A/C Issue / Question

[warriah]

So we got this Yukon a few months ago and now that the weather is getting warmer I noticed the A/C is not working.
I set it to the lowest temperature at highest speed and had a door open and no change.
So from what I can tell the a/c compressor is not turning on or the clutch is not working since I do not see it turning even though the pulley is working on the belt. I have checked the fuse and relay they are working fine, there is also a correct charge of gas in the system also.

What other steps could I do to test before making the jump to getting a new clutch or compressor altogether?

 

[OR VietVet]

It sure would help to know details of the vehicle and if it has rear a/c. Not ALL 2007 to 2014 GMT900 vehicles are EXACTLY the same.

How do you know the correct charge of gas is in the system? It is a refrigerant and not "gas" for future reference. Unplug the low pressure switch, at the accumulator, and see if the clutch then engages at front of compressor and check to see if it starts to blow cool.

 

[warriah]

It sure would help to know details of the vehicle and if it has rear a/c. Not ALL 2007 to 2014 GMT900 vehicles are EXACTLY the same.

How do you know the correct charge of gas is in the system? It is a refrigerant and not "gas" for future reference. Unplug the low pressure switch, at the accumulator, and see if the clutch then engages at front of compressor and check to see if it starts to blow cool.

Yes, sorry I did not include the details before.
2009 Yukon SLT, there is rear a/c controls as well.

I did unplug the low pressure when I had it running and did not see the clutch engage at all in that time or start blowing cool.

As for the refrigerant, I connected my hose for the refill at the low pressure and the gauge was in the blue area saying filled. Unless this is a wrong reading?

 

[OR VietVet]

My mistake. When you unplug the low pressure switch, you take the connector at end of harness, and cross the two connections and bypass the switch.

You need to read both high and low readings when the clutch is engaged.

 

[petethepug]

Does the Carfax show that the a/c was serviced before being sold?

Is it the a/c with dials for temp control or digital? Did someone accidentally hit the snowflake button that turns off the compressor?

The front & rear a/c are run off the same compressor. If the rear a/c works by controlling it from the rear seat control pad, that will isolate it to the front system.