I have my suction side at 55 and the discharge at 110 with outside air at 98. I have replaced compressor and rear expansion valve. The line going to the rear air does not get cold but some cool air comes out of rear vents. Is the rear expansion valve failed cuz the front blows cold only when driving, At a stop it blows warm in the front. I checked the fan clutch and it seems to be working and the Tahoe does not overheat. Any help or suggestions are welcomed.Thanks

 

Sounds like you are low on charge or your orifice is clogged.

Watch the compressor when the front AC is on and the rear off (it should cycle on/off) now engage the rear. If the compressor doesn't cycle with the rear engaged, it's likely that you have a low charge.

Also, did you change the orifice tube and flush the system when you changed compressors? If not, you could have debris in the system, preventing optimal performance.

 

I'd say pull a vacuum on the system then recharge with 2.7lbs of R134a. Also since you changed components you should have added between 100 and 150ml of PAG oil.

Your pressure number is very low for the high side. I generally see 230-250PSI.

 

Muncie21, you obviously have no idea how ac works. There is only one ac compressor....there is nothing in the rear to "engage"

 

If you have a scan tool, see which sensor is turning off tbe compressor, low or hi.

 

Sorry we can't all be genius' like yourself.
I realize there is only one compressor, by engage, I meant turn the rear AC fan on/off, which will increase/decrease the heat load applied to the system, thereby changing overall system pressures.

 

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