Goodman
RV / no shift
LockoutReversing valve / no shift
Unit runs the opposite mode, or pressures never swap when O/B is commanded.
Walk RV / no shift in Diagnose
Sign in for the next measurement
First check
1 Confirm O/B is energized the way THIS outdoor expects
Most US splits energize O in cool. Some Rheem/Ruud energize B in heat. Read the Goodman GSZC18 diagram, not a generic heat-pump card. Voltage at the RV solenoid during the call that should energize it. Confirm O vs B on THIS outdoor diagram — do not assume Carrier O-on-cool.
Expect: Correct 24 V at the solenoid for the mode that is failing.
The rest of the walkthrough is Diagnose.
On the plates
- Voltage at the RV solenoid during the call that should energize it. Confirm O vs B on THIS outdoor diagram — do not assume Carrier O-on-cool.
- Solenoid ohms / mechanical valve stuck. Tap test is not a repair.
- Suction line temp and gauge swap are the prove. Indoor blowing cool on a heat call with the outdoor running is RV or O/B until proven otherwise.