For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
DEFINITION: Time required to defrost the windshield is longer than usual.
1 | Were you sent here from Symptoms or another diagnostic table? | Go to Step 2 | Go to Symptoms - HVAC Systems - Manual
2 |

1. Start the engine.
2. Select the DEFROST mode.
3. Select the maximum blower speed.

Does sufficient air flow from the defroster outlets?

Go to Step 3

Go to Step 11

3 | Measure the engine operating temperature. Does engine reach normal operating temperature? | Go to Step 4 | Go to Step 9
4 |

1. Select the minimum blower speed.
2. Select the warmest temperature setting.
3. Feel the temperature of the inlet and outlet hoses at the heater core.

Does the inlet heater hose feel warmer than the outlet heater hose?

Go to Step 12

Go to Step 5

5 | Is the vehicle equipped with A/C? | Go to Step 6 | Go to Step 14
6 | Test the operation of the A/C compressor clutch. Does the A/C compressor clutch engage? | Go to Step 8 | Go to Step 7
7 | Repair the A/C compressor clutch. Refer to Air Conditioning Compressor Malfunction . Is the repair complete? | Go to Step 15 | --
8 | Perform the A/C system performance test. Refer to Air Conditioning (A/C) System Performance Test . Is the A/C system operating within the specifications? | Go to Step 10 | Go to Step 13
9 | Repair the low engine temperature concern. Refer to Engine Fails To Reach Normal Operating Temperature . Is the repair complete? | Go to Step 15 | --
10 | Inspect for correct operation of the recirculation door. Is the recirculation door operating correctly? | Go to Step 15 | Go to Step 14
11 | Repair the air delivery concern. Refer to Air Delivery Improper . Is the repair complete? | Go to Step 15 | --
12 | Repair the heating concern. Refer to Heating Performance Diagnostic . Is the repair complete? | Go to Step 15 | --
13 | Repair the A/C performance concern. Refer to Air Conditioning (A/C) System Performance Test . Is the repair complete? | Go to Step 15 | --
14 | Repair the recirculation door concern. Refer to Air Recirculation Malfunction . Is the repair complete? | Go to Step 15 | --
15 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2