My blower resistor died but Highspeed still worked. I replaced it with a new one the next day and now when I use the AC on the first 3 settings I get a bad smell, almost like exhaust or burned oil. But if I turn it on full speed the smell goes away. I am clueless to what is causing that. It won't smell if I just use the blower with no AC or heat that I can tell. Just the AC it seems. 2005 1500.

 

Have you looked under the hood for an oil leak? Unless you have the A/C on recirculate you're sucking in outside air.

 

I didn't find any kind of oil leak and I have tried both recirculating and non and get the smell on the first 3 settings of the blower. The highest setting no smell at all. That's what is confusing me. This is a work truck and my boss told me that it doesn't effect the operation of the truck so don't worry about it so I can't bring it into a shop. It is annoying that I have to use it full blast or I end up sucking in what ever that smell is.

 

High speed bypasses the resistor. Have you verified you have no debris inside the blower box where the resistor lives?

 

I have not but thank you for clearing up the reason Highspeed doesn't give me that smell. it will narrow down my search.

 

When you have the 'smell' try to feel if the wiring at the resistor is getting hot or see melting wires.

Loose electrical connections there would create more resistance and would make the wires overheat?

You could also try to test by running the resistor without having it installed (for a short time as it is intentionally designed to be installed into the airstream to help remove heat (resistor cooling))

Did you (or the boss) buy a cheap part online or from a discount auto parts? Maybe a defect?