Normally this burning smell could be: electric heat strips or gas furnace start up if for the first time in a while. Next if you have already been running the unit for a while it may be the blower motor over heating. Do you have gas or electric heating.
I hope you are not using pleated filters! They really make your system work hard and usually cost you allot of extra money in utility costs!!!
Well honestly i dont see how the filter could be burning. Do you have an electronic air cleaner attached to your Electric furnace?
The cheep filter is called a poly filter or fiberglass filter... they usually run about two dollars at the builders supply store.
Ok let me be clear... Did you buy an electronic air cleaner and have it installed at your home?
This is part of your a/c system and can make the burning smell if you have one of these.
Thank you am i asking too many questions? Are you still wanting to locate the burning smell?
yes. I can help you further if you want but it seems you are not wanting me to ask you questions about your system so that i can help you. Am i miss reading you?
Your motor may have sustained damage...i don't know for sure. However you have been smelling the burning smell and i think it is important for us to figure what is causing it.
Replacing the filter is a long range solution. The short term solution is to remove the pleated filter and run the system for a few hours and see if this helps clear the burning smell.
Try this and see if the burning smell goes away. I want to thank you for contacting Just Answers! We appreciate you. If i have helped you please click on the ACCEPT link. If you have any other questions i would be happy to answer them!