Pontiac Repair: heater core? on a 2002 montana, coolant level, coolant leak

Question
I have a 2002 pontiac montana.  It's December and the windows fog up on me.  I don't smell antifreeze inside the van, but a faint smell outside.  Inside on the temperature gauge it seems to be a bit higher when you sit and idle, and a bit lower as you are driving.  When you sit and idle it seems to keep the windows a little bit less foggy.  Does this seem like the heater core?  I don't want to get taken at the repair shop.

Answer
Hi Brian:

I don't think so if you don't have a smell inside the car when it's hot or when it's hot and the van has been of for a few minutes and then turned back on again. The smell under the hood is a dead give a way that you have a coolant leak if the coolant level is low it would make the temp gauge erratic and the heat erratic as well. These vans are noted for lower intake manifold gaskets doing bad and also from time to time the right side head gasket going bad. If the heater isn't working correctly the defogger will not work right as well. Also being that it's colder out and damper the window fogging is not out of the ordinary. I would have a coolant pressure test done to find your leak. good luck!