Air Conditioning and Coolant
Heater Cores and Blower Fans
Car Heaters

Why would the heater blow cold air while driving but warm up when sitting still?


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2011-09-13 17:23:47
2011-09-13 17:23:47

When this happens it is typically because your antifreeze and water mix (coolant) isn't correct. You want 50% antifreeze and 50% water to create the right coolant mix. The antifreeze will keep the car running cool while the water allows it to stay warm enough to provide heat in your vehicle.

When you are sitting still the water pump isn't moving at full speed so the coolant isn't flowing through the radiator as fast and heats up a little more. As well, you are not moving so the coolant running through the radiator isn't being cooled by any forced air like it is when you are driving.

Bottom line, you need to add water to your radiator. If it is full then I would suggest getting it flushed and put the correct 50/50 mix in the vehicle. Whoever filled your coolant obviously used 100% antifreeze.


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