A: Heater Blower Motor Does Not Run at Any Speed

A1 CHECK BLOWER MOTOR CIRCUIT

- Start engine, set control to MAX A/C, set A/C blower motor to any speed. Proceed as follows if heater blower motor does not operate.

- Disconnect A/C blower motor speed control connector. Start engine, set control to MAX A/C and A/C blower motor on HI. Measure voltage between Pins 4 and 5 of A/C blower motor speed control. Should show battery voltage.

- Is voltage less than 10 volts?

- Yes
Check fuse, A/C blower motor Circuits 181 and 261 Crown Victoria/Grand Marquis, Circuit 371 on Town Car. Service as required.

- No
Go to A2.

A2 CHECK BLOWER MOTOR

- Reconnect A/C blower motor speed control connector and disconnect A/C blower motor from harness. Check for voltage across harness connector (261(0/BK) and 181 (BR/0) wires on Crown Victoria/Grand Marquis, 371 (P/W) on Town Car) with A/C blower motor on HI.

- Is the voltage measurement 10 volts or more?

- Yes
Replace A/C blower motor.

- No
Go to A3.

A3 BSC CHECK

- Disconnect A/C blower motor speed control connector and check voltage between Pins 3 and 5 of

- A/C blower motor speed control. (Should be 10 or more volts with A/C blower motor on HI.)

- Is voltage 10 volts or greater?

- Yes
Replace A/C blower motor speed control.

- No
Go to A4.

A4 CHECK CIRCUIT 754 (LG/W)

- Reconnect A/C blower motor speed control connector. With engine running and controls set to MAX

- A/C and A/C blower motor on HI, check voltage between ATC module Pin 5 and ground. Should be 10 or more volts.

- Is voltage 10 volts or greater?

- Yes
Service Circuit 754 (LG/W) between ATC module (Pin 5) and A/C blower motor speed control (Pin 3).

- No
Go to A5.

A5 VOLTAGE CHECK AT PIN 3

- With ignition switch in RUN and control set for MAX A/C, check for battery voltage to ground at Pin 3 of the ATC A/C damper door switch.

- Is there battery voltage?

- Yes
Go to A6.

- No
Go to A7.

A6 CHECK VOLTAGE AT PIN 6

- With ignition switch in RUN and control set for battery voltage to ground at Pin 6 of the ATC A/C damper door switch.

- Is there battery voltage?

- Yes
Replace control module.

- No
Replace A/C damper door switch.

A7 CHECK VOLTAGE AT A/C DAMPER DOOR SWITCH

- Check for battery voltage to ground at Pin 6 of the ATC A/C damper door switch.

- Is there battery voltage?

- Yes
Retest. Go to A1.

- No
Go to A8.

A8 CHECK VOLTAGE AT PIN 1

- With ignition switch in RUN and A/C damper door switch at MAX A/C, check for battery voltage to ground at Pin 1 of A/C damper door switch.

- Is there battery voltage?

- Yes
Go to A9.

- No
Go to A10.

A9 CHECK VOLTAGE AT PIN 2

- With ignition switch in RUN and A/C damper door switch at MAX A/C check for battery voltage at Pin 2 of A/C damper door switch.

- Is there battery voltage?

- Yes
Replace A/C damper door switch.

- No
Check Circuit between Pins 1 and 2 of A/C damper door switch.

A10 CHECK VOLTAGE AT A/C DAMPER DOOR SWITCH

- With ignition switch in RUN and A/C damper door switch at MAX A/C, check for battery voltage to ground at Pin 2 of A/C damper door switch.

- Is there battery voltage?

- Yes
Check circuit between Pins 1 and 2 of A/C damper door switch.

- No
Go to A11.

A11 CHECK FUSE

- Check fuse F-5 (Crown Victoria, Grand Marquis) or F-8 (Town Car) in fuse panel for continuity.

- Is fuse functional?

- Yes
Check circuit between fuse panel and A/C damper door switch for open.

- No
Service circuit and replace fuse. Check system for correct operation.