Heat pumps · Error codes · Midea
L9Midea
L9 on a Midea heat pump: Actual compressor frequency differs from target frequency by more than 15 Hz protection
Short answer
On a Midea heat pump, L9 means: Actual compressor frequency differs from target frequency by more than 15 Hz protection. The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 2 sources
What it means
The manual says: Actual compressor frequency differs from target frequency by more than 15 Hz protection.
Likely causes:
- Inverter module / compressor drive fault - follow inverter module troubleshooting (power supply, compressor windings U-V-W, inverter board, wiring).
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
What you can check
- Read and note the exact code shown on the controller display.
- Check the heat pump's breaker/isolator at the consumer unit is on.
- Restart once via the controller (OFF then ON) as the manual allows; if the code returns, call an engineer.
What the engineer will check
- Inverter module / compressor drive fault - follow inverter module troubleshooting (power supply, compressor windings U-V-W, inverter board, wiring).
Sources
- Midea M thermal Arctic Mono (4~16kW) Service Manual ↗ · not stated (MBT Confidential) · page 65 (table); inverter module troubleshooting section · Reviewed 23 September 2026
- M-Thermal A Series Split R32 Service Manual (Midea CAC, 202004) ↗ · 202004 (file v31) · page 51 (table); inverter module troubleshooting section · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026