For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Check for a thermostat stuck open or wrong type of thermostat. Is the thermostat stuck open or of the wrong type. | -- | Go to step 2 | Go to step 3
2 |

1. Install the thermostat of the proper type and heat range. Refer to Engine Coolant Thermostat Replacement .
2. Does the engine reach normal operating temperature?

. Does the heater blow hot air?

--

System OK

Go to step 3

3 | Check for coolant below the coolant add or low .mark. Refer to Cooling System Draining and Filling . Is the coolant below the cold add mark or hot full mark in the coolant recovery reservoir? | -- | Go to Step 4 | --
4 | Add coolant to the full (add cold mark) or full (add hot mark) of the coolant recovery reservoir . | -- | -- | System OK