Test I: Incorrect/Erratic Direction of Airflow From Outlets - EATC

PINPOINT TEST I: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S) - EATC

I1-I3:

I4-I6:

I7-I9:

I9-I11:

I11-I14:

I14-I16:

I16-I17:

I18-I20:

Normal Operation
Under normal operation, the automatic temperature control (ATC) solenoid and manifold receives a ground from the electronic automatic temperature control (EATC) module through circuit RH226 (WH/VT). Depending on which solenoid is to be energized, the ATC solenoid and manifold receives voltage from the EATC module through circuits:
- CH220 (GN/BN) for the air inlet door vacuum control motor.
- CH221 (GY/VT) for the defrost door vacuum control motor.
- CH222 (WH/VT) for the floor door vacuum control motor.
- CH223 (YE/BU) for the panel door vacuum control motor.
- CH224 (BU/OG) for the heater control valve.

Engine vacuum is supplied to the ATC solenoid and manifold. When one of the solenoids is energized, vacuum is applied to the control motor or valve and the desired door or valve is either opened or closed.

Possible Causes
- An open, short to voltage, ground or together in circuits CH220 (GN/BN), CH221 (GY/VT), CH222 (WH/VT), CH223 (YE/BU) or CH224 (BU/OG)
- ATC solenoid and manifold
- EATC module
- Heater control valve
- Vacuum control motor
- Stuck or bound linkage or door
- Leaking or plugged vacuum hose