H39 — Abnormal indoor operating unit or standby units

What does H39 mean?

The indoor unit or standby units have operated abnormally three times within 40 minutes. This indicates a potential issue with wiring, piping, the expansion valve, or the indoor heat exchanger sensor.

• Incorrect wiring or connection
• Expansion valve abnormality
• Indoor heat exchanger sensor open circuit

Click steps to track your progress.

1. 1

   Check the indoor/outdoor connection wires and pipes.

2. 2

   Inspect the indoor heat exchanger sensor's lead wire and connector.

3. 3

   Examine the expansion valve and its lead wire and connector.