hey lately ive been getting this off and on again burning smell that gets pretty bad. It was a lot worse before I changed my cabin filter and now that i did change it, about 50% of the smell went away. Here are some things Ive observed.
The smell is coming from the vents. The engine does not smell like that, nor do my fog / headlights. Smells like plastic burning? Only occurs hours after I have turned the air on, recirculation button, defogger,etc. Smells when the air is set to cold or warm - doesn't matter which. Thanks

 

Maybe the vent fan (that might not be the right name, I'm on cold meds and my brain isn't working right) motor is trying to overheat on you. Could be worth a check, but I'm not sure how much of the dash you would have to dismantle to get to it.

 

if my head light harness/wiring is burning - wouldnt the lights dim or not work?

 

It depends... as heat goes up, so does resistance. As resistance across a circuit goes up, the voltage each load (including the resistance in the wiring itself) receives goes down. It could be that the wiring is burning the insulation, which wouldn't necessarily mean more resistance across the circuit (yet).

My guess would be more towards the blower motor overheating since you said the engine/headlights don't smell like it.

 

would the blower motor smell like burning plastic?
is the blower motor on when the recirculation button is on?

and why is it that it only smells like it sometimes and then goes away?

when i changed the cabin filters, the smell went away for weeks... and then it came back.

and how and where is the blower motor (01 civic)

 

Honestly, I don't know what an overheating blower motor would smell like (not having ever had to deal with one); if it's overheating, it could be melting wires/wire insulation, which would smell sort of like burnt plastic.

 

where is it located anyways?

 

I believe it's under the passenger side of the dash, but I'm not 100% sure on it.

*ninja edit: confirmed. supporting evidence

 

okay, i will look at this tomorrow. thanks again

 

The blower motor is behind the glove box. It can be removed by taking out three screws and disconnecting the connector. Might as well remove debris like leaves and mouse nests that have accumulated in it over time. Also check the recirculation and mode control motors under the dash.