Reversing Valve
The valve that switches a heat pump between heating and cooling.
Checking Heat Pump Charge in Heat Mode: What Works in Winter
Why superheat and subcooling targets from cooling don't apply in heat mode, what manufacturers recommend for winter charging, and how to tell if a heat pump is low on charge in heating.
Heat Pump Auxiliary Heat vs. Emergency Heat: When Each Runs and Why Aux Runs Too Much
The difference between auxiliary heat and emergency heat on a heat pump, what's normal, and how to diagnose a heat pump that runs on aux heat constantly or never brings it on.
Heat Pump Defrost: How It Works and How to Troubleshoot It
How heat pump defrost works on time-temperature and demand defrost boards, what's normal during defrost, and how to diagnose a heat pump that ices up or defrosts too often.
Heat Pump Blowing Cold Air in Heat Mode: What's Normal and What's Not
Tell normal heat pump behavior (cool-feeling air, defrost) from real faults like reversing valve, O/B setup, low charge and aux heat problems.