HVAC Control Motor Power Supply Circuit Troubleshooting

Is the fuse OK? 

YES  -Go to step 2.

NO  -Replace the fuse, and recheck. If the fuse blows again, check for a short in the No. 9 (7.5 A) fuse circuit.

Is the relay OK? 

YES  -With the control motor relay disconnected, go to step 3.

NO  -Replace the control motor relay.

Fig 1: Measuring Voltage Between Body Ground And Control Motor Relay 4P Connector Terminals No. 1 And No. 4

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage? 

YES  -Go to step 4.

NO  -Repair an open in the wire(s) between the No. 9 (7.5 A) fuse in the passenger's under-dash fuse/relay box and the control motor relay.

40P: 4P:

No. 5 No. 2

No. 39 No. 3

Fig 2: Checking Continuity Between Following Terminals Of Climate Control Unit 40P Connector And Control Motor Relay 4P Connector

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity? 

YES  -Check for loose wires or poor connections at the climate control unit 40P connector and at the control motor relay. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit (see HEATER VALVE CABLE ADJUSTMENT  ).

NO  -Repair an open in the wire(s) between the control motor relay and the climate control unit.