If the inlet (entering) water temperature is outside the operating
temperature range for extended periods the control system may
lock out on high or low refrigerant pressure switch events/trips.
When the control system locks out on a refrigerant pressure
switch event the compressor will stop running, the blower and
circulation pump (on models equipped with factory installed
pump) will continue to operate. This is a hard lock out condition.
The control system is manually reset by cycling power to the
HPWH off and then on again.