A/c Compressor Troubleshooting

[carl425]

I'm working on a friends '03 Tahoe whose A/C isn't cold and I'm puzzled. The compressor won't run even with the pressure switch jumpered. I ohm'd the coil at the connector that points toward the ground on the compressor and it has about 4.5 Ohms and good continuity. The gauge reads 100PSI on the high side so its not low. Nobody's serviced it all so it shouldn't be over serviced. The light comes on on the control inside. Any help is appreciated!

[ZZ327]

I dont think you need to jumper the pressure switch, they are automatic reset. But I could be wrong.

 

The only way to tell if youre low is to have the AC switch on HIGH and the engine running. Then give it a shot of freon and see if it does anything. It could have a leak and went out on the low pressure cutout.

 

and you should charge it up LOW side only ( the big port) near the accumulator can.

[carl425]

I dont think you need to jumper the pressure switch, they are automatic reset. But I could be wrong.

 

The only way to tell if youre low is to have the AC switch on HIGH and the engine running. Then give it a shot of freon and see if it does anything. It could have a leak and went out on the low pressure cutout.

 

and you should charge it up LOW side only ( the big port) near the accumulator can.

 

What should the pressure be on the low side with the A/C on high? If the pressure is good and the coil is getting voltage to it AND the coil ohms at 4.5, what else can it be?

[Indy]

It should be 25-45psi.

[496 XL]

Have you tried turning on the a/c and check at the compressor for 12+ voltage,I see you ohmed it but said nothing about the compressor actually getting the required volts to engage the clutch and turn it. Just a thought.

 

rgds,

Perry

[carl425]

Have you tried turning on the a/c and check at the compressor for 12+ voltage,I see you ohmed it but said nothing about the compressor actually getting the required volts to engage the clutch and turn it. Just a thought.

 

rgds,

Perry

 

Yes, I have and yes it is. Good question though, I should've mentioned it to begin with.

[carl425]

Have you tried turning on the a/c and check at the compressor for 12+ voltage,I see you ohmed it but said nothing about the compressor actually getting the required volts to engage the clutch and turn it. Just a thought.

 

rgds,

Perry

 

Okay, I've done about everything I can think of and results are as follows, all tests were done with vehicle running and A/C on high:

The compressor is getting about 13.8 volts at the connector.

I've tried jumping the pressure switch on the accumulator

I ohmed the compressor and it's about 4.5 (is this okay, or should it be higher)

Measured the charge on teh low side and it was WAY over-serviced by somebody in the past (100 psi!)

I let out (excuse me, reclaimed) enough pressure to get in in the blue (25-45psi)

Swapped the HVAC relay in the engine compartment relay box

Checked all fuses

 

After all that I'm pretty convinced it's the compressor. Does anybody know of anything I missed?

[ashleyrihner]

Unfortunately - I do not know the answer to your question. I, too, am having a/c problems with my 2001 Tahoe.

 

*** Answered to meet 5 reply thread so that I may post a question ***