There's nothing an Arizona homeowner dreads more than dealing with an air conditioning company. John's takes the fear out of air conditioning work, and I highly recommend them.
My heat pump stopped working on a Saturday afternoon (in the winter), and they were the only company whose phone went to a live person, not an answering machine. They arrived within about two hours, and diagnosed the problem within about 15 minutes.
Even though they seem to carry a variety of parts on their trucks, the one I needed had to be ordered. The technician managed to place the order with a local supply company (even though it had just closed) and arranged a pickup for very early Monday morning. When I arrived home on Monday, the work was done and my heater was back to normal.
I was so pleased with the service that I bought a twice-yearly maintenance contract with this company, which includes discounts on repair parts and labor. They called me for my spring inspection (I certainly would have never remembered to call them), and when they found something that was starting to wear but didn't need replacement, they didn't push me hard to make the repair at this time. Overall, I'm very happy with their service.
They are open 24x7 (actually, they advertise 25x8, but that's a little hokey).