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

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0) and then back 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 in 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 AIR MIX 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.
36P: 7P:

No. 1 No. 7

No. 27 No. 6

No. 28 No. 5

No. 29 No. 4

No. 30 No. 3

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

Is there continuity?

YES -Go to step 10.

NO -Repair an open in the wires between the climate control unit and the mode control motor.
Check for continuity between body ground and climate control unit 36P connector terminals No. 27, No. 28, No. 29, and No. 30 individually.

Fig 2: Checking Continuity Between Body Ground And Climate Control Unit 36P Connector Terminals No. 27, 28, 29 And 30
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to body ground in the wires 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.

From terminal	To terminals
27	28, 29, 30
28	29, 30
29	30

Fig 3: Identifying Climate Control Unit 36P Connector Terminals

Courtesy of AMERICAN HONDA MOTOR CO., INC.

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).
Measure the voltage between body ground and climate control unit 36P connector terminals No. 27, No. 28, No. 29, and No. 30 individually.

Fig 4: Measuring Voltage Between Body Ground And Climate Control Unit 36P Connector Terminals No. 27, 28, 29 And 30
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there any voltage?

YES -Repair a short to power in the wires 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 ).