I had puchased an American Home Sheild Warranty put in a service call and they sent a tech out, he inpsected the unit said it was low on freon, and the timer board was bad. Took all the info and contacted AHS, AHS called me and said they were denying the claim because airhandler and condensor unit was mismatched. The mechanical defrost timer board has nothing to do with it being a mismatched unit. So now I have a unit that ices up on cold night and i have to run emergency heat to defrost my unit at night. What a waste of money, they are a joke.