What does HP-04 mean?
The unit says heating but the supply air is colder than return (or the opposite in cooling).
Why does it matter?
A stuck reversing valve or a wrong mode point means the unit works against the space every time it runs.
What should you do?
Verify the reversing-valve solenoid and coil, the mode/changeover point wiring, and the thermostat configuration.
How Energy Agent prices a finding
Written by Pelorus Engineering · Brent Waluzak, P.E. (FL), President, Pelorus EngineeringLast updated