2010 Tahoe ac help

[2010blacktahoe]

Ac stopped blowing cold. I’ve checked the pressure at the low side and it’s around 35 when the compressor clutch is engaged. Also changed the low pressure sensor and relay. The compressor will engage when you turn the vehicle on, runs for about 7-10 seconds, then kicks out. It may take 10 minutes for it to kick back on if it does. I jumped out the relay to make the compressor run so I could get a reading on the Freon level. When I did this, the air blew cold. There is no lack of air flow from the vents, and it blows out of the proper vents when you select them(dash, floorboard, defrost, etc.) It has the auto controls with dual temp ( driver, passenger) and rear air. What am I missing here? I feel like whatever should be telling the relay to close is not functioning properly

 

[96-2D-Hoe]

Sounds like it's short of gas.

But
Are you saying it runs steady at 35PSI without dropping and the compressor cuts out? If so what is the high side doing when it cuts out?

 

[2010blacktahoe]

Steady at 35 when the compressor is running, but the compressor is not cycling like normal. It runs as soon you cut the truck on, then kicks out. It takes several minutes to kick back on. I bypassed the relay to keep it running steady so I could get a pressure reading. Not sure about the high side. I’ve only got one of the gauges that come on the cans of Freon. I’m gonna get a real set of gauges tomorrow so I can check both sides

 

[96-2D-Hoe]

Sounds like a sensor cutting it out. I'm not sure where the low pressure switch is set to on your truck but that would seem to be the most likely option and in which case it is short of gas.
But still could be something else. I don't know your generation truck but someone will.

 

[2010blacktahoe]

I changed the pressure switch because I read that that was a lot of people’s issue. If it was actually low and the pressure switch is sensing low pressure, I don’t understand why it allows the compressor to engage when you start the truck, and occasionally kick back on.

 

[gpracer1]

I hate to say "you need a Tech II" but it really helps with AC permissions and what may be inhibiting or commanding your AC clutch to engage or not......that is assuming the wiring, connectors, clutch is good. You can even read the pressure on it and command things on and off manually bypassing the AC controls to rule them out.
High and low side readings also help.

 

[gpracer1]

I changed the pressure switch because I read that that was a lot of people’s issue. If it was actually low and the pressure switch is sensing low pressure, I don’t understand why it allows the compressor to engage when you start the truck, and occasionally kick back on.

As long as there is even a little liquid R134a in the system, it will read about 75-90 NOT running the AC on both low and high sides (depending on ambient).
As soon as the compressor engages the low side will drop, the colder the inside of the vehicle gets the more it will drop, also RPMs will pull the low side down. Once you start driving and get good airflow the low side will also start to drop a little along with the high side.
If the low side gets below the low cut off it will turn off the compressor till it sees the re-engagement pressure on the low side switch.
If your freon level is normal and it is kicking off, you may have a high side cut out issue. Bad switch, no air flow, bad fan, etc. Lots of things to look at if you know what you are doing.

 

[OR VietVet]

It sounds like it is low.