Safety first: Turn OFF power at the outdoor disconnect before accessing the outdoor unit.

Step 1 – Listen for valve change: When switching between COOL and HEAT, listen at the outdoor unit for a distinct whooshing sound indicating the reversing valve is shifting. Absence of this sound may indicate a stuck valve or no coil energization.
Step 2 – Inspect coil wiring: Locate the reversing valve solenoid coil on the outdoor unit. Check that its wires are firmly connected and not damaged.
Step 3 – Coil resistance check (pro): Using a multimeter, measure the coil resistance and compare with Klimaire specifications. Replace the coil if open or shorted.
Step 4 – PCB output check (pro): A technician should verify that the outdoor PCB is sending the correct voltage to the coil when changing modes.
Step 5 – Valve replacement (pro only): If the coil and PCB are good but the valve is stuck internally, the reversing valve must be replaced by a licensed HVAC technician, as this requires refrigerant recovery and brazing.

Indoor unit shows E7 and the system may not switch between cooling and heating properly.

Possible Causes