ao-smith HPTU-50N Heat Pump Water Heater Error Codes

HPTU-50N Error Code Reference

Heat pump + electric backup, 50 gal

Error Code	Fault Description
HP1	High-pressure safety trip
HP2	Low-pressure safety trip — possible refrigerant leak
HP3	Compressor overtemperature fault
HP4	Ambient air temperature sensor fault
HP5	Evaporator (refrigerant) temperature sensor fault
HP9	Communication error between heat pump and tank control board