2012 chevy impala 3.6 no ac

[Nick]

So far Ive not had luck with the ac system in this car.

I can barely get 1 can of refrigerant into the system.

I know there is no blockage, I know the system holds pressure, Ive changed the expansion valve, I know the clutch engages when I turn on the AC.

Both service ports seem to be working fine. The car came with a newer looking compressor also, I changed it out with a compressor from the salvage yard.

What controls the AC compressor solenoid that lets refrigerant in? A fuse? A Relay? Another sensor like the ambient temp sensor?

How can I check that this solenoid is getting power?

Generally when the AC kicks on in a car you can hear the motor get a load on it. Nothing happens with this kicks on.

[tbirdtbird]

"I changed it out with a compressor from the salvage yard."
IMO all bets are off

Did you try the comp that came with the car?

[JohnHere]

I agree with the previous post.

Did you replace the oil in the salvage yard compressor, and what did the old oil look like?

In addition, with a variable-displacement compressor like you have, a system sometimes resists installing refrigerant unless it's under maximum heat load and the compressor is at or near maximum displacement.

That is, on a hot day and starting from a well-held vacuum, you'd want the system switched on so that the compressor engages when pressures reach the engagement point, engine speed ~1,800 RPM, windows and doors open, Manifold Gauge Set hooked up correctly, the refrigerant cans warmed up, and the refrigerant weighed-in.

The electronic control valve, which is pulse-width modulated via the PCM, might be suspect.