I have a 2004 Trailblazer and recently had the transmission rebuilt. Immediately after getting the vehicle back I noticed the problem of everytime the A/C compressor cycled on the RPM's would drop so low that the vehicle would sometimes shut off. After reading the responses for the same problem on this site I removed and cleaned the valve body, now the A/C blows cold again(not as cold as before) and without the engine dying, however now the rpms are still not right, while driving when the A/C is on the rpm's will now shoot up about 500rpm's when the compressor cycles off, same thing when at idle. I am going to try another cleaning. In the mean time if anyone has any ideas I would really appreciate it.