Normal Operation

WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

Under normal operation, the blower motor relay coil receives a ground from the HVAC module through circuit CH123 (VT/GN). The coil receives ignition voltage through circuit CBP45 (YE). Voltage is supplied to the relay switch contact through circuit SBB35 (BU/RD). When the relay coil is energized, voltage is delivered to the blower motor speed control through circuit CH402 (YE/GN). Ground for the blower motor speed control is provided by circuit GD115 (BK/GY). Voltage for the motor is provided through circuit VH301 (YE/BU) from the blower motor speed control. Ground for the motor is provided through circuit VH219 (GY) from the blower motor speed control. The HVAC module sends a Pulse-Width Modulation (PWM) signal to the blower motor speed control through circuit VH101 (WH/VT) to control the blower speed.

DTC DESCRIPTION TABLE

DTC Description	Fault Trigger Conditions
B10AF:12 - Blower Fan Relay: Circuit Short to Battery	The module senses excessive voltage on the relay coil ground circuit, indicating a short directly to voltage.
B10AF:14 - Blower Fan Relay: Circuit Short to Ground or Open	The module senses no voltage on the relay coil ground circuit, indicating an open or a short directly to ground.
B10B9:12 - Blower Control: Circuit Short to Battery	The module senses excessive voltage on the blower motor control PWM circuit, indicating a short directly to voltage.
B10B9:14 - Blower Control: Circuit Short to Ground or Open	The module senses no voltage on the blower motor control PWM circuit, indicating an open or a short directly to ground.

This pinpoint test is intended to diagnose the following:

Fuse(s)
Wiring, terminals or connectors
Blower motor relay
Blower motor speed control
HVAC module - Dual Automatic Temperature Control (DATC)
Blower motor

Under normal operation, the blower motor relay coil receives a ground from the HVAC module through circuit CH123 (VT/GN). The coil receives ignition voltage through circuit CBP45 (YE). Voltage is supplied to the relay switch contact through circuit SBB06 (BN/RD). When the relay coil is energized, voltage is delivered to the blower motor speed control through circuit CH402 (YE/GN). Ground for the blower motor speed control is provided by circuit GD115 (BK/GY). Voltage for the motor is provided through circuit VH301 (YE/BU) from the blower motor speed control. Ground for the motor is provided through circuit VH219 (GY) from the blower motor speed control. The HVAC module sends a Pulse-Width Modulation (PWM) signal to the blower motor speed control through circuit VH101 (WH/VT) to control the blower speed.

DTC B10AF:14 (Blower Fan Relay: Circuit Short to Ground or Open) - The module senses no voltage on the relay coil ground circuit, indicating an open or a short directly to ground.
DTC B10B9:14 (Blower Control: Circuit Short to Ground or Open) - The module senses no voltage on the blower motor control PWM circuit, indicating an open or a short directly to ground.

This pinpoint test is intended to diagnose the following:

Fuse(s)
Wiring, terminals or connectors
Blower motor speed control
HVAC module - Dual Automatic Temperature Control (DATC)