General Assist Technical Reference
Indoor Fan Motor Resistance Testing
Wall-mounted indoor units - AS7-14 and AS18-24
Electrical integrity check using fan motor winding resistance at 20°C
This procedure is used to verify the electrical integrity of fan motors in wall-mounted indoor units by measuring winding resistance at 20°C.
Safety: Isolate power to the indoor unit before disconnecting the fan motor or carrying out resistance measurements. Confirm the circuit is de-energised before testing.
1. Check Point 1 - Models AS7-14
Part No.: 9601172017
Read Wire / Resistance Values (±8%)
| Measurement | Resistance (Ω) |
|---|---|
| Black - Yellow | 138 |
| White - Yellow | 136 |
Notes:
- Includes a thermal protector (136°C).
- If the resistance is open, shorted, or outside the tolerance range, replace the fan motor.
2. Check Point 2 - Models AS18-24
Part No.: 9601388012
Read Wire / Resistance Values (±8%)
| Measurement | Resistance (Ω) |
|---|---|
| Red - White | 129 |
| Black - Blue | 21 |
| Blue - Red | 277 |
Notes:
- Equipped with a thermal protector (140°C) for overheat protection.
- Resistance readings may vary slightly depending on ambient temperature.
3. Diagnostic Notes
- Always perform resistance testing at room temperature (20°C).
- If abnormal readings are detected, first confirm no obstruction or foreign matter is impeding fan rotation.
- Ensure the thermal protector is operational before declaring a motor fault.
- Replace the motor if readings fall significantly outside the specified tolerance or the protector is open-circuit.
Diagnostic outcome: A fan motor with an open circuit, short circuit, resistance outside the specified ±8% tolerance, or an open thermal protector should be replaced.
