For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
DEFINITION: The engine fails to reach the normal operating temperature. Cool air is felt from the heater.
1 | Check the thermostat. Is the thermostat stuck open or was the wrong type of thermostat previously installed? | -- | Install a new thermostat of the correct type and heat range. | Go to Step 2.
2 | Check the coolant level. Is the coolant level below the ADD mark? | -- | Add coolant. | Go to Step 3.
3 | Inspect the radiator. Is the radiator plugged or is there a faulty cap? | -- | Check the radiator or the cap. | Go to Step 4.
4 | Inspect the cylinder head. Is the cylinder head or block cracked or plugged? | -- | Repair the cylinder head or block as necessary. | --