So, I just got my 1999 GL beetle. Runs and drives great. The heat or defrost doesn't work. Been told it could be heater core, exhaust leak, or clogged. Sometimes a small amount of smoke or exhaust comes through the vents if you turn the heat on, but no sweet smell. No water or moisture in floor boards. Also, the airbag light is on, which I've read on here that is associated with the heater core sometimes. Also, sometimes the temp light will come on and it's not overheating. Please help!