Intermittent AC Problem... ugh!

[thenukes]

We have a 2001 QX4. It's been regularly serviced and well kept. Only 71K miles. Regardless, the air conditioner crapped out. We took it to the dealer who said we needed the condenser along with tank and switch assembly. In other words, basically a new AC.

Before we took it in, the problem was this....

VERY randomly, the AC would simply not blow ANY cold air. You could start the car... and it would just blow hot for as long as you ran it. Sometimes it only did it for one start. Other times, you could start it several times over a half hour period and it wouldn't blow cold. Then, you could let it sit for a while and it would suddenly work fine. Yes, it seemed that when it was really hot out, it did this worse. But, sometimes it would start fine when it was hot, and then if you turned the car off and on (i.e went into a grocery store).... it would stop working.

Well, we paid $1100 to have the parts replaced and guess what? It's doing the exact same thing. The problem is, it's TOTALLY random. It did it again two nights ago but the dealer was closed at the time. I'm waiting for it to do it again in the daytime, and I'm going to just drive straight to the dealer.

Does anyone have any guesses, here? I've felt all along like it could be related to the climate control, sensors, etc. They said they "tested" the sensors and they're fine. But, it's not like the car blows luke-cold air. It just either blows ice cold or pure hot. There's no in between. It wasn't a slow fade of cold air or anything like that.

So, while I'm waiting for it to act up again, I figured I'd see if any of you experts have theories? Haven't found much on-line thus far. Thanks in advance for any help!

[qship96]

First, I would be sure compressor is engaging when you have the "hot spells", could be something as simple as compressor has a short in wiring{or loose or corroded connector}, not activating the clutch.

If the above checks out, be sure the hot/cold air mix door under dash is opening/closing correctly

Finally check opration of all interior/exterior temperature and all other sensors

You will need the Factory service manual to locate and learn proper testing procedures for each component of the system.....without it you are at the mercy of the technician.....choose wisely

[thenukes]

Great info. I'm going to try to locate a service manual and get myself up to speed more before going back to the dealer. Thanks!

[Andrew224]

I have a service manual. Email me at [email protected] and I'll send you the section pertaining to the Heating and Air Conditioning in PDF format.

Andrew

[thenukes]

Thanks again, Andrew! Very kind of you.

[humhlee]

Andrew224,

Is it possible to send A/C manual to me?If you do, I will be appreciated it.My address is [email protected]

Thanks.

Hummer

[maxnix]

http://www.nicoclub.com/FSM/

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Infinity QX 2000
Modified by maxnix at 5:38 PM 8/31/2008