*REAR A/C HEATER BLEND DOOR INOPERABLE

For a complete wiring diagram Refer to Section 8W.

Possible Causes

(F850) FUSED RUN RELAY OUTPUT CIRCUIT OPEN OR SHORTED

(Z908) GROUND CIRCUIT OPEN

(C54) REAR BLEND DOOR CONTROL CIRCUIT OPEN OR SHORTED

REAR BLEND DOOR ACTUATOR

REAR A/C HEATER CONTROL

Diagnostic Test

1.VERIFY SYMPTOM

Did the air change temperature (hot, mid-level, and cold)?

Yes

The rear blend door actuator is working properly. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals. Repair as necessary.

Go To 2

2.CHECK JB FUSE #5 (F850) FUSED RUN RELAY OUTPUT CIRCUIT

Does the test light illuminate brightly on both sides of the fuse?

Yes

Go To 3

No - Open Fuse

Using the Wiring Diagram as a guide, repair the (F850) Fused Run Relay Output circuit for a short to ground. Replace the fuse.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

No - No Power to Fuse

Using the Wiring Diagram as a guide, repair the (F850) Fused Run Relay Output circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

3.CHECK THE (F850) FUSED RUN RELAY OUTPUT CIRCUIT FOR AN OPEN AT THE REAR A/C HEATER CONTROL

Is the voltage above 10 volts?

Yes

Go To 4

Repair the (F850) Fused Run Relay output circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

4.CHECK THE (Z908) GROUND CIRCUIT FOR AN OPEN AT THE REAR A/C HEATER CONTROL

Is the resistance below 5.0 ohms?

Yes

Go To 5

Repair the (Z908) Ground circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

5.CHECK THE (F850) FUSED RUN RELAY OUTPUT CIRCUIT FOR AN OPEN AT THE REAR BLEND DOOR ACTUATOR

Is the voltage above 10 volts?

Yes

Go To 6

Repair the (F850) Fused Run Relay output circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

6.CHECK THE (Z908) GROUND CIRCUIT FOR AN OPEN AT THE REAR BLEND DOOR ACTUATOR

Is the resistance below 5.0 ohms?

Yes

Go To 7

Repair the (Z908) Ground circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

7.CHECK THE (C54) REAR BLEND DOOR CONTROL CIRCUIT FUNCTION

Below 0.5 Volts @ Hot
2.0 Volts ± 0.5 Volts @ Mid-Level
Within 0.5 Volts of Battery Voltage @ Cold

Is the voltage within specifications?

Yes

Remove the Blend Door actuator from the A/C Heater Housing Assembly. By hand, attempt to rotate the actuator in both directions. Inspect the A/C Heater Housing for damage, and for a broken or binding door. Repair as necessary in accordance with the Service Information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

No – Voltage Remains Above 10 Volts

Go To 8

No – Voltage Remains Below 2 Volts

Go To 9

8.CHECK THE (C54) REAR BLEND DOOR CONTROL CIRCUIT FOR A SHORT TO THE (F850) FUSED RUN RELAY OUTPUT CIRCUIT AT THE REAR BLEND DOOR ACTUATOR

Is the resistance below 10k ohms?

Yes

Repair the (C54) Rear Blend Door Control circuit for a short to the (F850) Fused Run Relay Output circuit.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Replace the Rear A/C Heater Control in accordance with the Service Information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

9.CHECK THE (C54) REAR BLEND DOOR CONTROL CIRCUIT FOR A SHORT TO THE (Z908) GROUND CIRCUIT AT THE REAR BLEND DOOR ACTUATOR

Is the resistance below 10k ohms?

Yes

Repair the (C54) Rear Blend Door Control circuit for a short to the (Z908) Ground circuit.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Go To 10

10.CHECK THE (C54) REAR BLEND DOOR CONTROL CIRCUIT FOR AN OPEN BETWEEN THE REAR BLEND DOOR ACTUATOR HARNESS CONNECTOR AND THE REAR A/C HEATER CONTROL HARNESS CONNECTOR

Is the resistance below 5.0 ohms?

Yes

Replace the Rear A/C Heater Control in accordance with the Service Information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Repair the (C54) Rear Blend Door Control circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).