GMC Truck Forum banner

A/c not working what to check

1781 Views 29 Replies 4 Participants Last post by  Hit Man X
Ok my a/c hasnt been used in awhile. Tried to use it today and 1-5 just blows hot air. Hooked up a gauge on low port and it says freon is full. Noticed my a/c comp clutch isnt engaging at all any. So What should i try checking. Tried fuses and relays no difference. Tried jumping pins on clutch and accumulator plugs still no difference. any help?
1 - 20 of 30 Posts
anyone got an idea
Didn't we already discuss your issues? :hmm:

Posts 11 and down - http://www.gmfullsize.com/forum/showthread.php?t=157864
Never re checked that thread. I have no clue why the clutch wont engage. Idk what else to check which is why im here now lol.
mine was just having probs. on my 350 i just ran a wire from the +batt to the left side of the plug on the compressor and i engauged the clutch. i had to keep messing with the connector and apparently my connector just has a loose wire and mine works now.
I tried that also and it didnt engage the clutch. Id rather not rig it also. If i need to buy a part after i check it i will. Anyone know what to check?
I tried that also and it didnt engage the clutch. Id rather not rig it also. If i need to buy a part after i check it i will. Anyone know what to check?


So you applied 12v directly to the clutch?

Sounds like you have a dead clutch.
Well i went from positive on the batt to + on the clutch. Would i need to also be putting a negative to the - on the clutch to test?
Well i went from positive on the batt to + on the clutch. Would i need to also be putting a negative to the - on the clutch to test?


lol, yeah. Disconnect the factory harness from the plug.

Use a pair of clips and just ground one side of the clutch and hit the other with 12v, I would use an inline fuse but that's up to you. It should lock then.
Fuck, just spin the clutch by hand. That'll tell you if the compressor is bad internally.
If i can spin it by hand its bad?
If i can spin it by hand its bad?


No, means compressor isn't locked... so you could probably just get by with a clutch swap.
hmm ok well let me test this clutch one time. then ill have to hunt for one if its bad. Do i have to drain the compressor and all that to change a clutch?
hmm ok well let me test this clutch one time. then ill have to hunt for one if its bad. Do i have to drain the compressor and all that to change a clutch?


Auto stores carry them new.

Yeah, you get to evac the system... not fun. If the compressor is old, I'd just go with a new one
ok well wired to the batt the clutch worked and i can also grab the clutch and turn it by hand. Should i wire it up and let the comp be on and try to fill with freon to see if thats the prob since you said it wont read with the clutch off?
ok well wired to the batt the clutch worked and i can also grab the clutch and turn it by hand. Should i wire it up and let the comp be on and try to fill with freon to see if thats the prob since you said it wont read with the clutch off?


Well, I'd work backwards from there. Since the clutch checks out... means you have a wiring issue(s) some place. Fuse, relay(s), pressure switches, etc

Also it would help if I knew what truck you have..........
Well i wired it up with the clutch on put freon in and now the comp kicks on when i turn the a/c on so i guess it was low on freon. Is it normal to have moisture around the low fill port for the a/c when putting freon in?

I must have a leak somewhere casue its only been a few years since i put freon in and i barely use the a/c but its never been this low to where the comp wouldnt kick on.
Well i wired it up with the clutch on put freon in and now the comp kicks on when i turn the a/c on so i guess it was low on freon. Is it normal to have moisture around the low fill port for the a/c when putting freon in?

I must have a leak somewhere casue its only been a few years since i put freon in and i barely use the a/c but its never been this low to where the comp wouldnt kick on.


Well would have been better to see if you had any refrigerant to begin with... air we breathe is full of moisture, so if the system had no refrigerant you have tons of moisture in there now circulating with the oil and refrigerant.

Yes, normal to have on the low side as that is the suction/cold side. The high side is hot after compressed and goes to the condenser to cool down.



If you're having issues, you need to fix it right this fall instead of jiveassing around filling it each summer. When you lose refrigerant you also lose oil. Yay. :pow:
Well is it normal for it to be that low on freon in over 2 years? Also my truck has sat up alot not used like a year almost all together.

How would i know if i have a blower problem? it works 1-5 just curious?

Also idk about you but does a/c in trucks get really cold ever? Its cold but i want it to be like subzero temp in my truck with the windows up and a/c on blast lol.
1 - 20 of 30 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top