Air Delivery Improper - Auxiliary. GMC Truck Envoy

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2002 🢒 Envoy - 2WD 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Air Delivery Improper - Auxiliary

Air Delivery Improper - Auxiliary Body Type VIN 3

Diagnostic Aids

•	When the primary HVAC system is placed to the defrost position, the auxiliary HVAC controls are disabled.

•	The auxiliary blower motor is only enabled when in medium and high speeds. When low speed is selected the primary HVAC blower forces air through the auxiliary system. The air speed will vary depending on the speed of the primary blower motor.

Step

Action

Value(s)

Yes

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: Air does not flow correctly from the auxiliary air distribution outlets.

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

Turn ON the ignition, with the engine OFF.
Turn OFF the auxiliary HVAC control module.

Is the auxiliary blower motor OFF?

Go to Step 3

Go to Auxiliary Blower Motor Always On

Place the front mode switch in the bi-level position.
Place the front blower motor switch in the minimum speed position.
Place the auxiliary blower motor switch in the medium speed position and the maximum speed position.

Does the auxiliary blower motor operate in both speed positions?

Go to Auxiliary Blower Motor Inoperative

Go to Step 4

Does the auxiliary blower motor operate in each speed position?

Go to Step 5

Go to Auxiliary Blower Motor Malfunction

With a scan tool, observe the Mode Switch parameter in the Rear Seat Audio data list.
Activate the mode switch.

Does the scan tool indicate that the Mode Switch parameter changes state?

Go to Step 6

Go to Step 12

Turn OFF the ignition.
Disconnect the auxiliary mode actuator.
Turn ON the ignition, with the engine OFF.
Probe the ignition 3 voltage circuit of the auxiliary mode actuator with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 13

Test the ground circuit of the auxiliary mode actuator for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 8

Measure the voltage from the auxiliary mode door control circuit of the auxiliary mode actuator to a good ground.
Place the auxiliary mode switch in each position.

Does the voltage measure near the specified values?

•	FLOOR: 3-5 V

•	BI-LEVEL: 7-9 V

•	PANEL: 11-13 V

Go to Step 10

Go to Step 9

Test the auxiliary mode door control circuit of the auxiliary mode actuator for an open, a short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 12

Inspect the auxiliary mode door and the auxiliary mode actuator for the following:

•	Misaligned auxiliary mode actuator.

•	Broken or binding linkages or auxiliary mode door.

•	Obstruction that prevents the recirculation actuator from operating within its full range of motion.

•	Missing seals to the auxiliary mode door

•	Misaligned seals to the auxiliary mode door

Did you find and correct the condition?

Go to Step 16

Go to Step 11

Inspect for poor connections at the harness connector of the auxiliary mode actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 14

Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 15

Repair the ignition 3 voltage circuit of the auxiliary mode actuator. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

Replace the auxiliary mode actuator. Refer to Mode Actuator Replacement - Console .

Did you complete the replacement?

Go to Step 16

Replace the auxiliary HVAC control module. Refer to Auxiliary Heater and Air Conditioning Control Module Replacement .

Did you complete the replacement?

Go to Step 16

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3

Air Delivery Improper - Auxiliary Body Type VIN 6

Step	Action	Yes	No
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The auxiliary mode doors cannot be adjusted.
1	Did you perform the HVAC Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - HVAC Systems - Automatic
2	Recalibrate actuators. Refer to Actuator Recalibration . Turn ON the ignition, with the engine OFF. With a scan tool, observe the DTC list in Rear HVAC/RSA. Does the scan tool display DTC B0145, B0428, or B3531?	Go to Diagnostic Trouble Code (DTC) List	Go to Step 3
3	Turn ON the ignition, with the engine OFF. Place the front auxiliary blower motor switch in each speed position. Does the front auxiliary blower motor operate in any of the speed positions?	Go to Step 4	Go to Auxiliary Blower Motor Inoperative
4	Does the auxiliary blower motor operate at the desired speed?	Go to Step 5	Go to Auxiliary Blower Motor Malfunction
5	Turn ON the ignition, with the engine OFF. Place the front auxiliary blower motor switch in the Rear position. With a scan tool, observe the Console Mode Door actual and the Mode Door Actual parameter in the Rear HVAC/RSA data list. Place the auxiliary mode switch from the floor position to the upper outlets position. Does both the Console Mode Door and the Mode Door Actual parameters count value change?	Go to Step 8	Go to Step 6
6	Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 8	Go to Step 7
7	Replace the auxiliary HVAC control module. Refer to Auxiliary Heater and Air Conditioning Control Module Replacement . Did you complete the replacement?	Go to Step 8	--
8	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2