A/C diagnosis (auto, valve, buy, replace)

[jimboburnsy]

A/C quit cooling today in my '02 suburban. Belt is fine, fuse is good, A/C abruptly quit (over the span of a day or two) and fan power seems reduced. Could this need a charge or am I likely to need a new compressor? Is there anything else I should be looking at?

[AlfredB1979]

I know quite a few GM products that have various AC system seals go bad and the juice leaks out.

Hopefully, you are looking at a shop visit for a vacuum job and recharge/reseal.

You didn't mention any horrible noises, so I hold out hope that the compressor is still in good shape.

[Deez Nuttz]

Pop the hood, and turn on the a/c, see if it is "short cycling" or the compressor is turning on, then off, then on, then off...

This means the charge is low.

If so check around the compressor and such for an oily residue, which can pin point a leak.

Or you can have a shop top it off and put a can of ultraviolet dye in it, then bring it back a few days later and they use a special ultraviolet light to see if there's any green...which means a leak.

HTH

[jimboburnsy]

Originally Posted by Deez Nuttz

Pop the hood, and turn on the a/c, see if it is "short cycling" or the compressor is turning on, then off, then on, then off...

This means the charge is low.

If so check around the compressor and such for an oily residue, which can pin point a leak.

Or you can have a shop top it off and put a can of ultraviolet dye in it, then bring it back a few days later and they use a special ultraviolet light to see if there's any green...which means a leak.

HTH

The compressor isn't cycling at all. Nothing. The cam is fully engaging the belt but it's just free-spinning, if that makes any sense. There is no difference between "A/C Activated" and "A/C Deactivated" at all. Clutch out? Electrical problem? Does that sound like a new compressor? I'll check all the electrical connections, but I'm fairly certain that isn't the problem.

[johnfrisco]

It's hard to say. It could be an electrical connection. I had that happen on my 96 Altima--easy fix.

More likely it is a bad compressor or your freon is so low that the compressor won't kick on.

I would buy 2 cans of R-134A to see if you can get your compressor to kick on. At least that will give you a better idea on where your problem is: http://www.amazon.com/Arctic-Freeze-Trigger-Dispenser-14/dp/B000ALZDQK/ref=sr_1_1?ie=UTF8&s=automotive&qid=1268273445&sr= 8-1 (broken link)

Any Auto Parts Store will have something similar.

[jimboburnsy]

Originally Posted by johnfrisco

It's hard to say. It could be an electrical connection. I had that happen on my 96 Altima--easy fix.

More likely it is a bad compressor or your freon is so low that the compressor won't kick on.

I would buy 2 cans of R-134A to see if you can get your compressor to kick on. At least that will give you a better idea on where your problem is: Amazon.com: Arctic Freeze with Trigger Dispenser (14 oz): Automotive (http://www.amazon.com/Arctic-Freeze-Trigger-Dispenser-14/dp/B000ALZDQK/ref=sr_1_1?ie=UTF8&s=automotive&qid=1268273445&sr= 8-1 - broken link)

Any Auto Parts Store will have something similar.

Is that junk from the auto parts store with "leak stop" going to mess up my A/C?

[wheelsup]

You don't know if its a leak or not. Could be the clutch. From my experience when the clutch goes it's more cost effective to replace the compressor. However it quitting abruptly makes me think of an electrical issue. Might be time for an a/c pro.

PS Yes that stuff is crap if you plan on keeping the car don't touch it.

I replaced the a/c compressor, dryer, and expansion valve in my wife's Jetta for $350 DIY.

[jimboburnsy]

Originally Posted by wheelsup

You don't know if its a leak or not. Could be the clutch. From my experience when the clutch goes it's more cost effective to replace the compressor. However it quitting abruptly makes me think of an electrical issue. Might be time for an a/c pro.

PS Yes that stuff is crap if you plan on keeping the car don't touch it.

I replaced the a/c compressor, dryer, and expansion valve in my wife's Jetta for $350 DIY.

Mystery solved. Big honkin' hole in the evaporator.

Evidently my car is smarter than I thought and the dealership was able to pull a code that indicated "evaporator problem". The dealer recommended replacement and gave me a pretty huge quote.

I asked them to charge the system and to add some dye to confirm the problem. Charge lasted about five days and there was a pretty strong R-134A odor every time I ran the A/C.

I went through the Chilton manual to educate myself about evaporator unit replacement, since this has helped me spot b.s. in the past. The Chilton manual provides instructions for some pretty advanced car surgery so I was a little forlorn when the evaporator unit tab simply said "This is really hard. Seek the assistance of a professional."

Evidently the whole dash assembly must come out and one of the tools involved to remove the damned thing is an angle grinder.

I went to a "family" mechanic for the actual replacement. He recommended replacing the heater coil assembly while the dash is apart. It seems like a reasonable recommendation since the labor is basically the same, but I have that little "milkcow" marquis lighting up in the back of my head. He's done a lot of work for my extended family but I don't really have the same relationship with him that his original client base had (and my family, while generally pretty handy, is also generally car illiterate - including and/or especially me), if that makes sense. Is that as reasonable as it sounds?

[M3 Mitch]

Funny I was just about to suggest a new heater core as well as the evaporator. I would get OEM quality or better.

This is a pretty extensive job in most cars, you end up taking the dash apart pretty far - typically you have to take the evaporator out to get at the heater core, I would definitely spring for the part and the very little labor added to do this.

Agree with wheelsup that the "charge and seal" stuff is not to be recommended.

[NJGOAT]

I concur with Mitch. If you are going to replace the evap, might as well replace the heater core as well. The heater core is one of those cheap parts that costs a lot to replace.