I have a 99 Monte Carlo & randomly while running the heater or warming up the vehicle in the morning, I will get a very toxic smell in the interior. Best way to describe it is a sort of burning plastic smell but much worse. It started with the extreme cold we have been experiencing. Smell can be faint at times or strong enough that I have to roll down the windows or open door while driving if windows are frozen! I have taken it to the shop but of course it will not do the smell there & they can not find anything. I am concerned that it may be consistently releasing this fume at lower levels that I don't detect, which in turn concerns me for the safety of my passengers & myself.

SOURCE: Gas fumes very strong in car.

need to have checked possibly an injector leaking car is not safe to drive if you have a fuel leak. look in engine compartment and see if you can see a leak

SOURCE: Interior Smell, musty mold smell

run water over the winshield ..keep eye on the fire wall and sides. also check the florr if is wet. water is likin somewere

SOURCE: Heater Core Leaking

you could quick fix! but you will have no heat, 1st under the hood, look at the back of motor, follow all you're radiator hoses, take two hoses off the heater core stick a pipe that is big enough then clamp the pipe down. to both sides of hoses to the pipe you will eventually have to replace heater core!!

SOURCE: strong antifreeze smell when running the heater in

Usually a smell of antifreeze in the cab when the heater is running is a sign the heater core is leaking. Just becasue you dont see a leak at this time doesn't mean there isn't one. It might small enough that the haet from the core is burning off the leaking antifreeze. I would suggest replacing the core before you get in one day and there is a puddle on your floorboard. Or if you go to a local parts store and rent a cooling system pressure tester, wait until the vehicle is cold, pressure the system to 12 lbs and then check for leaks. Hope this helps you out......

Testimonial: "that is what i also thought, no puddle yet, just waiting. I tried a sealant for now, but will get a heater core"

SOURCE: 2001 chevy monte carlo is overheating when driving

Hi;
If your engine cools down when moving fast, you either have a problem with your water pump or your electric fans that cool off your radiator and a/c condenser. This is controlled by a temperature switch, but these fans should kick on instantly when A/C is selected.