Auto Air Conditioning & Heater Repair: Buick century defroster, buick century, heater core

Question
I was having an issue with the heater when it ran on high, seemed to pull power from the headlights.  I had my local shop check it and all they did was clean out the vents. They thought it was the heater switch.  Now though, I am having major problems.  I can't run the heater without smoke coming out of the vents. When I try to use the defroster, the warmer temperature actually fogs over the window. It seems to help to run it on the coldest setting but I can't see out of the windshield.  I called the shop back and they wanted to check the heater core. The temperature seems to be fine.  Any suggestions before I take it in ?  I am in upstate NY in the middle of winter.... can't leave it this way for too long!

Answer
Hi Mindy

On high you may see a voltage drop especially if you are in cold weather.  Have them check your battery.  As to the smoke it sounds like your heater core may be gone.  Check your antifreeze  level if it is low then you are probably going to have to replace the heater core.  Let me know what they say and I'll try and help you.