AC Problem

[Brian Dieckman]

Bought my car almost 6mo ago. (The dead of cold for this area) and I didn't even THINK to check the AC when I did so. When warmer months came, I realized that the AC didn't work. No biggie, I thought, just get it charged.

I took it to a local shop, (very reputable) and let them take a look at it. The tech said that there was not any trace of freon in the system, that I must have a major leak. He charged and dye tested it and it held a charge with no leaks for 3 hours. Great!

Now my problem is this: The Compressor randomly kicks off never to be heard from again. I'll start the car, turn on the air (or the air is already on) and the compressor turns for about three or four blocks, then will turn off. At this point you can turn the air on and off, basically turn every knob on the system and nothing will bring it back. IF, however, you pull the car over, turn off the key and wait about 10sec, then turn it back on, the compressor will run just fine.

The lengths of time here are random, although the first time it happens it's almost imediately...

I'm going to take the car back and ask them to fix it, because they claimed that it ran fine for 3 hrs no problem, which has not happened to me yet. The longest I've gotten it to run is about 10 minutes.

Please help!

-Brian

[strange_trp]

hummm... possibly intermittent problem with one of the pressure switches, but a more likely explanation would be an intermittent fault with a compressor relay. there sould be another relay somewhere close with the same part number on it. if possible, substitute relays to see if problem disappears. (i know this is a ghetto way to diagnose but it works.)
a faulty PCM or sensors going to/from PCM may also be the cause.

if you took it somewhere, the tech would look at pressures just to rule out, but he would spend most of his diagnostic time locating the electrical problem.
in other words, low refrigerant charge is not the only condition that would cause these symptoms. actually, the fact that it will come back on if you turn off the ign switch for a sec is further evidence that the problem is probably electrical in nature.

you said that the tech there used dye and the system held charge for 3 hours. this makes me wonder about why this shop is reputable...
the accepted procedure is to apply monitored vacuum source to system to see if it will keep vacuum for about 30 minutes. did they charge you additional fees for the dye leak test when they could have followed the suggestions of the Society of Automotive Engineers and pulled this vacuum for free as a routine part of the AC charging process? this method helps remove harmful moisture that in air that may have entered the system as well as ensuring the system is completely sealed.

speaking of removing moisture from the refrigerant charge, make sure a new accumulator/dryer is installed (and/or an in-line filter) any time the system has been opened for service to ensure trouble-free operation.

[ June 30, 2002: Message edited by: strange_trp ]</p>

[Brian Dieckman]

:eek:

Wow. Thanks! I've got the chiltons out right now finding the relays in that circuit. Just for kicks I'll replace the relays and the sensors themselves if they're not too expensive. Short of those parts, I assume there's just wiring and the computer to contend with if everything in the system itself is kosher.

I'll certainly ask the shop about the acumulator / filter thing, and I'm going to request a different tech than I got last time too. (He was a gomer. When I took it back the first time to have it looked at, he just drove it into the bay, shook some wires around and of course when he started it, the AC worked.)

I've been poked in the rear THREE times on this stupid leak check bullsh*t. Every time I buy a car without coolant in it, the techs say "oh, there's NONE in there, I'll bet there's one hell of a leak..." Of course, there is NO leak but I pay for the d*mn test anyway. GRRRR :mad:

Sorry. Venting. I'll test and / or replace those parts before I let that gomer molest my car anymore.

-Brian

[Brian Dieckman]

Okay, I havn't taken the car in yet but I've done some ghetto diagnostics and found something pretty interesting.

The AC compressor only disengages if the car is moving. I put on the Ebrake and revved and put the brake on and revved in gear, I can even power brake untill the tires spin, but the compressor stays on. But even if I cruise my parking lot in idle speed, it will disengage after a short time. (the time seems to be random)

So I'm thinking it's GOT to be some kind of a loose connection or something. I'm taking it in the morning and I'm going to ask if they changed the filter and whatnot, it wasn't on the bill.

When this is fixed, I won't be going back to that shop!

-Brian