Compressor Lock or Startup Failure

What it means

This code appears on Daikin split, ducted and cassette air conditioners and means the board tried to start the compressor but it did not turn properly or was detected as locked. After several attempts the unit stops trying to protect the compressor and the board. The same code can mean something else on other brands.

Models covered: Daikin split air conditioners and Daikin ducted/cassette (SkyAir) units, which share the same error code system; the code shows on the wired remote or via the wireless remote check function.

Related codes: H6L5E5H0

Symptoms4

• The outdoor unit tries to start, then stops and E6 appears.
• A hum or click from the compressor without it running.
• The outdoor fan may run while the compressor stays off.
• No cooling at all.

Possible causes5

• Loose, burnt or wrongly ordered compressor wiring after a repair.
• Low supply voltage at startup.
• Unequalized pressures at startup, such as restarting right after the unit stopped.
• Mechanical seizure inside the compressor from poor lubrication or age.
• A faulty power module (IPM) or outdoor PCB.

How to diagnose5

1. Switch the unit off at the breaker for at least ten minutes, then restart.
2. Check that the supply voltage is steady and does not sag at startup.
3. A technician checks the compressor wiring and terminals after discharging the inverter board.
4. The technician measures compressor winding resistance and insulation against Daikin specifications.
5. The technician tests the board output and power module per the service manual, using an inverter output checker where available.

How to fix5

1. Restart after waiting long enough for pressures to equalize.
2. Fix the voltage problem or fit a suitable voltage protector.
3. Repair the compressor wiring and restore the correct order per the wiring diagram.
4. Replace the outdoor PCB if its output is proven faulty.
5. Replace the compressor if it is mechanically seized, then evacuate, recharge and test the unit.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

Wiring and voltage fixes are cheap, the outdoor board is moderate to expensive, and an inverter compressor replacement is the top of the range.

Prices are rough estimates including the part and the technician’s fee, and vary with brand, model and part source.
Prices last updated: September 2026

Frequently asked questions