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

 

[OR VietVet]

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

The auto temp control does not, as far as I know, control the individual side to side driver/passenger temps. It monitors the inside temp and adjusts the a/c operation accordingly but you still have the separate side to side controls.

 

[Mean_Green]

Blower and Climate Control issues have been resolved.

All fuses appear to be good.

No clutch actuation at all. No detectable response of any kind when pushing the AC button. Have not tried the test circuit yet.

I have a gauge set and two 12 ounce cans of 134. Is it worth trying to gas it to see what happens?

 

[OR VietVet]

What is the static pressure?

 

[Mean_Green]

Dunno. You tell me. Got one of these gizmos, but I have no idea how to use it. Dials remain the same, no change no matter what I do, engine off, engine on, AC off, AC on, knobs open or closed.

I have a vacuum also. Does the yellow hose need to be connected to it, or to a coolant can?

 

[Eman85]

Strange to get nothing, even air would have pressure from the heat in a closed system. Are the valves that attach to the vehicle, red and blue opened, if not you won't get any reading. If they are then open the red and or blue at the gauges and see if anything comes out of the yellow. If nothing comes out of the yellow hook your vacum pump to the yellow and with all of the valves open see if it will pull down into a vacum. If it does allow it to run and see how far it pulls it down, then shut the valves on the gauges and shut the vacum pump off and observe the gauges over time and see if it holds a vacum.

 

[exp500]

If your vacuum pump won't pull it down, You probably need to fab an adaptor to put pressure in from your air compressor, spray some foamy soap around hoses and fittings. Usually the ones over the engine go first, and they are all old enough to be rotten. Still cheap a few months ago at rock auto. I usually change the condenser when changing compressor.

 

[OR VietVet]

And accumulator and orifice. Compressor companies insist on a new accumulator when changing. Flush the system too.

 

[j91z28d1]

honestly I think your compressor is toast and or you don't have the valves on your gauge open.

youtube a quick video on the gauges.

do you have a vacuum pump? if so just spend the 200$ or whatever they are up to these days to get a new compressor, but not a auto parts store. get a sanden, they made a drop in for these trucks, they aren't rebuild and does away with all the failure points. check their website, you can order directly or find the part number and get it someplace else but don't get a knock off sanden design. get the real thing.

Sanden USA

Sanden, Sanden USA

www.sanden.com

it's always best to replace the accumulators/dryer that's on the fire wall and flush the system, but most times you won't be able to. the lines will be frozen up and you'll twit the tubes off the evaporator behind the dash. you'll have to remove the dash to replace that. the orifice tube is worth replacing if it will break free, they usually do but if not. to me not worth damaging the whole system. just throw the compressor on, vacuum the system down and charge with the correct amount of r134 and you'll probably be fine. that compressor is bullet proof and stuff that will destroy any normal compressor just doesn't kill these. in my experience it out lasts the truck.


unless you got time and money to replace everything, if so definitely do it.



this looks like a leaking body seal to me.

 

[Bigfish95971]

Can you jump the compressor clutch wire somewhere up top or do you have to unplug it to get to it?