DTC 01

CIRCUIT DESCRIPTION

The temperature air valve actuator motor is driven by the control assembly microprocessor (15) to operate the temperature air valve. The position of the temperature air valve is adjusted to maintain the requested interior temperature. A feedback potentiometer is used in the motor so that the microprocessor (15) will know the position of the temperature air valve. The feedback potentiometer is part of a fiat pack design motor which is mounted on the rear-facing surface of the air conditioning module. A low voltage represents a hot air valve position and a high voltage a cold air valve position. If Code 02 had been set, the microprocessor (15) will enter a default value of 128 counts so the driver may still control full hot and full cold.

TEST DESCRIPTION

The following numbers refer to circled numbers on the diagnostic charts.

Code 01 or 02 indicates the microprocessor has seen an open or short in the potentiometer circuit, or actuator and air valve will not go to hot or cold position when microprocessor (15) commands it, causing microprocessor (15) to see high or low voltage feedback from potentiometer, which sets code.

1. If temperature will not vary manually, full hot or cold, the actuator motor is not functioning. Refer to Step 6.

2. If a new blower motor was installed or the temperature air valve was disturbed. the microprocessor (15) will have to be recalibrated due to previous measured position and new position tripping Code 01 or 02.

3. This test will determine if other malfunctions are causing a loss of cooling or heating. No code 01 or 02 will set if other systems are causing the loss. Refer to appropriate section if no code 01 or 02 is stored.

4. This test will determine if a short to power or open is present at the motor connector. A short to power will damage the microprocessor (15). requiring repair of short and replacement of microprocessor (15).

5. This test will determine if a short to power, open or ground is present in motor feedback potentiometer circuits. The potentiometer is part of the motor

6. This step will determine if actuator motor circuits 1199 and 1236 are open or one circuit is shorted so door will not move.

7. This test will determine if a short to power is present in the motor feedback potentiometer circuit.

8. This test will determine if an open is present in the motor feedback potentiometer ground circuit.

9. This test will determine if 12 volts are present to the microprocessor (15). Lack of voltage may cause low or no amperage to motor, setting Code 02.

DIAGNOSTIC AIDS

If counts are high and full hot is coming from outlets or counts are low and cooled air is entering vehicle, check for binding temperature air valve while replacing actuator motor.

A "scan" type tool or parameter -34 (temperature air valve feedback) may be monitored for large count changes but should be monitored by slowly increasing the temperature since the microprocessor (15) will not update for 200 msec. Look for flat spots (open; low counts). Replace potentiometer if open/large count drop in small movement is found.