my 2004 lincoln ls has about 47,00 miles on it. for the past week or so everytime i turn the heat or defrost on there is a burning smell. what could the cause of this problem be?? PLEASE HELP!!

i would have the vehicle checked for any leaks that may be present and the odor is being picked up by the hvac system.....
also check the exhaust system....i have seen where people run over some plastic ....etc and it melts on the hot exhaust and or catalytic converter and the fumes get into the cabin of the vehicle..
just some thoughts....

alright thank you