Do you hear any clicking sounds coming from behind the instrument panel ? Electrically controlled actuators move temp . blend doors and they wear out .Plastic gears etc..
Electronic Automatic Temperature Control System
The electronic automatic temperature control (EATC) system operation is determined by the settings on the EATC module. The EATC system automatically maintains a selected temperature for vehicle interior comfort, including capabilities to maintain separate temperature settings for the driver and front passenger. The electronic temperature control capabilities are achieved by splitting the air distribution system internally and utilizing 2 individually operated temperature blend doors. The EATC system is composed of the EATC module, automatic temperature control (ATC) solenoid and manifold, blower motor speed control, 4 vacuum control motors, 2 temperature blend door actuators, in-car temperature sensor, ambient air temperature sensor and solar amplifier (sunload sensor) to control the various functions. Do you know about DTC'S - diagnostic trouble codes ?
The electronic automatic temperature control (EATC) system must be diagnosed by first retrieving any DTCs, if present.
- An on-demand (hard fault) DTC indicates that the fault is currently present. An on-demand DTC suggests a wiring fault, disconnected connector or component failure.
- A continuous (intermittent) DTC alone (corresponding on-demand DTC is not present) indicates that the fault is an intermittent condition and may not be currently present. A continuous only DTC suggests a poor wiring connection, loose pin or terminal or intermittent component failure.
On-demand (hard fault) or continuous (intermittent fault) DTCs can be retrieved using a diagnostic tool. If using a diagnostic tool, refer to the diagnostic tool operating manual.
On-demand DTCs can also be retrieved by carrying out the Electronic Automatic Temperature Control Module On-Demand Self Test. To retrieve and/or clear continuous DTCs carry out the Electronic Automatic Temperature Control Module - Retrieve Continuous DTCs procedure. Always carry out the Electronic Automatic Temperature Control Module On-Demand Self Test before retrieving continuous DTCs.
If no DTCs are present, GO to Symptom Chart for the appropriate diagnostic action.
EATC DTC Displayed
Action to Take
LH Blend Door Failure or Short
Go To Pinpoint Test A .
RH Blend Door Failure or Short
Go To Pinpoint Test A .
- The dual temperature control is inoperative/does not operate correctly - Dual Zone EATC
- Temperature blend door/actuator broken/binding
- EATC module
- CHECK the temperature blend doors/actuators for a binding or broken condition. If no condition is found, INSTALL a new EATC module. REFER to Section 412-01 . TEST the system for normal