ACiQ EH03 Error Code

What does ACiQ EH03 mean?

EH03 means the indoor unit fan speed is out of control. When the indoor fan speed stays too low or too high for a certain time, the controller flags the failure code and the unit stops. The control system expects the fan motor to run within an acceptable speed band, and a sustained deviation triggers EH03.

Symptoms

• EH03 shown on the indoor unit display
• Indoor fan not spinning, spinning weakly, or running erratically
• Reduced or no airflow from the indoor unit
• Unit shuts off after the fault is detected

Common causes

• Obstructed or seized indoor fan that will not turn freely
• Loose or damaged fan motor wiring
• Faulty indoor fan motor
• Faulty indoor PCB fan-drive output

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Diagnostic steps

1. Power cycle the unit

   Power off, wait about two minutes, then restart and see if the problem remains.

2. Check the fan turns freely

   With power off, rotate the indoor fan by hand; if it does not turn easily, find and resolve the obstruction.

3. Inspect the fan wiring

   Confirm the fan motor is properly wired and the connections are secure.

4. Test the motor drive voltage

   Measure the voltage supplied to the fan motor from the PCB; if it is out of range, the board is suspect.

5. Replace the failed component

   Replace the main PCB if its output is abnormal, otherwise replace the fan motor.

When to call a professional

Diagnosing EH03 means measuring drive voltages at the fan motor connector and potentially replacing the indoor fan motor or control board. If clearing an obvious obstruction and reseating wiring does not resolve it, contact a licensed HVAC technician. Electrical measurement and component replacement inside the indoor unit, where capacitors can retain charge, should be performed only by a qualified professional.