Pinpoint Test T: The Auxiliary Blower Motor Is Inoperative
Climate Control System
Pinpoint Tests
Pinpoint Test T: The Auxiliary Blower Motor is Inoperative
Refer to Wiring Diagram Set 52, Auxiliary Climate Control for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the auxiliary blower motor relay 1 coil and switch contact is supplied voltage. The coil receives ground from the HVAC module if any auxiliary blower speed but OFF is selected. When the relay coil is grounded, the relay is energized and voltage is delivered to the auxiliary blower motor. Ground for the auxiliary blower motor is provided through the auxiliary blower motor resistor. The auxiliary blower resistor is grounded.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Auxiliary blower motor
- Auxiliary blower motor relay 1
- Auxiliary blower motor resistor
- HVAC module
PINPOINT TEST T: THE AUXILIARY BLOWER MOTOR IS INOPERATIVE
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T1 CHECK CIRCUIT CHA05 (BN/WH) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor C4106 (Expedition/Navigator) or C4334 (Expedition EL/Navigator L) .
- Ignition ON.
For Expedition/Navigator only
- For Expedition/Navigator only, measure the voltage between auxiliary blower motor C4334-1, circuit CHA05 (BN/WH), harness side and ground.
For Expedition EL/Navigator L only
- For Expedition EL/Navigator L only, measure the voltage between auxiliary blower motor C4106-2, circuit CHA05 (BN/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T6.
No
GO to T2.
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T2 CHECK CIRCUIT SBB34 (YE/RD) FOR VOLTAGE
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Relay 1 .
- Ignition ON.
- Measure the voltage between the auxiliary blower motor relay 1 socket pin 5, circuit SBB34 (YE/RD) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T3.
No
VERIFY Battery Junction Box (BJB) fuse 34 (30A) is OK. If OK, REPAIR circuit SBB34 (YE/RD) for an open. TEST the system for normal operation.
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T3 CHECK CIRCUIT CBP46 (WH/BU) FOR VOLTAGE
- Measure the voltage between the auxiliary blower motor relay 1 socket pin 2, circuit CBP46 (WH/BU) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to T4.
No
VERIFY Smart Junction Box (SJB) fuse 46 (7.5A) is OK. If OK, REPAIR circuit CBP46 (WH/BU) for an open. TEST the system for normal operation.
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T4 CHECK CIRCUIT CH112 (VT/WH) FOR GROUND
- With the auxiliary blower on, measure the resistance between the auxiliary blower motor relay 1 socket pin 1, circuit CH112 (VT/WH) and ground.
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the relay component test on the auxiliary blower motor relay 1. If OK, REPAIR circuit CHA05 (BN/WH) for an open. TEST the system for normal operation.
No
GO to T5.
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T5 CHECK CIRCUIT CH112 (VT/WH) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module - Dual Automatic Temperature Control (DATC) C228B or HVAC Module - Electronic Manual Temperature Control (EMTC) C2357B .
- Measure the resistance between HVAC module - DATC C228B-2 or HVAC module - EMTC C2357B-2, circuit CH112 (VT/WH), harness side and auxiliary blower motor relay 1 socket pin 1, circuit CH112 (VT/WH).
- Is the resistance less than 5 ohms?
Yes
GO to T8.
No
REPAIR circuit CH112 (VT/WH) for an open. TEST the system for normal operation.
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T6 CHECK CIRCUIT CHA06 (YE/VT) FOR GROUND
- Ignition OFF.
For Expedition/Navigator only
- For Expedition/Navigator only, measure the resistance between auxiliary blower motor C4334-2, circuit CHA06 (YE/VT), harness side and ground.
For Expedition EL/Navigator L only
- For Expedition EL/Navigator L only, measure the resistance between auxiliary blower motor C4106-1, circuit CHA06 (YE/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new auxiliary blower motor. REFER to Climate Control Service and Repair. TEST the system for normal operation.
No
GO to T7.
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T7 CHECK CIRCUIT GD151 (BK/GN) FOR GROUND
- Ignition OFF.
- Disconnect: Auxiliary Blower Motor Resistor C4343 (Expedition/Navigator) or C4107 (Expedition EL/Navigator L) .
For Expedition/Navigator only
- For Expedition/Navigator only, measure the resistance between auxiliary blower motor resistor C4343-2, circuit GD151 (BK/GN), harness side and ground.
For Expedition EL/Navigator L only
- For Expedition EL/Navigator L only, measure the resistance between auxiliary blower motor resistor C4107-2, circuit GD151 (BK/GN), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
CARRY OUT the component test on the auxiliary blower motor resistor Climate Control System. If OK, REPAIR circuit CHA06 (YE/VT) for an open. TEST the system for normal operation.
No
REPAIR circuit GD151 (BK/GN) for an open. TEST the system for normal operation.
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T8 CHECK THE HVAC MODULE CONNECTION
- Inspect the HVAC 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. REFER to Climate Control Heating Ventilation Air Conditioning (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. TEST the system for normal operation.
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