Unit displays H4 and stops; may restart after power cycle then fail again
Safety Warning
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
How to Fix / Troubleshooting
Safety first: High-voltage DC is present on inverter boards. Do not touch components with power applied. Turn off breaker and wait several minutes for capacitors to discharge.
Steps to check (visual only):
- 1. Inspect outdoor PCB: Look for burn marks, cracked components, or bulging capacitors on the inverter board.
- 2. Check heatsink and fan: Ensure the inverter heatsink is not clogged with dust and that any PCB cooling fan (if present) is operational.
- 3. Tighten power terminals: With power OFF, gently tighten main power and compressor terminals.
When to call a technician: H4 requires professional diagnosis with proper tools. The inverter module or compressor may need replacement.
Repair Difficulty
Required Part
We may earn a commission from links on this page.