What happens
Leakage across the valve's internal paths reduces useful system pressure separation and capacity.
Typical symptoms
Weak heating or cooling despite a running compressor and plausible charge.
Checks that distinguish this cause
Compare temperatures and pressures at the specific valve paths using the manufacturer's method after verifying mode, airflow and charge.
What can look similar
Poor compressor pumping can create a similar weak-capacity complaint.
Repair direction
Replace a confirmed leaking reversing valve using the approved procedure.
Verify the repair
Verify mode-specific temperatures and system performance after repair.
Equipment-specific limits
Electrical command does not prove the main valve shifted. O/B energization depends on the system design, and some conditions are normal during defrost.
Practice this diagnosis
These simulated calls exercise this component or repair family. The article describes a broader diagnostic process; a call may represent a different cause within that family.
References and applicability
Original HVACSim explanations with manufacturer and instrument-maker references for further reading. These resources support the subject; their model-specific examples are not specifications for every system.
- Resideo: RTH6360 thermostat installation and setupExamples of heat-pump O/B and staging setup. Menu numbers vary by thermostat.
- Copeland: CoreSense diagnostics for scroll air-conditioning compressors (AE8-1379)Model-specific diagnostic examples; flash codes are not universal.
Editorial review: 2026-09-29. Verify the current manual for the installed model.