DTC B1239 or DTC indicator D and A/C: An Open or Short in the Mode Control Motor Circuit

Clear the DTC with the HDS.
Turn the ignition switch to LOCK (0), and then to ON (II).
Do the Self-Diagnostic Function with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS ) or the climate control unit (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS ).
Check for DTCs.
Is DTC B1239 or D and A/C indicated?

YES -Go to step 5.

NO -Intermittent failure. Check for loose wires or poor connections on the mode control motor circuit.
Turn the ignition switch to LOCK (0).
Test the mode control motor (see MODE CONTROL MOTOR TEST ).
Is the mode control motor OK?

YES -Go to step 7.

NO -Replace the mode control motor (see MODE CONTROL MOTOR REPLACEMENT ).
Disconnect the mode control motor 7P connector.
Disconnect the climate control unit 36P connector.
Check for continuity between the following terminals of the climate control unit 36P connector and the mode control motor 7P connector.
7P: 36P:

No. 1 No. 12

No. 2 No. 1

No. 3 No. 2

No. 4 No. 3

No. 5 No. 4

Fig 1: Checking Continuity Between Climate Control Unit 36P Connector Terminals And Mode Control Motor 7P Connector Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 10.

NO -Repair an open in the wire(s) between the climate control unit and the mode control motor.
Check for continuity between body ground and climate control unit 36P connector terminals No. 1, 2, 3, and No. 4 individually.

Fig 2: Checking Continuity Between Body Ground And Climate Control Unit 36P Connector Terminals No. 1, 2, 3, And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to body ground in the wire(s) between the climate control unit and the mode control motor.

NO -Go to step 11.

Check for continuity between the climate control unit 36P connector terminals as follows.

36P CONNECTOR TERMINALS REFERENCE

From terminal	To terminals
1	2, 3, 4
2	3, 4
3	4

Is there continuity between any of the terminals?

YES -Repair a short in the wires.

NO -Go to step 12.

Turn the ignition switch to ON (II), and check the same terminals for voltage to body ground.

Fig 3: Checking Voltage Between Body Ground And Climate Control Unit 36P Connector Terminals No. 1, 2, 3, And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there any voltage?

YES -Repair a short to power in the wire(s) between the climate control unit and the mode control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit.

NO -Check for loose wires or poor connections at the climate control unit 36P connector and at the mode control motor 7P connector. 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 CLIMATE CONTROL UNIT REMOVAL/INSTALLATION ).