For 1990-2009 cars

1. Perform the defrost mode function test to ensure proper system operation. Refer to Function Test .

• | The A/C compressor clutch is engaging.

• | The air flow from the proper outlets.

2. Inspect for an obstruction in both of the defroster nozzles.

Perform the following steps, as necessary:

• | Remove any foreign objects.

• | Repair any loose instrument panel pad that blocks an outlet.

3. Inspect for the proper operation of the defroster air valve.
4. Inspect for one of the following conditions.

Replace the defroster vacuum actuator or hose if one of the following conditions exist:

• | A faulty defroster air valve vacuum actuator

• | A faulty defroster air valve vacuum hose

5. Inspect for insufficient heating.

Refer to Heating Insufficient .