Pinpoint Test K: The Air Inlet Door Is Inoperative
Climate Control System
Pinpoint Test K: The Air Inlet Door is Inoperative
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, to rotate the air inlet mode door actuator, the HVAC module supplies voltage and ground to the air inlet mode door actuator through the actuator motor circuits. To reverse the air inlet mode door actuator rotation, the HVAC module reverses the voltage and ground circuits.
The air inlet mode door actuator feedback resistor is supplied a 5-volt reference voltage and ground from the HVAC module. The HVAC module measures the resistance on the air inlet mode door actuator feedback circuit to determine the air inlet mode door actuator position by the position of the actuator feedback resistor wiper arm.
During an actuator calibration cycle, the HVAC module drives the air inlet mode door until the door reaches both internal stops in the HVAC case. If the air inlet mode door is temporarily obstructed or binding during a calibration cycle, the HVAC module may interpret this as the actual end of travel for the door. When this condition occurs and the HVAC module commands the actuator to its end of travel, the air inlet may not be from the expected source.
- DTC B1242 (Air Flow Recirculation Door Driver Circuit Failure) - The module senses no change in actuator feedback voltage when the actuator motor has been energized.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Air inlet door actuator motor
- HVAC module
- Stuck or bound linkage or door
PINPOINT TEST K: THE AIR INLET DOOR IS INOPERATIVE
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K1 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE
- Ignition OFF.
- Disconnect: HVAC Module C228A.
- Disconnect: HVAC Module C228B.
- Measure the resistance between HVAC module C228B-8, circuit 436 (RD/LG), harness side and HVAC module C228A-20, circuit 438 (RD/WH), harness side.
- Is the resistance greater than 500 ohms?
Yes
GO to K3.
No
GO to K2.
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K2 CHECK POTENTIOMETER FEEDBACK CIRCUITS FOR A SHORT TOGETHER
NOTE: Access to the connector in the following step is difficult. Before performing this step, visually inspect the actuator and its harness for obvious damage. If no damage is evident, proceed with the test.
- Measure the resistance between HVAC module C228B-8, circuit 436 (RD/LG), harness side and HVAC module C228A-20, circuit 438 (RD/WH), harness side.
- While measuring the resistance above, disconnect the following components one at a time, in order. Stop disconnecting components if the measured resistance rises above 500 ohms.
- Air inlet door actuator C289
- LH blend door actuator C2092
- RH blend door actuator C2092
- Did the resistance rise above 500 ohms?
Yes
INSTALL a new actuator (the last one to be disconnected). CONNECT the actuator electrical connectors before the HVAC module connectors. This will allow the new actuator to be calibrated when the HVAC module is reconnected. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
Visually INSPECT the harness between the actuators and the HVAC module for obvious damage. REPAIR as necessary. If no damage is evident, INSTALL a new floor door actuator and panel/defrost door actuator. If a new actuator is installed, CONNECT the actuator electrical connectors before the HVAC module connectors. This will allow the new actuator to be calibrated when the HVAC module is reconnected. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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K3 CHECK POTENTIOMETER LOW- AND HIGH-SIDE RESISTANCE
- Measure the low-side resistance between HVAC module C228A-20, circuit 438 (RD/WH), harness side and HVAC module C228B-3, circuit 435 (YE/LB), harness side.
- Measure the high-side resistance between HVAC module C228B-8, circuit 436 (RD/LG), harness side and HVAC module C228B-3, circuit 435 (YE/LB), harness side.
- Is the resistance between 250 and 5,500 ohms?
Yes
GO to K4.
No
CARRY OUT the Air Inlet Door Actuator component test. If a new actuator is installed, CONNECT the actuator electrical connector before the HVAC module connector(s). This will allow the new actuator to be calibrated when the HVAC module is reconnected. If the actuator tests OK and: Component Tests and General Diagnostics
If the low-side resistance only is greater than 5,500 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 250 ohms, REPAIR circuits 435 (YE/LB) 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 5,500 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 250 ohms, REPAIR circuits 435 (YE/LB) and 436 (RD/LG) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
If both thehigh-side and low-side resistance is greater than 5,500 ohms, REPAIR circuit 435 (YE/LB) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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K4 CHECK CIRCUITS 435 (YE/LB) AND 438 (RD/WH) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between ground and:
- HVAC module C228B-3, circuit 435 (YE/LB), harness side.
- HVAC module C228A-20, circuit 438 (RD/WH), harness side.
- Is any voltage present?
Yes
REPAIR circuit 435 (YE/LB) or 436 (RD/LG) for a short to voltage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to K5.
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K5 CHECK CIRCUITS 435 (YE/LB) AND 436 (RD/LG) FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between ground and:
- HVAC module C228B-3, circuit 435 (YE/LB), harness side.
- HVAC module C228B-8, circuit 436 (RD/LG), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to K6.
No
REPAIR circuit 435 (YE/LB) or 436 (RD/LG) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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K6 CHECK THE RECIRC DOOR ACTUATOR OPERATION
NOTE: If a jumper fuse opens while carrying out this test step, repair the circuit(s) for a short.
- Ignition ON.
- With the fused jumper connections made as directed below, measure the resistance between HVAC module C228A-20, circuit 438 (RD/WH), harness side and HVAC module C228B-3, circuit 435 (YE/LB), harness side.
- Connect a fused jumper wire between:
- HVAC module C228A-9, circuit 1069 (OG/LB), harness side and HVAC module C228B-11, circuit 1566 (RD/YE), harness side.
- HVAC module C228A-10, circuit 660 (YE/LG), harness side and HVAC module C228A-2, circuit 57 (BK), harness side.
- Remove the fused jumpers.
- Connect a fused jumper wire between:
- HVAC module C228A-10, circuit 660 (YE/LG), harness side and HVAC module C228B-11, circuit 1566 (RD/YE), harness side.
- HVAC module C228A-9, circuit 1069 (OG/LB), harness side and HVAC module C228A-2, circuit 57 (BK), harness side.
- Does the resistance smoothly increase and/or decrease when the jumpers are connected?
Yes
INSPECT for broken door and linkage. REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If no condition is found, GO to K9.
No
GO to K7.
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K7 CHECK THE ACTUATOR MOTOR DRIVE CIRCUITS FOR AN OPEN
NOTE: Access to the connector in the following step is difficult. Before performing this step, visually inspect the actuator and its harness for obvious damage. If no damage is evident, proceed with the test.
- Ignition OFF.
- Disconnect: Air Inlet Door Actuator C289.
- Measure the resistance between HVAC module C228A-10, circuit 660 (YE/LG), harness side and the recirc door actuator C289-1, circuit 660 (YE/LG), harness side.
- Measure the resistance between HVAC module C228A-9, circuit 1069 (OG/LB), harness side and the recirc door actuator C289-6, circuit 1069 (OG/LB), harness side.
- Is the resistance 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. If no condition is found, GO to K8.
No
REPAIR the circuit(s) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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K8 CHECK THE ACTUATOR CONNECTION
- Disconnect the actuator connector.
- Check for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat the actuator connector.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new air inlet door actuator. If a new actuator is installed, CONNECT the actuator electrical connectors before the HVAC module connectors. This will allow the new actuator to be calibrated when the HVAC module is reconnected. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. TEST the system for normal operation.
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K9 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 and correctly seat all the HVAC module connectors.
- Ignition ON.
- Clear the DTCs.
- 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 and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HVAC module. REFER to Climate Control Service and Repair. TEST the system for normal operation.
No
The system is now operating correctly at this time. 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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