The air condition unit broke down on Friday July 8th, since it was late we decide to wait until Monday to call for service. We contacted the company that had been doing the maintenance on the equipment to come on to figure out what was going with the Heat Pump (They had installed a new compressor 5 months prior. The technician determined that the reversing valve had a leak and that it would cost $850.00 to install. (He did not think of repairing, and suggested that rather than spend so much money, that it was much more practical to replace it with a new system. The salesmen that was sent for an estimate, gave me prices of 7400.00 to 13000.00. I called cornerstone Air and they came out on the same day, the estimate for similar size equipment was almost $2000.00 less. Since it was now Wednesday and we did not want to go another day without air, the salesmen informed me that they would install a temporary unit to keep us cool until the new equipment could be installed on Friday. It was a God send that I contacted Cornerstone! Jim and Ray were extremely efficient and friendly. They did an excellent job. I highly recommend Cornerstone and will to my friends and family.