Power Relay (P/No. 9900262013)
Check Point 1: Circuit Connection and Coil Resistance
Verify the connection at CN12 on the Control PCB (PWB ASSY).
Measure the coil resistance across the relay terminals.
Expected Resistance: Approximately 120 Ω
If the coil is open (∞ Ω) or 0 Ω, replace the Power Relay.
Check Point 2: Relay Operation During Normal Conditions
If relay does not operate (OPEN between COM and ON):
Confirm coil resistance = 120 Ω (approx.).
Measure DC +12 V at CN12 (Control PCB).
If no voltage is present → replace Control PCB.
If voltage is correct but relay still not operating → replace Power Relay.
If relay does not release (always ON even when all indoor units are stopped):
Exclude normal preheat operation.
Disconnect the connector from relay and check continuity between COM–ON.
If continuity exists while inactive → relay contacts stuck (welded) → replace Power Relay.
Diode Power Bridge (P/No. 0100122039)
Check Point 1: Circuit Connection
Confirm correct terminal wiring between ACTPM module and the diode bridge:
BLACK (In/Out) and WHITE (In/Out) connections to outdoor fan circuit.
Check Point 2: Open / Short Circuit Test
Remove each terminal from the bridge rectifier.
Measure resistance between the following pairs:
| Read Wire | Reference Terminal | Expected Resistance |
|---|---|---|
| BLACK (Out −) | WHITE (In +) | ≥ 1 MΩ |
| BLACK (In +) | WHITE (In −) | ≥ 1 MΩ |
| BLACK (In −) | WHITE (Out +) | ≥ 1 MΩ |
| WHITE (Out +) | WHITE (In −) | ≥ 1 MΩ |
⚠ If any reading shows low resistance (short circuit) or open circuit, replace the Diode Power Bridge.
Summary Table
| Component | Check | Normal Reading | Action if Abnormal |
|---|---|---|---|
| Power Relay Coil | CN12 | 120 Ω | Replace Power Relay |
| Relay Operation | COM–ON | Opens/closes properly | Replace Relay or Control PCB |
| Diode Bridge | All terminal pairs | ≥ 1 MΩ | Replace Diode Bridge |
