'07 Lariat with auto climate. My old '04 XLT never had this issue, but I had noticed with the past few months a rare ( lately occasional ) dust/musty like scent to the air. I cleaned my vents out and it never stopped the issue. This occurs out of nowhere, basically whenever it wants to it seems, hot air or cold, a/c and off a/c. What in earth could it be? It sometimes gets so musty smelling I need to put the window down until it runs cleaner smelling air after a few minutes.

 

DarrenWS6,

This happens every once in a while to me. It has always been a dead mouse somewhere in the ventilation system. Same deal, musty odor that eventually goes away when his little carcass dries up. I don't tear things apart to find it.

 

A Mouse!?i think i would tear my truck apart to find that

My truck has that smell when ever i have been using the heat for a while then put on the a/c and the same the other way around. Only happens to me twice a year so i wasnt to worried about it.

Darren does your truck have a cabin air filter? Mabey if it is realy dirty when you hit a bump some of that dirt comes loose and blows through the HVAC sytem. Other then that i can't think of a reason. Invest in some little pine trees to hang here and there, you'll be fine

 

I didn't think these trucks had cabin air filters? Not even on the 97/03 gens. If this teuck might have one then I better find out. Out to the owners manual I go.

 

The smell usually comes from between the air intake on the cowl and the heater core(gets wet and mildew forms). Get the fan going on hi and spray short shots of Lysol in the air intake, while someone works the blend door thru all the positions a few times. Done this over the years and worked well. I just use the ordinary Lysol, not one of the new fancy new types.

 

check to make sure the ac pan drain isn't plugged.....

 

I dont know if they have cabin air filters, i did see a thread on installing a filter kit on a 2004-up truck so i wasnt sure, i'm pretty sure my 01 does'nt.