A/C Compressor will not engage- 6 months old

[jasonran]

Hello all!

First, just to give you guys some history, I replaced my A/c system about 6 months ago. I had the system drained. Then, I replaced the drier and compressor, o-rings, brought it back to pep boys, and had it leak checked and refilled with freon. Also, at that time, had belts replaced. The compressor was supposedly new (AC Delco replacement) bought off of EBay. It's a 1997 3.4.

Problem:

It's been running fine for 6 months- but now, the compressor only engages occasionally. It seems that when it engages, it only does so reliably for a few days, then will stop engaging for a while.. I replaced the fuse, rewired the compressor, and still no luck. Any ideas? The A/C light is green (not flasing or anything) but the clutch will not engage.


I thought also that the R134a might be low (which, as i understand will cause the clutch NOT to engage) but how does one check the pressure if the system is not running? When it's not engaged, the sight glass shows no dye..


HELP!

 

[jasonran]

Also, since it has been hotter, I drained out some of the R134a thinking maybe the system was OVERCHARGED from the repair shop..Still no luck. Compressor will still not engage.

Any ideas as to how much pressure the low side should read when the system is not engaged? Also, what should the correct pressure be for a "full" charge?

C'mon guys- 30+ views and no one has any ideas?

 

[drmorbius]

Also, since it has been hotter, I drained out some of the R134a thinking maybe the system was OVERCHARGED from the repair shop..Still no luck. Compressor will still not engage.

Any ideas as to how much pressure the low side should read when the system is not engaged? Also, what should the correct pressure be for a "full" charge?

C'mon guys- 30+ views and no one has any ideas?

Relax! Many people are still at work and your problem requires specialized knowledge. You may just have a sick A/C relay. You can check that while you are waiting.

 

[jharris2]

C'mon guys- 30+ views and no one has any ideas?

Patience -- you're not encouraging folks to help you with that kind of approach.

 

[RunnerUp]

never buy stuff like that off ebay... when it fails your screwed.

on a side note, when my ac died the ac light wouldnt flash or anything, it just wasnt cold, turned out i had a leak in the evaporator and condenser... 1000$ later, it blows REAL cold

 

[jasonran]

Please excuse my impatience. Didn't mean to piss anyone off...:

Thanks for replying.

How do you check the relay, exactly? Yeah, lesson learned on buying the Ebay compressor, but I was short on cash at the time, and couldn't afford 1000 bucks + to get a professional to fix it. The process was pretty easy, and it's been working for 6 months now. I thought I was ok. Pressure SEEMS OK, but then again, since it won't engage I can't rely on the pressure meter. The low side showed like, 65 with the compressor off. I drained it down to 45 on the low side, just to see if it would resolve the issue. Still no engage. Bleh. Funny thing is, it works SOMETIMES and blows cold almost immediately when the compressor does actually engage.


Again, moderator and others, I apologize for being impatient...I have been fooling with this thing all day, and was getting frustrated.

 

[drmorbius]

Please excuse my impatience. Didn't mean to piss anyone off...:

Thanks for replying.

How do you check the relay, exactly? Yeah, lesson learned on buying the Ebay compressor, but I was short on cash at the time, and couldn't afford 1000 bucks + to get a professional to fix it. The process was pretty easy, and it's been working for 6 months now. I thought I was ok. Pressure SEEMS OK, but then again, since it won't engage I can't rely on the pressure meter. The low side showed like, 65 with the compressor off. I drained it down to 45 on the low side, just to see if it would resolve the issue. Still no engage. Bleh. Funny thing is, it works SOMETIMES and blows cold almost immediately when the compressor does actually engage.


Again, moderator and others, I apologize for being impatient...I have been fooling with this thing all day, and was getting frustrated.

The relay should be in the underhood fuse box. What most people do is find another one in the same box and swap them.

 

[jasonran]

Is that the 10AMP fuse in the fusebox underhood? If so, it's not toast.. So, you suggest i change it with another 10AMP fuse? Funny thing is, the light turns green on the A/C.. Usually, if the fuse is blown, it doesn't even light up. Or, is there another fuse position other than the A/C position i should be looking at? Is it labeled "relay" or something?

 

[jasonran]

OK, swapped the 10AMP fuse for another, no luck.

Just to test, I placed a voltmeter onto the bare wire that runs to the compressor (remember i had to splice it) at the top of the splice... No light. I could have improperly grounded the voltmeter I suppose- I'm no electrician, but it looks as if there is no power going to the compressor! Light on the climate control inside is green. Could this be because the pressure sensor is tripping the power for the compressor or something?

 

[drmorbius]

OK, swapped the 10AMP fuse for another, no luck.

Just to test, I placed a voltmeter onto the bare wire that runs to the compressor (remember i had to splice it) at the top of the splice... No light. I could have improperly grounded the voltmeter I suppose- I'm no electrician, but it looks as if there is no power going to the compressor! Light on the climate control inside is green. Could this be because the pressure sensor is tripping the power for the compressor or something?

It's not a fuse it's the magnetic clutch relay you are looking for.

 

[jasonran]

Sorry, where is that located?

 

[drmorbius]

Sorry, where is that located?

It should be in that underhood box but I have a 4th gen and can't say for sure. There are lots of people here who should be able to direct you with absolute certainty, but they don't seem to be stepping up to the plate. Do you have the manual for the car? It should show a picture in there.

 

[jasonran]

Good news. Found the problem. There was a wire that was exposed for the low pressure sensor. After I replaced that, the compressor engages every time and is still blowing cold..

Thanks for the help, all!