a/c leak

[ace58]

Has anyone had problems with either the front or rear a/c evaporators? The mechanic has gone over all exposed lines with sniffer and all is well. The undercarriage is clean and the lines and clamps are mint to the rear unit. Does this mean the evaporator(s) are leaking?

[kevin77]

I would also check out the compressor to see if it is leaking - I have the v-5 compressor on my suburban and at some point, the design for the seals were changed because they would leak after a while. I could take the belt off and wiggle the pulley from the compressor and actually hear the compressor leak.

Kevin

[ace58]

Thanks for the reply. The compressor and lines are tight. I actually changed the big line that runs across the top to the firewall when replacing the engine.

[HowieE]

Sniffers are OK for working on fixed AC units but not too effective on cars and trucks, too much air flow.
I have a known leak in my system and can not pick it up with a sniffer.
How fast is the system leaking, a # per season or the whole load in a few weeks? You would be better off to Die the system and let it leak for a while and then look for the leak than pulling the system apart and just throughing money at it.
My leak is around the bolt the holds the manifild to the compressor. There are 2 O ring seal below the manifold and only 1 bolt through the center as a hold down. It leaks about a 3 and a 1/2 per season.
Another factor, auto AC often leak while cold and will seal when at operating temperature making it even harder to find when operating.

[ace58]

The system leaks out in a matter of days. The shop has repaired twice and each time within a week, system is "empty". The compressor stops working when refridgerant is not present as a safety, I was told.

I will ask about a die test. Thanks for the help.

[HowieE]

I should have mentioned. If you go for a Die Test ask them if they will put the die in and just enough nitrogin to overcome the low pressure switch. You most likely still have some freon in the system so once the low pressure switch allows the compressor to operate it will push the die through out the system. Operate the system for 5 or 10 mins and then let it sit for a day or two. Any leak of that size should push out the die and no reason to waste the cost of a Freon charge again while looking for the leak.
Once found the system will have to be evacuated anyway and the nitrogin will come out.

[BUZZ]

Is there any oily film on the comp clutch? If so compressor.

[diesel65]

A common area I have found to leak on the Suburbans with rear air is the big pipe going to the rear evaporator, it is in front of the rear tire.
There are plastic sleeves on the pipe where the clamps are, the sleeves tend to trap moisture and I usually find a pin hole behind the sleeve caused by corrosion.

[ace58]

Thanks for the help. Got a busy weekend applying this info.

[GMC Hauler]

I recently found that mine leaked at the high or low presssure fill connection on top of the conpressor (i think it's high, but i am away from home for a few months and can't remember). I got a new valve, which included a new o-ring from the dealer about $10, refilled the system, and it's now running ice cold without leaks.

Does your dust cap release any pressure when you remove it? (the cap is the black one on top of the compressor, where you connect to)