D: NO OPERATION IN ALL TEMPERATURE SETTINGS

PINPOINT TEST D: NO OPERATION IN ALL TEMPERATURE SETTINGS

D1 MANUAL A/C ELECTRIC BLEND DOOR ACTUATOR SYSTEM CHECK (CROWN VICTORIA, GRAND MARQUIS)

- Start vehicle and run engine until it reaches normal operating temperature.
- Turn on MAX a/C mode.
- Adjust A/C control to full-COOL (LEFT) and check for cool discharge air.
- Adjust A/C control to full-WARM (RIGHT) and check for warm discharge air.
- Vary A/C control from full-WARM to full-COOL.

- Did air temperature change?

- Yes
System is fully functional.

- No
Go to D2.

D2 MANUAL A/C ELECTRIC BLEND DOOR ACTUATOR SYSTEM FUSE CHECK (CROWN VICTORIA, GRAND MARQUIS)

- Check Fuse 5 at the fuse junction panel.

- Is fuse good?

- Yes
Go to D3

- No
Replace fuse and go to D1. If fuse blows again, check for shorts to ground in circuit 298 (P/O) and service as needed.

D3 MANUAL A/C ELECTRIC BLEND DOOR ACTUATOR SUPPLY VOLTAGE CHECK (CROWN VICTORIA, GRAND MARQUIS)

- Disconnect blend door actuator connector located on the heater air plenum chamber and accessed through the glove compartment opening.
- Using a voltmeter check for battery voltage between Circuit 298 (P/O) and Circuit 208 (GY).

- Is there B+?

- Yes
Go to D4.

- No
Check circuits 437 and 600 for shorts.

D4 A/C CONTROL SUPPLY VOLTAGE CHECK (CROWN VICTORIA, GRAND MARQUIS)

- Reconnect blend door actuator connector at the A/C evaporator core housing.
- Disconnect heater control connector from the back of the A/C control.

CAUTION: Never short across Circuits 436 (R/LG) and 600 (DB). This could cause destructive damage.

- Using a voltmeter, check for reference voltage.

- Is there reference voltage?

- Yes
Go to D5.

- No
Check wiring for opens/shorts. If wiring to potentiometer is good, replace the A/C control.

D5 A/C CONTROL POTENTIOMETER CHECK (CROWN VICTORIA, GRAND MARQUIS)

- Disconnect and remove control head potentiometer.
- Using a multimeter, check resistance between terminals 2 and 3.
- With potentiometer at full COOL (resistance should be 3000 OHMS).
- With potentiometer at full WARM (resistance should be 15 OHMS).

- Is resistance variable in between cool and warm?

- Yes
Replace the A/C electronic door actuator motor on heater air plenum chamber.

- No
Replace A/C control.