Just had new Trane 3 ton xl16i with Tam 7 air handler installed 4 weeks ago. We began noticing the outdoor unit starting and sopping frequently about 2 weeks ago. Installer says the unit is stuck in the defrost cycle. They have ordered a new controller board and valve. We hope this fixes the problem, but are worried that this new unit may have suffered damage due to all the cycling. Anything else we should insist they do or check? Thanks for any insight.