Recently with the help of this forum I fixed one of the problems I found with a 1999 Jeep Cherokee I recently purchased. Replacing the heater blender door actuator made the heater work just as it should...I'd like to thank those that helped me with that problem but I was hoping replacing the actuator would also fix another problem I seem to be having...

Once the vehicle has been running for a short while, I sometimes get a smell that smells just like burning plastic... At first it isn't too bad but after a few minutes it gets worse (My first guess is that this is because something plastic is getting too hot).

So far I haven't figured out where it is coming from. And I don't smell it all the time... part of the problem is I haven't had the jeep long enough or had the time to work on it and tell exactly where the smell is coming from.. And I don't want to burn up something.. Particularly if it's something important....

I am not 100% sure of this but if I run the vehicle with the heater **** in the off or a cab air recirculating position I don't get the smell... I think I do get the smell when ever the heater control **** is in a position that draws "Fresh" intake air into the cab... This makes me think that maybe the part(s) getting hot are in the engine compartment near the fresh air intake vent...

I haven't figured out exactly where this intake vent is. I have looked in the engine compartment but haven't seen anything obvious or smoke...
And I haven't noticed any other problems.

Unfortunately the only way I can think of to trouble shoot it is to start the engine, let it run and look for something getting hot that shouldn't... Hopefully I can find the problem before something bad happens...

Bobby

 

Did you have the smell before the blender door actuator fix already, or diid it occur after this? And with heater ****, you actually mean the mode selector? Or the temp selector?

Trying to chase a smell is even more difficult that a sound and almost impossible to advice on over the internet. We can't be there to smell it, so you will need to try and locate it further.
But if you select cabin air recycle and dont have the smell, than yes that would suggest i'ts coming in with the outside air...

 

Any fluids dripping and burning on the exhaust?
The ignition switch connector and HVAC blower connector like to overheat and melt too, might take a quick look at them.

 

Yes the smell was there before I fixed the blender door actuator. Once I figured out there was an actuator and it was bad, I was hoping that it was the cause of the smell (the smell is similar to that of burning electrical parts) but the smell returned after replacing the actuator... And yes by heater **** I meant the mode selector.