AC Not working, help troubleshoot.

[Mean_Green]

AC does nothing. Heat seems to work. Blower control is flaky, only works on high, but get some action on low.

Attached a toy gauge mounted on a can of R134 to the Low port with AC turned on. Clutch not cycling. Gauge seems to indicate gas and pressure ... reads in blue range, 25-40

I don't know if I have an AC system problem or an electrical problem, not turning the AC on.

Guidance?


I'm trying to determine where the fault most likely is before I decide if I want to pay for further diagnostics. I've been nickel and diming myself with this machine and I want to at least try to figure things out to some degree.

 

[YukonGTmaster]

If you are having issues with fan speed, I would suspect the climate control switch assembly. I had mine fry out, when I had a water leak that was pooling in the blower motor duct. I would pull the control out of the dash and have a good look at both sides of the connector.

 

[LordWayback]

AC does nothing. Heat seems to work. Blower control is flaky, only works on high, but get some action on low.

Attached a toy gauge mounted on a can of R134 to the Low port with AC turned on. Clutch not cycling. Gauge seems to indicate gas and pressure ... reads in blue range, 25-40

I don't know if I have an AC system problem or an electrical problem, not turning the AC on.

Guidance?


I'm trying to determine where the fault most likely is before I decide if I want to pay for further diagnostics. I've been nickel and diming myself with this machine and I want to at least try to figure things out to some degree.

If the clutch isn’t even cycling you either have a failed clutch, locked up clutch/compressor, fault in the wiring or relay check all hvac fuses and the ac relay (swap with a known working relay) a broken pressure switch would keep cycling when there’s enough freon in the system to run like normal if you want to test your clutch I believe you can feed it 9v and it’ll fire however if it’s functioning as it should but low on Freon/ no pressure it won’t cycle even you can jumper the relay temporarily to see if the clutch engages and if it does you either have a locked up compressor or pressure switch issues like low freon

 

[Eman85]

Good money says all of the essence has escaped and it usually escapes from the compressor. Terrible design with multi part compressor shell that leaks. I've replaced every compressor on every GM truck I've owned with that style compressor.

 

[OR VietVet]

Year of rig would be appreciated. I assume it is the green Tahoe in the pic. Sounds like two problems. Check all connections for problems at resistor and fan and control head and the other problem sounds like low on refrigerant. If you can cross the connector at the low pressure switch at the accumulator, it will let you know if the clutch does engage. can do this with a paper clip. If is low on refrigerant, that means a leak. Large leaks happen at the compressor and hoses/connections. Small leaks at hoses/connections and service ports.

 

[LordWayback]

Good money says all of the essence has escaped and it usually escapes from the compressor. Terrible design with multi part compressor shell that leaks. I've replaced every compressor on every GM truck I've owned with that style compressor.

Good money also says get dorman part#800-955 and a low side shrader valve when I redid my ac I had to change them

 

[LordWayback]

Year of rig would be appreciated. I assume it is the green Tahoe in the pic. Sounds like two problems. Check all connections for problems at resistor and fan and control head and the other problem sounds like low on refrigerant. If you can cross the connector at the low pressure switch at the accumulator, it will let you know if the clutch does engage. can do this with a paper clip. If is low on refrigerant, that means a leak. Large leaks happen at the compressor and hoses/connections. Small leaks at hoses/connections and service ports.

A easier way to force a clutch engage is with a jumper wire on the relay it also determines if there’s a issue between the relay and the clutch sometimes the clutch wires get chewed especially if it’s lowered

 

[LordWayback]

Year of rig would be appreciated. I assume it is the green Tahoe in the pic. Sounds like two problems. Check all connections for problems at resistor and fan and control head and the other problem sounds like low on refrigerant. If you can cross the connector at the low pressure switch at the accumulator, it will let you know if the clutch does engage. can do this with a paper clip. If is low on refrigerant, that means a leak. Large leaks happen at the compressor and hoses/connections. Small leaks at hoses/connections and service ports.

if you complete these 2 connections the clutch comes on cross the 2 shortest distance across legs side to side and it’ll force the clutch on a 10$ flip switch on and off GM 4 leg relay test tool does the same thing and if op takes it to a shop that doesn’t just open the parts cannon it’s the first test if this makes the ac function exactly how it’s supposed to it’s just a bad ac relay

 

[Mean_Green]

I'll try and get a chance to look at some of this stuff next week. Got a simple fuse tester today, so I can check them without pulling. Not sure on the relay yet. Switch panel is weird though. Different color plastc for the mounting bracket behind the bezel, so may have been replaced before. Need to check the blower motor and resistor also due to fan speed issues.

 

[glmoore0001]

If you are having issues with fan speed, I would suspect the climate control switch assembly. I had mine fry out, when I had a water leak that was pooling in the blower motor duct. I would pull the control out of the dash and have a good look at both sides of the connector.

I don't know if mine has climate control or not. I will look at the controls tonight. It has dual controls driver/passenger, temperature, but I am not sure if it actually controls it automatically