We would highly recommend North Valley Mechanical.
Our tech, Chris, came on time, was very professional, patiently answered our Qs, and most importantly - knew his stuff. He was able to de-bug our issue. And once he knew exactly what was wrong, went and got the needed replacement parts and finished the job.
Our A/C unit is functional again and haven't had the intermittent stoppages that we did previously. Since we had warranty, I specifically requested NVM as the contractor through whom we wanted our repair work done - after reading the reviews on Yelp and Angies list. And we were very satisfied.