Definition
A reversing valve is the solenoid-controlled valve in a heat pump's outdoor unit that switches the direction of refrigerant flow, changing the system between heating and cooling. It also shifts the system into cooling briefly during a defrost cycle. A stuck valve or failed solenoid can leave a heat pump blowing cool air in heat mode.
Why it matters to you.
In Central Kentucky the reversing valve shifts at every spring and fall changeover and every time a heat pump defrosts on a damp winter morning. Cool air from the vents in heat mode may be a valve problem, or simply a normal defrost.
Practical guidance.
Confirm the thermostat is set to Heat and wait several minutes, since defrost can briefly blow cooler air. If it keeps blowing cold, call a licensed technician; testing the valve involves refrigerant pressures and live electrical circuits.
About this definition
Written by the Feistritzer Heating & Air Conditioning team — family owned and operated in Danville since 1976, Kentucky HVAC license M02584. Definitions inform; a whole-system diagnosis in your home decides.