ao-smith HPTU-66N Heat Pump Water Heater Error Codes
HPTU-66N Error Code Reference
Section titled “HPTU-66N Error Code Reference”Heat pump + electric backup, 66 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 |
| HP9 | Communication error between heat pump and tank control board |