For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 |

1. Connect the Scan Tool .
2. Start the engine.
3. Monitor the engine coolant temperature.

Does the coolant temperature increase steadily to the indicated value (normal operating temperature) within 15 minutes?

approximately 90°C (195°F)

Go to Step 2

Go to Step 5

2 | Feel the inlet and the outlet hoses of the heater core. Do both the inlet hose and the outlet hose feel hot? | -- | Go to Step 3 | Go to Step 6
3 | Inspect the heater core for bent fins or other obstructions. Did you locate and repair an obstruction? | -- | System OK | --
4 |

1. Inspect the cooling system for signs of leakage.
2. Fill the coolant system.
3. Bleed the air from the coolant system. Refer to Cooling System Draining and Filling in Engine Cooling.

Did you add coolant to the system?

--

System OK

--

5 | Replace the faulty thermostat. Refer to Engine Coolant Thermostat Replacement in Engine Cooling. Is the repair complete? | -- | System OK | --
6 |

1. Inspect the hoses and the pipes for kinks or other obstructions.
2. Turn the A/C system off. Listen to the area below the heater core.

Heater core obstructions usually cause a squishing noise.

3. Flush or replace the obstructed heater core.

Refer to Flushing in Engine Cooling or refer to Heater Core Replacement in HVAC.

Is the repair complete?

--

System OK

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