All City Heat and Air came out and installed a new system for me 2 years ago. We have had maintenance contracts on the system since then. Their professionalism is what stands out to me about them. It's under a service contract so it's covered by the contract. They come out every 6 months and the price covers the life of the contract.
I would recommend family and friends to very definitely consider them, and I will use them again. They are certainly very responsive, and they have been very willing to work with me. I live in Florida, but the house is in Charlotte so they have worked through some scheduling issues and some other issues with me that have been mutually satisfactory.