Pinpoint Test S: The Blower Motor Does Not Operate Correctly - DATC
Climate Control System
Pinpoint Tests
Pinpoint Test S: The Blower Motor Does Not Operate Correctly - DATC
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the relay coil and switch is supplied voltage. When the blower motor relay coil receives a ground from the HVAC module, the relay coil is energized and voltage is delivered to the blower motor and the blower motor control module from the relay. Ground for the motor is provided from the blower motor speed control. Ground is provided for the blower control module. The HVAC module sends a Pulse Width Modulated (PWM) signal to the blower motor speed control to control the blower speed.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Blower motor speed control module
- HVAC module - Dual Automatic Temperature Control (DATC)
PINPOINT TEST S: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY - DATC
-------------------------------------------------
S1 VERIFY THE BLOWER MOTOR OPERATION
- Ignition ON.
- Press the PANEL button on the HVAC module - DATC. Adjust the blower motor setting to LO and then to HI.
- Does the blower motor operate at any setting?
Yes
If the blower motor operates always in HI, GO to S2.
If the blower motor is always ON, GO to S5.
No
GO to Pinpoint Test R. Pinpoint Test R: The Blower Motor is Inoperative - DATC
-------------------------------------------------
S2 CHECK CIRCUIT VH301 (YE/BU) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Blower Motor Speed Control Module C297.
- Ignition ON.
- Does the blower motor operate?
Yes
REPAIR circuit VH301 (YE/BU) for a short to ground. TEST the system for normal operation.
No
GO to S3.
-------------------------------------------------
S3 CHECK CIRCUIT VH101 (WH/VT) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module - DATC C228B.
- Ignition ON.
- Measure the voltage between blower motor speed control module C297-3, circuit VH101 (WH/VT), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit VH101 (WH/VT) for a short to voltage. TEST the system for normal operation.
No
GO to S4.
-------------------------------------------------
S4 CHECK CIRCUIT VH101 (WH/VT) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between blower motor speed control module C297-3, circuit VH101 (WH/VT), harness side and HVAC module - DATC C228B-16, circuit VH101 (WH/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor speed control module. TEST the system for normal operation.
No
REPAIR circuit VH101 (WH/VT) for an open. TEST the system for normal operation.
-------------------------------------------------
S5 CHECK CIRCUIT CH402 (YE/GN) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Blower Motor C288.
- Ignition ON.
- Measure the voltage between blower motor C288-2, circuit CH402 (YE/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
REPAIR circuit CH402 (YE/GN) for a short to voltage. TEST the system for normal operation.
No
INSTALL a new blower motor speed control. TEST the system for normal operation. If the blower motor still does not operate correctly, GO to S6.
-------------------------------------------------
S6 CHECK THE HVAC MODULE CONNECTION
- Inspect the module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HVAC module. 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. REPEAT the self-test. TEST the system for normal operation.
-------------------------------------------------