One of three things:
1. Low coolant level. While you are checking the level, ask yourself. When was the last time you have the coolant system flushed? You may also have "air pockets" in the cooling system. Have you ever have to add fluid into the cooling system? If you or a service station used water, instead of coolant, that will reduce the quality and efficiency of the entire system.
2. Thermostat stuck open. Locate your radiator hoses. Grasp the hoses (one at a time) and squeeze them. Are they both warm to touch? If they are, the thermostat is possibly good. If one of them is warmer than the other, replace the thermostat.
3. Restricted heater core. This goes back to #1. If the cooling system has not been flushed for the past say 30K miles, you may have a lot of gunk in the system that prevents coolant flow, especially if you have been adding water or low quality coolant.
Follow the diagnostic from 1, 2, and then 3.
Wednesday, January 21st, 2009 AT 6:27 PM