Mystery burning smell when running climate control

[HawkeyeScott]

Just discovered yesterday and then confirmed this morning. If I switch the climate control setting to blow onto the floor, there's a very distinct hot/burning smell coming into the cab. This happens when the AC OR heater is on. It happens when set to the 'bi-level' (dash and floor), or just the floor. As soon as I switch and blow heat or cold air through the dash vents only, the smell goes away.

Any idea what's happening when I send air through the floor vents?

Not sure it has anything to do with anything, but the smell comes a few days after a shop put on a new expansion valve to as a remedy the AC system blowing air that wasn't very cold.

 

[HawkeyeScott]

This is a 2000 Durango, 4.7L, by the way. 119K miles.

 

[Bluestream]

Valve cover gaskets may need to be changed. Oil leaks down on the exhaust manifold

 

[HawkeyeScott]

I appreciate it. But there are no leaks, and it doesn't smell like oil. Definitely seems to be an electrical issue.

 

[loyd]

Take it back to the shop that did the work and let them fix their screwup!

 

[ironman_gq]

I've had the resistor modules let the magic smoke out slowly, usually it's one resistor in the module so it only gets hot at certain fan speeds until the resistor finally blows and you lose that speed on the blower. Not sure if that's what it is but it could be a place to start.

 

[HawkeyeScott]

Thanks a lot. I've been reading about the resistor module. The smell doesn't come with varying fan speeds though, just in the settings that direct where the air blows. Do those modules also control the directional settings?