For 1990-2009 cars

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 |

1. Disconnect the automatic temperature controller (ATC) connectors A and B.
2. Disconnect the connectors from the power transistor.
3. Measure the resistance circuit GRY/BLK from terminal 4 of the power transistor to terminal B1 of the ATC controller.

Does the resistance equal the specified value?

0 ohms

Go to Step 2

Go to Step 6

2 | Measure the resistance in the circuit from terminal 1 of the power module control unit to terminal B12 of the ATC controller. Does the resistance equal the specified value? | 0 ohms | Go to Step 3 | Go to Step 6
3 |

1. Reconnect the wiring harness to the ATC controller and to the power module control unit.
2. Turn ON the ignition, with the engine OFF.
3. Measure the voltage from ground to terminal B12 of the ATC controller.
4. Cycle the fan speed controller manually from the lowest, speed 1, to the highest speed 5.

Do the voltages measured match the specified ranges?

Speed 1:8.3-9.3 V

Speed 2: 6.3-7.3 V

Speed 3: 3.9-4.9 V

Speed 4: 2.2-3.2 V

Speed 5: 0-0.5 V

Go to Step 4

Go to Step 5

4 | Replace the ATC controller. Refer to Heater and Air Conditioning Control Replacement . Is the repair complete? | -- | System OK | --
5 | Measure the resistance in circuit PNK between terminal 6 of the power transistor and the blower motor terminal 2. Does the resistance equal the specified value? | 0 ohms | Go to Step 7 | Go to Step 6
6 | Repair or replace the wiring harness for the circuit PNK. Is the repair complete? | -- | System OK | --
7 | Inspect the wiring harness of the motor and power supply.

• | Inspect the blower relay.

• | Inspect fuse EF6.

Is there any problem in the wiring, the relay, or the fuse?

--

Go to Step 9

Go to Step 8

8 | Replace the power transistor. Refer to Blower Motor Control Module Replacement . Is the repair complete? | -- | System OK | --
9 | Repair or replace the wiring harness, the relay, or the fuse as required. Is the repair complete? | -- | System OK | --