Hello, for the last week I have been getting a burnt electrical smell from my heat/AC ducts after the truck sits for several hours. It does this for about 15-30 seconds and then dissipates. It does this even with the engine off and just the blower motor going. If the blower is off I can't smell anything. I have tried changing the resistor and the blower motor so that doesn't seem to be it. The old ones worked fine and didn't smell. The heater core is only 2 years old and it doesn't smell like antifreeze either. It's worse on the driver's side than the passenger side. I have owned the truck for over 10 years and have never experienced this, now it does it every day.