That night could not find a any dye anywhere in darkness. Two days later it was blowing hot again, still can not find dye or get the sniffer to react to anything.
Today I got bottom half of the the heater core/evaporator enclosure off, haven't taken either component off yet. My blacklight picket up some bright whitish/yellowish color around the bottom seam of the evap and the plastic I took off is very dusty which could be oil residue, but I'm not entirely convinced enough to pull it out and replace it. Any advice much appreciated before I take any components off.

Edited: Sun August 12, 2012 at 11:14 PM by erikrichard

GM Tech on Sun August 12, 2012 11:18 PM User is offline

Compressor shaft seal is number one location- folowed by the compressor belly leaks--this is from my experiences of over several hundred v-5 compressors...

Evaporator problems ended in 1994- haven't seen a bad one on a J-car since then....

So if I were you, I'd play the odds...

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

erikrichard on Sun August 12, 2012 11:36 PM User is offline

So your advice is to put the interior back together and replace the compressor and dryer? wonder why the sniffer won't react at the compressor with a leak big enough to lose a can in 2 days? is that common?

Dougflas on Mon August 13, 2012 7:38 AM User is offline

Some sniffers don't pick up R134. What kind and model is it?

erikrichard on Mon August 13, 2012 11:00 AM User is offline

It was my neighbors, a retired mechanic who suggested it may be the evaporator. To show me what the sniffer does he let out a tiny stream from the 134 can we had just emptied into the system and the sniffer went nuts when placed at the opening.
I have another question - after putting a can in when the ac was cold I put my hand under the evaporator drain tube and cold air was blowing out - is that normal?

Edited: Mon August 13, 2012 at 11:11 AM by erikrichard

Dougflas on Mon August 13, 2012 12:20 PM User is offline

Yes, cold air can blow out the drain tube. Sometimes, you have to plug the drain tube with the AC system off to pick up a leak. Then after the vehicle sits a few hours, remove the plug and then use the sniffer. This also prevents the condensate water to fall onto the sniffer's sensor.

pippo on Mon August 13, 2012 3:40 PM User is offline

beware of the arrival

pippo on Mon August 13, 2012 3:44 PM User is offline

Man, I empathize with you on chasing an elusive leak. Just chased one for months, then finally found it. It was the cheap rubber Honda used for the suction line. Sheesh. Sniffer never would found that, not even the good ones that detect down to 100ppm hc,s.

I can't believ no dye stains after loosing a full can do r134a in a day or two.....

beware of the arrival

erikrichard on Mon August 13, 2012 7:18 PM User is offline

I'm inclined to just replace all components - evap, cond, acum and compressor, all seals and the orifice tube because I'm just not up for troubleshooting and redoing anything. I can get all that shipped for under $500. Any other suggestions on leak finding before I place the order?

Dougflas on Mon August 13, 2012 10:34 PM User is offline

After replacing all that, you'll be pissed if you find you have a leaking hose.

Leggie on Tue August 28, 2012 7:55 PM User is offline

Evacuate, pressurize to 150 psi with nitrogen. Go at it with soapy water and look for fizzing. Compressor shaft seal, all connections, condenser, etc.

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