Honda Accord: A/C Signal Circuit Troubleshooting - Heating/Air Conditioning - Heating, Ventilation, and Air Conditioning - Honda Accord MK8 2008-2012 Service ManualHonda Accord: A/C Signal Circuit Troubleshooting

NOTE: • If the blower motor does not run at all speeds, the A/C compressor will be inoperative. Run the self-diagnostic function, and check for DTC 12. Before performing any other troubleshooting, repair the cause of the inoperative blower motor.

• Do not use this troubleshooting procedure if any of the following items are operative: The condenser fan, the radiator fan, or the A/C compressor, or if the heater is inoperative. Refer to the symptom troubleshooting index.

• Before doing symptom troubleshooting, check for powertrain DTCs (see page 11-3).AIso check for B-CAN codes.

1. Turn the ignition switch to ON (II).

2. Chek if the blower motor operates at all speede.

Does the blower motor operate at all speeds? YES

-Go to step 3.

NO

-Repair the problem in the blower motor circuit (see page21-38).

3. Turn the ignition switch to LOCK (0).

4. Disconnect the HVAC control unit 24P connector.

5. Turn the ignition switch to ON (II).

6. Measure the voltage between HVAC control unit 24P connector terminal No. 21 and body ground.

HVAC CONTROL UNIT 24P CONNECTOR

Wire side of female terminals


Wire side of female terminals

Is there battery voltage? YES

-Go to step 8.

NO

-Go to step 7.

7. Measure the voltage between driver's under-dash fuse/relay box connector F (33P) terminal No. 5 and body ground.

DRIVER'S UNDER-DASH FUSE/RELAY BOX CONNECTOR F (33P)

Wire side of female terminals


Wire side of female terminals

Is there battery voltage? YES

-Repair an open in the wire between the HVAC control unit and the MICU.

NO-

Check for loose wire or poor connections at driver's under-dash fuse/relay box connector F (33P) terminal No. 5. If the connections are good, substitute a known-good MICU and recheck. If the symptom goes away, replace the original MlCU.

8. Turn the ignition switch to LOCK (0).

9. Measure the evaporator temperature sensor resistance between HVAC control unit 24P connector terminals No. 14 and No. 15.

HVAC CONTROL UNIT 24P CONNECTOR

Wire side of female terminals


Wire side of female terminals

Is resistance less than 24 kO? YES

-Check for loose wires or poor connections at the HVAC control unit 24P connector. If the connections are good, substitute a known-good HVAC control unit and recheck. If the symptom goes away, replace the original HVAC control unit.

NO

-Test the evaporator temperature sensor (see page21-58).

    A/C Pressure Switch Circuit Troubleshooting
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    Evaporator Temperature Sensor Test
    NOTE: Before testing the sensor, check for HVAC DTCs (see page 2 1 - 9). 1. Remove the evaporator temperature sensor (see page 21-67). 2. Dip the sensor in ice water, and measure the resistan ...

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