a/c not working, running out of ideas

[Prorac1]

My a/c has mysteriously quit working again. We drained the system, filled it with the correct ammount of r134. The hi and low pressure readings are good. The pressure switch was switched with a known good one, so that was eliminated. The compressor wont come on, and neither will the fans. However the fans do work when the engine reaches the determined operating temp to command them on, so its not the fans. Im out of ideas, what could this be. Could it be an ECM issue? It did this same thing around the 4th of July, and than just mysteriously started working again, until yesterday, lol. Maybe it has a phobeia of holidays? IDK, but any input would be appreciated. Im COMPLETELY out of ideas. Thanks Eric L

[Fastbird]

Have you tried just a simple disconnect of the battery? I had a similar issue once and once I disconnected teh battery and hooked it back up it reset everything and I was fine after that.

[Prorac1]

Heres the strange deal. I unhooked the battery for about 15 or 20 minutes. The A?C didnt work still. The clock on the radio reset, but the radio presets did NOT reset. Did I not leave the battery disconnected long enough? I only disconected the hot, should I disconnect both + and -? Thanks Eric L

[Fastbird]

Just disconnect the negative terminal. That's always worked for me. If anything, taking it completely off the car should do the trick.

I can't remember if there's an A/C compressor relay, but if there is, try swapping it with a known good relay.

[Tarheel'Z']

doesnt the compressor need to run to get the pressure readings? im asking?

[Prorac1]

I swaped relays twice. When we checked the a/c pressure, it was after it started working again mysteriously, lol. Im going to go outside and REconnect the battery and see what happens. If that dosent work, I might throw in my spare ECM. Ill be back in about 5 min, lol. Thanks for all the input. I know that this has been an F body problem for years. Maybe we can put our heads together and come up with a cure. Thanks again. Eric L

[Tarheel'Z']

what was the original problem?? sounds kinda like its low in freon to me? was previous problem a freon leak?

[Blubird]

That's weird cause the fans should kick on if the system sees pressure.are you sure the compressor is good ? Or maybe the wiring going to it has a break or a bad wire

[Prorac1]

The original problem was that the a/c compressor would just cut out when ever it wanted. The freon level is not low, thats been checked. I just reset the computer, still no fans or compressor kicking on. I have also checked the wiring going down to the compressor, and they are all good. How do you jump the relay? Maybe that will shed some light on things if it will work when I jump it. But I cant remember how to jump a relay, lol. I think im going to go out and swap ECMs now. Eric L

[Prorac1]

I just swaped the ECM, no luck. No fans, no compressor...........nothing. Any ideas. Eric L

[Fastbird]

If you can, unplug the harness at the compressor and test for voltage across with the A/C on. There should be voltage present across there......if you need a spec I'll try to find it.

[Prorac1]

Yeah, ill need a spec. Is this with the car running, or can I do this with the key on only? Cause I dont think id want to try it running, lol. Thanks, Eric L

[95formula383lt1]

jump the relay by taking the cover off the relay and squeeze the brass tab on the side. u had the same issue but i had a sensor that was unplugged ac would only work when jumping the relay there's a thread about it....

edit mine was the temp sensor in the evap box. maybe this thread will be of use to u.


http://ltxtech.com/forums/showthread.php?5493-A-C-Compressor-will-not-turn-on-unless-jumped-at-the-Relay

[Prorac1]

OH.....................MY......................... ....GOD. Now, im REALLY confused. I did as fastbird said. I pulled the plug on the compressor, tested voltage with key off as a control. It read 0, good. I tested it with key on, it read 0, kinda as i figured. I started car, multi meter read 13.4, I says, darn, sounds like its an electromagnet in the clutch, damn. So I turn the car off, and plug it back in. Just for grins, I start the car BACK up, turn the AC back on, and CLICK...................................The DARN compressor kicks on, ARGHHHHHHHHHHHHH. What could it be? A bad connection at the compressor? I disconnected the battery and pulled all the fuses earlier to do a master reset. I even swaped ECMs. WTF. Yeah, im glad its working, but if I dont figure out why, im no further than i was before. DUDE. lol, that is all, lol. Eric L

[Chris]

Measure the gap on the compressor?

What does the plug look like?

Put some Dialectic grease in the connector

[Prorac1]

The plug looks good, I have grease on the connector, and how do I measure the gap? Would that cause it to randomly turn on and off? Thanks. Eric L

[Chris]

Yes if the air gap is to high

http://autorepair.about.com/library/faqs/bl168i.htm

An idea of how to do it

[Chris]

Yes if the air gap is to high

http://autorepair.about.com/library/faqs/bl168i.htm

An idea of how to do it Ill look up the spec in a little bit