2003 Trailblazer A/C issues

[sntrym95]

Hey all,

Normally I'm posting over in the 88-98 side, but my wife just bought an 03 Trailblazer (4.2L I6, 4x4, EXT), and I'm having some A/C issues. But first, some background...

The water pump went a few weekends ago, and the engine just barely overheated. I replaced the pump, and filled the coolant accordingly, all was well with that.

The problem is that the A/C compressor will kick on momentarily and then kick back off. When it does this, the engine either almost stalls or stalls. I checked the hi/low A/C pressures, and they register at 220/40 respectively. I also jumped the low pressure switch on the condenser, and the compressor still behaves the same way.

So, right after I replaced the water pump, the SES light came on, and the coolant temp sensor was throwing a code, as well as the MAP sensor. I cleared the codes just in case, and drove it. The SES light returned soon, and again the coolant temp sensor registered. I bought a new one, but instead of replacing it, I disconnected the harness for the existing one and monitored the engine. The check gauges light came on and the temp did not register on the gauge. I plugged it back in, and all was well, as expected. So I took the new one back and bought a MAP sensor thinking that would cure the stalling issue. It has helped, as it doesn't stall now, but the A/C compressor kicks on then right back off still.

Any help is much appreciated.

Thanks!
Mike