Service manual for Amana AC unit

[Millerwright]

Hi, I am in need of a technicians service manual for a Amana AC unit model # PTH 128 G series ( heat pump)
My problem is the compressor won't come on while in the heat mode. Works fine in cool mode. The diagnostic mode shows nothing wrong so I'm thinking its a temp. set point or limit preventing it from starting up.I would like to revert to factory defaults and hopefully it will function normally after that. I would greatly appreciate your input and help in this matter and thank you for your time. [email protected]