I don't know if I trust these people 100%. We had a compressor motor go out and they replaced that and we signed up for a service, a day later we heard a knocking and the when the motor was replaced the fan was misaligned so they had to come back out and fix it and they said they thought it was like that before.
6 months later when my 2nd check up came (free under the service agreement) they came out and I wasn't home and they told my wife they we were low on coolant and there was a leak in our condenser. They just wrote on the receipt leaky in the compressor needs new unit call us $5k.
I never called but they sent me a brochure in the mail a couple weeks later.
Of course now I'm paranoid but the AC has been working fine.