Q: Heat Defroster Not Functioning Correctly

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All of a sudden, when I turn on the heater, my windshield and side windows fog up and do not clear. Also, there is a smell when the heater is turned on. The fogging of windows seems to be somewhat intermittent.. Example Driving to my daughter's Friday afternoon, the windshield and side windows fogged and would not clear. Later that evening driving home, the defroster worked fine. The heater heats fine, it is the smell and defroster that seems to be affected. Do you know what is happening and how much it will cost to repair?

Thanks,

My car has 159715 miles.
My car has an automatic transmission.

The smell and fogged windows is an indication you are leaking coolant out of the heater core in the dash heater. You should check the engine coolant level to see if it is low indicating the leak. If system is low then look for coolant coming from evaporator drain for the a/c heater box and also from lower floor vents inside car. If leaking then the heater core will need to be replaced.

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