Pinpoint Test D: Incorrect/Erratic Direction Of Airflow From Outlet(s)

Climate Control System

Pinpoint Tests

Pinpoint Test D: Incorrect/Erratic Direction of Airflow From Outlet(s)

Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number

Normal Operation

Under normal operation, to rotate the mode door actuator clockwise, the HVAC module supplies voltage to the DEFROST and FLOOR/PANEL mode door actuator motors through the door actuator feed B circuits, and supplies ground through the door actuator feed A circuits. To rotate the mode door actuator counterclockwise, the HVAC module reverses the voltage and ground circuits.

The mode door actuator feedback resistors are supplied a ground from the HVAC module by the mode door actuator return circuits and a 5-volt reference voltage on the mode door actuator reference circuits. The HVAC module reads the voltage on the mode door actuator feedback circuits to determine the mode door actuator position by the position of the actuator feedback resistor wiper arm.

Door actuator feed B circuits
- Defrost - 1137 (YE/LG)
- Floor/Panel - 1129 (BN/WH)

Door actuator feed A circuits
- Defrost - 1136 (RD/WH)
- Floor/Panel - 1128 (GY/LB)

Door actuator return circuits
- Defrost - 438 (RD/WH)
- Floor/Panel - 438 (RD/WH)

Door actuator reference circuits
- Defrost - 436 (RD/LG)
- Floor/Panel - 436 (RD/LG)

Door actuator feedback circuits
- Defrost - 1982 (LB/BK)
- Floor/Panel - 435 (YE/LB)

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- HVAC module
- Stuck or bound linkage or door

PINPOINT TEST D: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET(S)

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D1 CHECK THE AIRFLOW

- Ignition ON.
- Check the airflow in the PANEL, DEFROST and FLOOR modes.
- Is the airflow correct in each setting?

Yes
The system is operating normally.

No
If the RECIRC button does not change the air inlet door position, Go To Pinpoint Test C. Pinpoint Test C: The Air Inlet Mode Door Is Inoperative

GO to D2.

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D2 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE

NOTICE: Use the correct size flex probe from the Flex Probe Kit for all test connections. The use of the correct size flex probe is critical to avoid damage to the connector terminals.

NOTE: Check all electrical connectors for proper seating before disconnecting. If incorrectly seated, reseat and lock the connector. Test the system operation. If the condition remains, continue with this test.

- Disconnect: HVAC Module C294a.
- Measure the resistance between HVAC module C294a-5, circuit 436 (RD/LG) and HVAC module C294a-15, circuit 438 (RD/WH).

- Is the resistance greater than 500 ohms?

Yes
If the airflow is from the floor only or panel only in any mode except OFF and DEFROST and airflow is from defrost only on DEFROST mode, follow diagnostics for floor/panel mode door actuator. GO to D3.

If the airflow is from the defrost only in all modes except OFF or from FLOOR/PANEL in DEFROST mode, follow diagnostics for defrost mode door actuator. GO to D3.

No
REPAIR circuits 436 (RD/LG) and 438 (RD/WH) for a short together. TEST the system for normal operation.

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D3 CHECK THE POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE

- Measure the low-side resistance between HVAC module C294a-15, circuit 438 (RD/WH) and the following:
- For floor/panel mode door actuator: HVAC module C294a-16, circuit 435 (YE/LB).
- For defrost mode door actuator: HVAC module C294a-17, circuit 1982 (LB/BK).

- Measure the high-side resistance between HVAC module C294a-5, circuit 436 (RD/LG) and the following:
- For floor/panel mode door actuator: HVAC module C294a-16, circuit 435 (YE/LB).
- For defrost mode door actuator: HVAC module C294a-17, circuit 1982 (LB/BK).

- Is the resistance between 225 and 11,275 ohms?

Yes
GO to D4.

No
CARRY OUT the Floor/Panel Mode Door Actuator or Defrost Mode Door Actuator Component Test. If the actuator tests OK and: Floor/Panel Mode Door Actuator

If the low-side resistance only is greater than 11,275 ohms, REPAIR circuit 438 (RD/WH) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

If the low-side resistance only is less than 225 ohms, REPAIR circuits (floor/panel) 435 (YE/LB) or (defrost) 1982 (LB/BK) and 438 (RD/WH) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

If the high-side resistance only is greater than 11,275 ohms, REPAIR circuit 436 (RD/LG) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

If thehigh-side resistance only is less than 225 ohms, REPAIR circuits (floor/panel) 435 (YE/LB) or (defrost) 1982 (LB/BK) and 436 (RD/LG) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

If thehigh-side and low-side resistance is greater than 11,275 ohms, REPAIR circuit (floor/panel) 435 (YE/LB) or (defrost) 1982 (LB/BK) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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D4 CHECK CIRCUITS 436 (RD/LG), 435 (YE/LB) OR 1982 (LB/BK) FOR A SHORT TO GROUND

- Measure the resistance between ground and the following:
- HVAC module C294a-5, circuit 436 (RD/LG).
- For floor/panel door actuator: HVAC module C294a-16, circuit 435 (YE/LB).
- For defrost door actuator: HVAC module C294a-17, circuit 1982 (LB/BK).

- Is the resistance greater than 10,000 ohms?

Yes
GO to D5.

No
REPAIR circuit(s) for a short to ground. TEST the system for normal operation.

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D5 CHECK CIRCUITS 438 (RD/WH), 435 (YE/LB) OR 1982 (LB/BK) FOR A SHORT TO POWER

- Ignition ON.
- Measure the voltage between ground and the following:
- HVAC module C294a-15, circuit 438 (RD/WH).
- For floor/panel door actuator: HVAC module C294a-16, circuit 435 (YE/LB).
- For defrost door actuator: HVAC module C294a-17, circuit 1982 (LB/BK).

- Is any voltage present?

Yes
REPAIR circuit(s) for a short to power. TEST the system for normal operation.

No
For floor/panel mode door actuator: GO to D6.

For defrost mode door actuator: GO to D7.

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D6 CHECK THE FLOOR/PANEL MODE DOOR ACTUATOR OPERATION

NOTE: If a jumper fuse opens while carrying out this test step, repair the circuit(s) for a short.

- Measure the low-side resistance between HVAC module C294a-15, circuit 438 (RD/WH) and HVAC module C294a-16, circuit 435 (YE/LB).

- For no more than 3 seconds, connect a fused jumper wire between:
- HVAC module C294a-26, circuit 1566 (RD/YE) and HVAC module C294a-20, circuit 1129 (BN/WH).
- HVAC module C294a-1, circuit 1205 (BK) and HVAC module C294a-19, circuit 1128 (GY/LB).

- Remove the fused jumpers.
- For no more than 3 seconds, connect a fused jumper wire between:
- HVAC module C294a-1, circuit 1205 (BK) and HVAC module C294a-20, circuit 1129 (BN/WH).
- HVAC module C294a-26, circuit 1566 (RD/YE) and HVAC module C294a-19, circuit 1128 (GY/LB).

- For no more than 3 seconds, connect a fused jumper wire between:
- HVAC module C294a-26, circuit 1566 (RD/YE) and HVAC module C294a-25, circuit 1137 (YE/LG).
- HVAC module C294a-1, circuit 1205 (BK) and HVAC module C294a-24, circuit 1136 (RD/WH).

- For no more than 3 seconds, connect a fused jumper wire between:
- HVAC module C294a-1, circuit 1205 (BK) and HVAC module C294a-25, circuit 1137 (YE/LG).
- HVAC module C294a-26, circuit 1566 (RD/YE) and HVAC module C294a-24, circuit 1136 (RD/WH).

- Does the resistance smoothly increase and/or decrease when the jumpers are connected?

Yes
INSPECT for broken door and linkage. REPAIR as necessary. If no condition is found, GO to D9.

No
GO to D8.

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D8 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR AN OPEN

NOTE: Due to limited connector accessibility, before carrying out this test step, visually inspect the wiring between the HVAC module and actuator for opens or shorts. If no damage is visually evident, proceed with the test.

- Ignition OFF.
- Disconnect: Floor/Panel Door Actuator C234 or Defrost Door Actuator C232.
- Measure the resistance between:
- For floor/panel door actuator: HVAC module C294a-20, circuit 1129 (BN/WH) and floor/panel door actuator C234-6, circuit 1129 (BN/WH).
- For defrost door actuator: HVAC module C294a-25, circuit 1137 (YE/LG) and defrost door actuator C232-6, circuit 1997 (BN/YE).

- Measure the resistance between:
- For floor/panel door actuator: HVAC module C294a-19, circuit 1128 (GY/LB) and floor/panel door actuator C234-1, circuit 1128 (GY/LB).
- For defrost door actuator: HVAC module C294a-24, circuit 1136 (RD/WH) and defrost door actuator C232-1, circuit 1136 (RD/WH).

- Are the resistances less than 5 ohms?

Yes
INSPECT for binding or broken linkage. REPAIR as necessary. If no condition is found, INSTALL a new door actuator. TEST the system for normal operation.

No
REPAIR the circuit(s) for an open. TEST the system for normal operation.

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D9 MODULE ACTUATOR POSITION CALIBRATION

NOTE: The purpose of the module actuator position calibration is to allow the HVAC module to reinitialize and calibrate the actuator stop points. To carry out the calibration, follow the steps below.

- Ignition OFF.
- Inspect the module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect: EMTC Module C294a.
- Ignition ON.
- Select any position except OFF.
- NOTE: The HVAC module will now initialize and calibrate the actuators. Calibration of the actuators will take approximately 30 seconds.
- Operate the system.
- Does the concern return?

Yes
INSTALL a new HVAC module. TEST the system for normal operation.

No
The system is now operating correctly. The concern may have been caused by a foreign object in the HVAC case or temporary binding that restricted actuator door travel. CHECK any actuator external linkage. If condition recurs, INSPECT actuator linkage and door for binding and CHECK HVAC case for foreign objects.

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