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AC Not Working!

22K views 31 replies 8 participants last post by  Llacy 
#1 ·
OK, so I figuere to go ahead and repair my condenser, and charged the ac up. And, nothing. I noticed that when I overcharge is the only time the ac clutch kicks in, (over 40 pounds?). its got 40 pounds of coolant and still nothing, and clutch will not engage, Ive checked all the fusses and cant figuere it out for my life! Anybody had probs like this?? Puzzled here, thanks for any info!
 
#5 ·
Gotcha, Yeah I had to pull the condenser, wasnt aware of the air problem, i charged once and blew it out to get the air out, and charged again. But i guess that didnt work, lol. no pressure valve blew, im still holding pressure. Guess I'll be taking it in to a shop!
 
#8 ·
...wasnt aware of the air problem, i charged once and blew it out to get the air out, and charged again. ...
All the web sites that discuss AC system repair include a requirement to use a vacuum pump to evacuate the system, and mention how to recharge it with the proper amount of refrigerant and oil. The equipment to do this isn't cheap, but if you get it wrong, you could ruin a $1000 compressor. Is this the first time you've worked on AC?
 
#9 ·
Yeah, never messed with AC systems before. And I dont believe I'm messin with it again. :duh: Had the voy ripped apart yesterday and just decided to try n charge, since it's FREAKIN HOT!
 
#10 ·
Ok guys, I am just going to put a few cents in the can here, but JUST TO LET EVERYONE KNOW, i AM NOT an AC pro, but I've messed with a few of them.

My cousin had an 04 GMC Canyon with the same issues. His soloution to the problem (he thought) was to try and charge the system. I guess he had a hell of a time before I got there and checked the low side pressure with a good gauge. Turns out he was really high. Now I won't mention how (because it should go to a shop to recover the freon) but we had removed some from the system about down to 35PSI low side or so (about 75 degree day) and restarted the ac and all is well. Sometimes the thing has too much in it. There is a label showing the correct amount of freon and oil that is supposed to be in the system, and an AC shop knows what that pressure should be given a set temperature.

Did you have any leaks, other issues that stopped it from working or was this just something that happend? My dad is having a problem like this on his dodge ram and I still haven't got up there yet to check, but he's got other cars with working air.
 
#11 ·
Yeah, the condensor had a hole in it, but I think I'm just gunna take it to a shop n have em pull a vac on it, hopefully the compressor didnt take a crap on me.
 
#12 ·
In case anybody wonders why R12 (the previous refrigerant that contributes to global warming if it escapes) can't be sold anymore to the end user (or anybody for that matter) unless they have an EPA license, this is why. Too many amateurs without the tools or training. And not even researching the web where sites all say: DON'T DO THIS IN YOUR BACKYARD!
 
#13 ·
hey guys, i was wondering if someone can help me with my ac prob. i got a 03 gmc envol xl, and today i got in it turned on the ac and i got nothing. no air whatsoever. nothing blowing out of the vents, and when i changed to defrost i got nothing either. i switched to rear ac and the blowers were working but it didnt seem like it was cold air coming out the rear vents. i lifted up the hood and can see condensation on the ac line, and i wanna say that the clutch seems to be clicking every now and again. its almost summer and these leather seats are gonna be a pain to sit in if i have no ac. can someone let me know if this is a prob that they experienced and how was it resolved. oh and i tried checking the fuses under the hood as well as under the rear seat and couldnt find anything blown, but i'm also an ameteur at checking for things with vehicles. so please help asap before i melt. thx in adv!!!
 
#15 ·
I am having an A/C issue but I am really clueless as to where to start diagnosing the problem. I already checked the coolant level and that is fine and there are no leaks. I have air blowing out the vents but when I engage the A/C it just keeps blowing the same temp are and the compressor does not kick in.

I know that sounds like it is the compresspor I just want to make sure before I start replacing parts needlessly.

I am sorry if I should have started my own thread, I just saw this one with the title I was going to use and figured why clutter the forum with a second post.
 
#16 ·
I am having an A/C issue but I am really clueless as to where to start diagnosing the problem.
Why guess, then? Take it to a pro.
I have air blowing out the vents but when I engage the A/C it just keeps blowing the same temp are and the compressor does not kick in.
Sure sounds electrical as a first guess. Could even be a fuse.Or the low pressure cut-off switch, a common failure item.
I know that sounds like it is the compresspor
Not yet. Don't apply for a second mortgage yet. It may be a $13 part you can change yourself. Are you going to do the work if it's a minor electrical problem or do you have a mechanic?

Anyway, the two things to check first are front fuse #22 and #30, then the low pressure switch on the receiver/dryer.

Do you have digital or manual controls? If digital, do you have an accurate outside air temp display?

If the refrigerant all leaked out from a leak or damaged part, it needs to be seen by a pro who can find the leak and then replace the bad part, then evacuate the system, and reinstall the proper amount of oil and refrigerant.
 
#18 ·
Great to know you are an enthusiast, and can do the work. So many noobs come here, get lots of advice, then admit they don't have tools or a place to work and they're going to a mechanic after all. I like to get that out of the way first.

To test the low pressure cutoff switch if it's not your fuses, just remove the connector and jump it with a short wire or paperclip. The switch is screwed to a Schrader valve, and replacing it doesn't involve touching the refrigerant. But it's not safe to run around with the switch bypassed in case it REALLY is low refrigerant pressure, since the switch is just trying to save you $1000 on further damaging the compressor. Some folks have bought them used or off Ebay for $300, but if it's just a failed switch, that's cheap!
 
#19 ·
Well being govt. I can use the Auto Hobby shop that is on every post to do my own repairs and if any issues arise they do have mechanics on hand. The shops are nice with their own lifts and a set of tools in each bay, so I don't even have to use my own.

But I am wondering is there a resource I can find like a Chilton manual online so I can see some diagrams and such so I am better able to do my own repairs. Fortunatly for me the repairs I have had to do have all been relatively easy, this A/C as well as the Altenator I need to replace don't seem to bad since they are outside the engine but I have a feeling fate has some interesting things planned for me. Fate always does it seems.
 
#22 ·
A few of us have the Helm, Inc. GM shop manual; mine is for my 2004. We can scan schematics and look stuff up, as time allows. Some folks have official GM on-line access or DVDs, and can cut & paste subsystem replacement sections, if it's something not discussed before on trailvoy. Just ask.
 
#24 ·
well I checked teh two fuses you mentioned Roadie and I think I checked the low pressure switch. I included a pic of what I jumped. But if I jump it will it make the compressor kick on whether or not the A/C button is pushed in the cab or do I need that on. I did it both ways and I didn't hear it at all.
 
#25 ·
You jumped the correct sensor and the truck has to be running with the A/C turned on for the compressor clutch to engage.

Also, swap out the A/C Clutch relay with another. (Relay #44 in the Under Hood Fuse Block)

Could also be the high side pressure sensor, located behind the compressor.
 
#26 · (Edited)
yeah A/C was at full blast and the truck was running of course and nothing. So I should check #44 relay now as well? And if I have to get to the high pressure switch will I have to remove anything to get to it or can I get it from the other side.

I am at work now but I can check all this when I get home.

EDIT: I just checked 44 with 42 and it still did not kick on the compressor. So next will be the high pressure switch.
 
#27 · (Edited)
...And if I have to get to the high pressure switch will I have to remove anything to get to it or can I get it from the other side...
You should be able to access the high side pressure sensor by removing the driver's side wheel.

Before touching the sensor, I would see if you get 12VDC at the A/C Compressor Clutch. Disconnect the clutch electrical connector, (on the front of the compressor between the pulley and the compressor housing) and with a digital multimeter, see if you have 12VDC between the connector's + & - terminals. The Dark Green Wire is 12VDC, the black wire is GND. Again, the engine has to be running and the A/C turned on. If you have 12VDC across this connector, then the clutch coil or wiring is bad. If you don't have 12VDC, the computer is not telling the clutch to engage for whatever reason. (Assuming you have ruled out the low side pressure switch, all fuses, and the A/C Clutch Relay) This could be a bad high side pressure switch, bad control head, or any number of bad temperature sensor(s) in the dash that report to the control head. I believe there are 4 of these sensors hidden in the duct work.
 
#30 ·
I don't have another buddy that has a TB or envoy and yes I did disconnect the battery for 30 mins. Actually I did for 2 hours, because I replaced out the Altenator. Took me 2 hours because I failed to realize I needed to remove that stablizing bracket for the A/C line before I removed the Altenator. I can be thick headed sometimes and not realize something that someone else would've seen plain as day.

Ohh and before it is brought up, the A/C problem was around before I touched the Altenator.
 
#31 ·
I would still check to see if you have 12VDC at the compressor clutch before you take it to a dealer. This will let you know if it is the compressor clutch or something down the line from the control head. Again, when you go to test this, test the harness side of the connector, not the side that is connected to the compressor and the truck has to be running with the A/C on.
 
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