When I first turn on my defrost, I smell a stinky musty smell.

What can I do to fix this ?

 

Take your favorite scented room air freshener aerosol can, and while the heater is on full blast, spray a generous helping of it in the passenger side of the wiper cowl, where it's open. Should fix ya.

 

Thanks for the help, I appreciate it.

 

A musty smell is indicative of mildew...mildew needs moisture. The moisture may be coming from the moisture not getting out of the air conditioner drain (as you probably know the air conditioner runs when the defroster is on). I'd check the drains and make sure they aren't plugged with mud or that a furry animal has moved in (I've seen both cause it)....

 

What Neal said, except for the critter. Haven't seen that yet.

 

Yeah, sounds like a clogged drain. You can get to it by reaching under the fender liner on the passenger side. Not easy but doable. Feel the plastic housing around the condenser, follow the seem to the bottom and there is a very small opening they call a drain. Use a small wire to open, with a little luck it will start draining. If it stays open, it will rid itself of the smell.

 

Cool, didnt know that, thanks!

 

Now your kidding with me. You're probably the one I learned it from.

 

Use Lysol aerosol or one of the commercially available coil cleaners and antifungals. The coil cleaners will also improve the efficiency of your condenser.

 

When my other truck was at the dealer, they used airsept, some sort of anti mildew spray. Same smell hapened with my 350 and she's been out of warranty for 125,000 miles, so i took the glove box off, and took the 'door' off of where the heater core is and sprayed lysol all over it a couple times. Sealed it back up with rightstuff gasket maker, and haven't had a problem since...well, when it rains I get a wet hay smell, but that is understandable. If you use your a/c turn it to vent a little before you get to where its going to be parked so the evap can dry out, otherwise mildew will come back...

 

NAPA sells an AC deodorizer part number BK 7656000

LINK TO NAPA