C: DEFROST DOES NOT OPERATE

PINPOINT TEST C: DEFROST DOES NOT OPERATE

C1 CHECK FOR VACUUM TO FUNCTION CONTROL

- Start engine and allow engine to idle.
- Disconnect A/C, heater vacuum source tube (black), check for vacuum.

- Is vacuum present?

- Yes
Go to C2.

- No
Service vacuum source tube (black) as required. Restore vehicle. Retest system.

C2 CHECK DEFROST DOOR OPERATION

- Turn A/C control to the defrost position.
- Locate windshield defroster door vacuum control motor.
- Check for vacuum at yellow vacuum tube.

- Is vacuum present at each vacuum tube?

- Yes
Replace defrost door vacuum control motor. Go to C3.

- No
Service suspect hose for cut or damage. Restore vehicle. Retest system.

C3 CHECK DEFROSTER TEMPERATURE

- Allow engine to run until operating temperature is achieved.
- Move A/C control to FLOOR position.
- Adjust A/C control to full-heat position.
- Actuate heater blower motor switch -

Is defrost temperature OK?

- Yes
Go to C4.

- No
Go to Heater Core Test and service as outlined. Retest system.

C4 CHECK BLOWER MOTOR OPERATION

- Actuate blower motor in all positions.

- Did blower motor operate properly?

- Yes
Restore vehicle. Retest system.

- No
Go to Pinpoint Test E.