Car fogs up whenever I use the heater, and I mean fogs up to the point where I can't see anything.

It reeks of coolant whenever the heater is on as well.

Could it be the heater core? Or Temperature sensor? Or what?

 

I'm going to venture that your heater core is shot. Only way to know is pull everything out and inspect it.

 

yep, thats the Core. Have fun changing it out. My condolences go out to you.

 

GOOD LUCK be patient

 

actually the car goes up for sale mid next month.

I am going to let it become someone else's problem.

 

you know its very simple to replace the core...mayb a 2 hour job...only car i know where the dash doesnt have to be removed is the camaro and firebird. i replaced mine with a 7mm socket, some extentions and a 7mm wrench. thers an article in the tech centre on how to do it simply by taking off the dashboard and the passenger side lower dash.