john251

I'm having issues with my AC. at idle, it blows hot (ambient i should say) air, only when on highway driving, RPMs above 2-3K is that is starts blowing somewhat cold air, nothing like it used to.

Here is the sequence of events:

It all started when i had to replace the water flange due to a fairly large coolant leak. Having done that "fun" job, I drove it for a few days, AC is working just fine at this point, when i noticed a strong oil and exhaust smell when i parked. i look it over and see oil all over the bottom of the engince, and find that the crankcase breather hose is torn. So off I go and replace it. (a bit of a tangent, but wanted to give some background).

So I drive it again, and no more oil and exhaust smell, and no more oil all over the engine, but... when i turn the ac on, no cold air comes out. only if I rev the engine up is that somewhat cold air comes out.

Now it seems to me it'd be too much of a coincidence that something just happened to the ac, it's gotta be something i did.

Oh, only other thing I did was spray some degreaser on the engine and hosed it off (engine cold).

The econ light does not come on, and after a while the pipes coming from the evaporator feel kinda cold to the touch..

So, anyone have any ideas/suggestions on what could be going on? I'd really appreciate any help on this...

PS. I dont have a vag so I can read any fault codes, but there's no CEL and the econ light is not on all the time.

any ideas..??

PyridoxineHydrochloride

Either needs a service(recharge) or you have a big air bubble in your coolant system.

road_tripper

you might have splashed oil, coolant or whatever on it. sounds like it could be slipping.

john251

I did bleed the coolant system after the repair, and the temperature is very stable, allways at the mid point on the gage.

I first thought about needing coolant, but my understanding is if it was too low, the econ light would be on all the time. isn't that the case?

john251

I did look at that. At least with the engine running (idle) and the ac on, I can look down and the pulley on the compressor is turning same as the p.s pump.
But I'll take another look and check it for oil on the belt (engine off of course).

thanks

road_tripper

you might be low on refrigerant. buy one of the cheapo cans of refrigerant+gauge from the local parts place (or even wal-mart).

it could be your high-pressure sensor crapped out (common I hear).

follow directions on the can of refrigerant (check pressure first) and see if that solves your problem.

john251

I have access to home/commercial HVAC gages, I guess I can check the refrigerant pressure. Do you know what the off/on high/low pressures should be?

As far as your other suggestion about the hp sensor, don't know much about it, so I'll have to look into that. (where it is, how to test/bypass it, etc..)

thanks

Winston1

Generally, if your car is low on refridgerant, there is a leak. So, you need to remove all the fluid, fix the leak and then put in the proper amount of refridgerant and oil.

john251

You're right, if the refrigerant is low, is due to a leak. I'll have to hook up the gages to be sure. Just from my limited understanding of AC systems, if the refrigerant was low, low enough that at idle there's no cold air at all, I think the low pressure safety valve would kick in and not let the compressor turn on at all. but when the rpms are higher, fairly cold air comes out. The other classic sign of low refrigerant is the evaporator freezing over, and that's not happening either..

thanks for your input, still trying to figure this one out, and really hoping its not the compressor....

john251

Well, finally took it to the audi dealership to get it diagnosed. The came back with it's a bad compressor..! The gave me an quote to fix it of just under $2000 + tax !. The car has 95K miles on it and the mechanic claims that I was lucky I got so much out of it..

Does this sound right to you guys? $2000 to replace the compressor/dryer? Is 95K miles too much to expect an AC compressor to last?..

Has anyone had this done for less?