Hey all.

Like the subject says, my air conditioning is not working; it does not blow cold (or even cool) air.

2007 Sahara - 131,xxx miles. Owned since '08.

When I push the AC button (blower fan on, obviously), I don't hear my usual 'clunk' from the compressor engaging. I verified, the compressor does engage.

When I shut the AC button off, there is a 3-5 second hiss behind the radio area of the dash. Like something is depressurizing. I don't recall hearing it - at least to this extent - in the past.

Yesterday, trying to troubleshoot this while driving, I engaged the AC button and I got that hiss for a good minute or two until I shut the AC button off again. I haven't been able to replicate that since.

Any ideas?

I'm guessing I took a rock to the condenser and my freon (or whatever) is gone. Not sure. Hoping there is some sort of pressure switch or valve that's on the fritz instead.

 

Quick follow up question: No part of our AC system runs off of engine vacuum, correct? (IE: old school vacuum controlled doors and what not?)

The hiss I heard sounds like a vacuum leak off one of those old 1/8" vacuum lines. The hiss lasts for a bit, then fades off.

 

Are you sure its leaking? It may just need to be recharged.

 

Check that freon is full. If empty there is a leak some where. Check that compressor is working. If you can get that to turn on check switch in the dash.

 

Thanks guys --

How do I check the freon level? With one of those recharge canisters with the gauge on it?

Secondly, does freon have an odor? I haven't noticed anything funny, but not sure I should.

 

Yeah, I would say that a simple recharge would fix the problem.
There's kits at Autozone for about $49.

 

I'm really not familiar with AC systems... but to me,... if I was low on freon, wouldn't it have to have gone somewhere?

That's the only reason I'm considering that there is a leak somewhere.

I did some reading on the side and just got in from looking things over. I was looking for oily residue from a leak.. and literally found no sign of anything out of the ordinary. I'm not sure how far in the dash the evaporator is buried, but that was the only item I didn't check.

I did notice that my compressor wasn't engaging consistently. I'm not sure 'when' it should be engaging - but I know it's keyed off of outside air temp and other system temps. When it did engage, I got the constant hiss from the dash.

 

My 08 (over 110,000 miles owned since new) never did get cold (still doesn't) just a little cool. I do get the hissing you hear, have since picking it up. I would e happy to find you have an issue that is fixable, I may be suffering from the same thing.

Jeep - There is NO substitute!

 

You are correct with your assumption that the refrigerant went somewheres and looking for oil residue is a good place to start.
There are several common places that refrigerant leaks occur; service connections, system O rings, compressor shaft seal, condenser coil and evaporator coil.
The only way to verify what is going on would be to have someone that has a refrigerant gauge manifold connect to the service connections and verify what the system pressure is when the compressor is not running and then jumper out the LPCO to see what the system pressure is while the compressor is running.