Burning smell with heat

[StaceyW]

I have an 04 lexus rx330 with 121,000 miles. Randomly (not always) while driving with the heat on I get a strong burning smell off the engine. What's happening????

[Lexus Owners Club]

Hi Stacey....welcome to the Forum

That sounds quite disturbing and I think I would seek a diagnosis from a reputable garage to track down the cause of the burning smell.

It may be some debris on the exhaust or similar or something more sinister.

Let us know what you find

[RX400h]

See if it continues if you switch the flow of air to upper, only. If it continues, switch to lower, only. 
I noticed that a burning smell is noticeable when the air flow is set to lower or both lower and upper vents. When I switch to lower, only, no flow is detected, yet the burning smell is intermittently noticeable. My theory is that the vent valve is not functioning correctly and may be drawing excessive current.

Also, have you changed or had changed the oil, lately? The filter oil tends to drip down on the exhaust pipe but if it is cleaned up thoroughly, the burning oil smell goes away after a few days or less of driving.