I have a 2003 XL I6. In January, I started noticing the smell of exhaust eminating from the engine compartment, and into the cabin when the heat or AC was on. It smells as if I am following a large city bus with my windows down. A mechanic had it twice, for a solid week each time. Told me it was...

I suspect my wife is turning off the truck without blowing fresh air through the condenser coils... We took the truck out last night, and we got a nice musty odor coming through the vents as we pulled out of the garage. She said "it's been doing that lately." I looked down at the HVAC...