AC problem 01 Yukon XL 5.3 w/rear air

[LordWayback]

So since I bought this 01 Yukon XL 4x4 5.3 it’s had NO ac. so far I’ve done the belt and relay just to realize the Clutch is toast pictured below I’ve done some light diagnostics the clutch is spinning freely so I’m pretty sure the compressor is working as it should I have a China compressor clutch on the way to see if that’s the problem, any suggestions besides just take it to a mechanic would be awesome I wanna go back to off-roading and not dying on these 110* days with no AC

 

[Scottydoggs]

take the rear inside panel off on the pass side, the blower motor and its controls are there too. theres a actuator, take it off and turn the knob by hand, see if it blows cold now. they dont turn far, so dont go aping on it. 1/2 inch one way to the other tops. you can also have some one turn the cc to hot or cold and see if the actuator moves while your watching it.

if that works the little brain box back there might be bad. thats like a 100 bucks on amazon, actuators are 15 to 30 depending on the brand.

if your clutch is not making noise ac off, leave it alone. its working fine. middle should be very hard to turn, if at all engine off. outer ring the belt rides on should spin freely ac / engine off.

 

[rockola1971]

If im understanding your post correctly you have NO A/C whatsoever front nor rear? The clutch should spin freely if it isnt engaged. The clutch only turns the compressor if it is ENGAGED and at that point you would be trying to turn the whole engine with accessories over by hand if it were. The A/C system has a low pressure switch that actuates around 30 Psi and that is there to prevent a compressor from operating with no refrigerant or oil that is mixed with it that lubes the compressor. If that switch detects the low side refrigerant line below 30psi it tells the BCM to NOT allow the compressor clutch to be engaged. Basically in that case you would have a refrigerant leak that needs to be found and fixed and then vac the system down after a recovery of any leftover refrigerant and then charged once leak checks are performed and passed with the system under vacuum. You need to get a set of gauges on the system to see what your pressure is at on the low side at the very least if not the high side too(they should be equalized with engine not running). First thing I would do is get a valve core tool and snug the valve cores in the low and high side service ports since they are one of the likeliest causes of a leak.

A bidirectional scanner like a tech II can be used to see what state the low pressure switch is at. It can also be used to bypass safeties for just a few seconds to determine if clutch is good or not.

 

[Merc1973]

Rockola1971 is correct. Your system might have no or low refrigerant an can have a leak anywhere. Dont throw parts at it until proper order of diagnosis.

 

[LordWayback]

If im understanding your post correctly you have NO A/C whatsoever front nor rear? The clutch should spin freely if it isnt engaged. The clutch only turns the compressor if it is ENGAGED and at that point you would be trying to turn the whole engine with accessories over by hand if it were. The A/C system has a low pressure switch that actuates around 30 Psi and that is there to prevent a compressor from operating with no refrigerant or oil that is mixed with it that lubes the compressor. If that switch detects the low side refrigerant line below 30psi it tells the BCM to NOT allow the compressor clutch to be engaged. Basically in that case you would have a refrigerant leak that needs to be found and fixed and then vac the system down after a recovery of any leftover refrigerant and then charged once leak checks are performed and passed with the system under vacuum. You need to get a set of gauges on the system to see what your pressure is at on the low side at the very least if not the high side too(they should be equalized with engine not running). First thing I would do is get a valve core tool and snug the valve cores in the low and high side service ports since they are one of the likeliest causes of a leak.

A bidirectional scanner like a tech II can be used to see what state the low pressure switch is at. It can also be used to bypass safeties for just a few seconds to determine if clutch is good or not.View attachment 373911

If the new clutch didn’t turn it on I was gonna rent the gauges from autozone and check pressure levels that graph is really helpful. Clutch spins freely just will not activate from what I was told the belt broke on the AC and they left it like that. I’m trying to narrow down if I need just the clutch and can hold off on the compressor until I get more cash I need Atleast a band aid repair until I can afford a new compressor, from what I can tell the clutch (more coil side)> is damaged. I’m gonna buy some stopleak/detector just to see if it’s leaking in the first place based on the condition of the serpentine belt I have some money on that the belt broke due to poor maintenance.

 

[LordWayback]

take the rear inside panel off on the pass side, the blower motor and its controls are there too. theres a actuator, take it off and turn the knob by hand, see if it blows cold now. they dont turn far, so dont go aping on it. 1/2 inch one way to the other tops. you can also have some one turn the cc to hot or cold and see if the actuator moves while your watching it.

if that works the little brain box back there might be bad. thats like a 100 bucks on amazon, actuators are 15 to 30 depending on the brand.

if your clutch is not making noise ac off, leave it alone. its working fine. middle should be very hard to turn, if at all engine off. outer ring the belt rides on should spin freely ac / engine off.

I’ll check the blower motor thing out it’s blowing air just not cold air ,I think I hear a bit of a noise ac off (doesn’t sound like a squeal but doesn’t sound like a compressor clunk), it’s not activating when AC is turned on if the new China clutch arriving between Wednesday and July 1st doesn’t fix it I’ll also investigate if it’s levels of refrigerant/leaking/bad compressor if it doesn’t get fixed after checking the levels/new clutch I’ll have to take it in because beyond that I’m pretty much at a loss for what it is if that controller isn’t broken.

 

[LordWayback]

Rockola1971 is correct. Your system might have no or low refrigerant an can have a leak anywhere. Dont throw parts at it until proper order of diagnosis.

The parts I ordered were from YouTube “mechanics” recommendations I didn’t hear the relay clicking when the belt didn’t fix it so I tried pulling it and it just fell apart. So I replaced it the clutch was $30 so I said f it I have a $300 part limit before I make it the mechanics problem. So far I’m $80/300 the next step if the clutch doesn’t fix it is refrigerant levels . And if there’s a leak and I need a new compressor it’s probably gonna be a mechanic repair.
This repair project was supposed to just be a AC belt because the previous owner had it “diagnosed” before and got told it would just need a belt. Well low and behold belt didn’t do anything but $20 was worth the attempt $300 was about how much labor would be including diagnostics unless it takes much longer than predicted. If I can fix it under $1,200 then I just saved myself not having to wait for my car sitting at the mechanic and or pay as much.

 

[MassHoe04]

Apologies in advance, if I might have missed something from other posts.

With the AC clutch being an electro-mechanical device...

Have you been able to determine whether the clutch is receiving current on the wire when the system should be calling for the compressor to kick on?

Just trying to rule out the obvious before even more parts are bought.

 

[LordWayback]

Apologies in advance, if I might have missed something from other posts.

With the AC clutch being an electro-mechanical device...

Have you been able to determine whether the clutch is receiving current on the wire when the system should be calling for the compressor to kick on?

Just trying to rule out the obvious before even more parts are bought.

I didn’t break out the multimeter yet because I need to buy a dime cell battery for it to test it. It has a new relay the only reason it wouldn’t have current is a bad vehicle side plug ($5) beyond that no clutch activation would be low freon/refrigerant/bad climate control module (someone suggested) or bad compressor ($180-250) and would have to be done at the mechanic. that’s locked up but it seems I don’t have a problem with the compressor unless it has low refrigerant I shall test all of this after work in like 4-5 hours ,I didn’t even think of testing the climate control module or whatever it’s called because I didn’t get a code or blinking/broken AC light.

 

[MassHoe04]

I didn’t break out the multimeter yet because I need to buy a dime cell battery for it to test it. It has a new relay the only reason it wouldn’t have current is a bad vehicle side plug ($5) beyond that no clutch activation would be low freon/refrigerant/bad climate control module (someone suggested) or bad compressor ($180-250) and would have to be done at the mechanic. that’s locked up but it seems I don’t have a problem with the compressor unless it has low refrigerant I shall test all of this after work in like 4-5 hours ,I didn’t even think of testing the climate control module or whatever it’s called because I didn’t get a code or blinking/broken AC light.

No worries.

HVAC control modules have been known to fail on these trucks.

If you can verify the relay is actually receiving the trigger signal to begin with and the relay is passing that current down the line to the clutch, that would be good to know. Clutch may be good and relay might be good too. But if they aren't getting the go-ahead from the control side of things, nothing will happen at the clutch.

This is my logic (right or wrong) test the critical things that can be tested easily and cheaply first...
Is the HVAC control sending the command to activate in the first place?
Is the command (correct voltage) making it all the way through the wiring harness, to the relay, triggering the relay and out the other side, and on to the end of the line (clutch)?