There are two sources of air available to the air distribution system:
Recirculated air is used when the electronic manual temperature control (EMTC) mode selector is set in MAX A/C or OFF, or if the RECIRC button is selected in any mode except DEFROST. If the vehicle is equipped with electronic automatic temperature control (EATC), recirculated air is used in OFF, and is available in all modes except DEFROST.
Air distribution within the vehicle is determined by the EMTC mode selections, or is controlled by the EATC system in the AUTO mode. The air distribution mode on EATC vehicles may be overridden by the driver if desired. Three airflow mode doors are used to direct airflow within the heater core and evaporator core housing and the plenum chamber (18471).
**********Vehicles equipped with dual-zone EMTC and EATC systems use a partitioned plenum chamber, and heater core and evaporator core housing assembly with two separate temperature blend doors. This allows for individual temperature settings to be selected for the RH and LH air outlets. The airflow mode doors are similar for EMTC and EATC systems, therefore the airflow mode for the RH and LH outlets will remain similar in all modes, regardless of the temperature(s) selected.**********
Air enters the passenger compartment from the:
instrument panel A/C registers.
Heater outlet floor ducts.
Windshield defroster duct.
Side window demisters.
Passenger compartment air is exhausted from the vehicle through open windows or body air vents.
Pinpoint Test J: DTC B2266 or B2267: Temperature Blend Door Open/Short to Ground/Temperature Control Is Inoperative/Does Not Operate Correctly
Under normal operation, to rotate the blend door actuator clockwise, the EMTC module or EATC module supplies voltage to the Blend door actuator motors through the door actuator feed A circuits, and supplies ground through the door actuator feed B circuits. To rotate the blend door actuator counterclockwise, the EMTC module or EATC module reverses the voltage and ground circuits.
The blend door actuator feedback resistors are supplied a ground from the EMTC module or EATC module by the blend door actuator return circuits and a 5-volt reference voltage on the blend door actuator reference circuits. The EMTC module or EATC module reads the voltage on the blend door actuator feedback circuits to determine the blend door actuator position by the position of the actuator feedback resistor wiper arm.
Door actuator feed A circuits
LH Blend - 245 (BN/LG)
RH Blend - 1069 (OG/LB)
Door actuator feed B circuits
LH Blend - 246 (VT)
RH Blend - 660 (YE/LG)
Door actuator return circuits
LH Blend - 438 (RD/WH)
RH Blend - 438 (RD/WH)
Door actuator reference circuits
LH Blend - 436 (RD/LG)
RH Blend - 436 (RD/LG)
Door actuator feedback circuits
LH Blend - 437 (YE/LG)
RH Blend - 435 (YE/LB)
An open, short to voltage, ground or together in door actuator open, close, return, reference or feedback circuits.
Blend door actuator motor.
Stuck or bound linkage or door.
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Tuesday, January 27th, 2009 AT 8:44 PM