Indoor unit displays H4; unit may not start or may shut down quickly.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Shorted compressor, Shorted IPM module on outdoor PCB, Power surge damage, Poor grounding of outdoor unit

Safety first: This is a high‑voltage electronics fault. Do not attempt board‑level repairs yourself.

Step 1 – Power reset: Turn OFF the breaker for 10–15 minutes, then restore power and test once. If H4 reappears, leave the unit OFF.
Step 2 – Visual inspection: With power OFF, open the outdoor electrical panel and look for burnt components or smells on the PCB.
Step 3 – Call a technician: A professional should test compressor windings and the IPM module, and replace the outdoor PCB and/or compressor as needed.

Professional Required 5/5

Outdoor Inverter PCB

Check Price on Amazon

We may earn a commission from links on this page.