2000 Mercury Sable

Heater problem
2000 Mercury Sable 6 cyl Front Wheel Drive Automatic 128000 miles

My car has no heat at all----when you turn on the heat you can smell coolant it is freezing here and the moisture from the heater has caused my windows to ice up (i was runing the heater to try to unfog the windows it only made it worse)----Also my car is overheating it over heats when you are driving slow (like at a stop or stuck in traffic) a back yeard michanic said heads and somone else said it could be a heater core How could I know which is the problem? Is there any extra signs for the two? Please let me know asap ---- I have a 1999 mercury sable
December 22, 2008.

The smell and window icing tell me heater core leaking. If coolant is low that would cause your overheating. Assume it is cold where you live. Do you see white smoke a water comming from tail pipe? Doea oil look normal or a little like chocolate malt? Yes to either question head gasket failure.
Let me know
Merry Christmas

Dec 22, 2008.
Let me add some more details----I have replaced the radiator and the thermostat because I bought the car and the radiator was rusted and leaking I also had to replace the thermostat due to rust----the mechanic I had look at it told me the heads are bad but I the oil is not milky and the car doesnt overheat all the time only when the car is at a stop and when you are in slow traffic and not moving over 5mph I went somewhere else a second opinion told me that the cause of the overheating was from the heater core being out, and everything else was fromt hat also---symthoms the car is overheating, when you turn the heat on no heat and it smells like antifreeze, it is winter and of course my inside windows iced up and there is leaking under the passenger side dash it is not bad just a little. If it is the heads I am not fixing the car thats going to cost more than the car is worth because there are a few other small issues----I need to know the tell tale signs between heads or heater core----thanks

Dec 22, 2008.
O.K. Heater core leaking will not cause car to overheat It will if coolant is run low.
If headgaskets are faulty and leaking that will cause car to overheat.
Over heating at low speeds can be caused if cooling fans are not operating. Verify they are operating.

Dec 23, 2008.