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 SW Washington the reversing valve shifts every time a heat pump defrosts on a damp near-freezing morning, plus at each seasonal changeover, so it works through a long heating season. 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 Home Energy Group team — a family-owned HVAC company celebrating 25 years of comfort & care across SW Washington and the Portland metro, licensed in Washington (WA LIC# HOMEEGI003J7) and Oregon (OR CCB# 184255). Definitions inform; an on-site diagnosis decides.
