After letting the truck sit for a day or two and then taking a drive, there is a mildew smell coming the ventelation system. It doesn't matter whether you use the AC or heater. It happens for the first 3-4 minutes and then it goes away. Is there any way getting rid of this smell?

1999 F250 lightduty S/C XLT 4x4
5.4L, 3.73, 4R100 trans.

 

It might not be actually coming from inside the ducting. Try peeling back your carpeting and see if the padding is wet. That is the most probable cause of the mildew smell. Water leaks could be from the windshield, door seal, a rubber grommet that popped out of the fire wall, even a leaking heater core or clogged drain for your A/C.

You smell it when turning your A/C or heater on because it draws the air from under the dash and blows it out the vents (on every setting except the A/C on normal or just the vent. These 2 settings draw fresh outside air).

If the carpet is not wet, I have no idea.

Hope this helps

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Boss™

Just Ordered 2001 F-150 Lariat Wht/Slvr medium graphite leather, 4x4, SC, SB, SS, 99L 5.4L, 44E tran, 7700# payload, Class III Tow, 3.73LS, Skids, Capts chairs, 4W disc ABS, shift-on-fly, keyless, HD everything

Planned Mods:
Westin Chromed Stainless Nerf Bars, ARE LS II bed cover, Bedrug™, Gibson Swept Side Cat Back, K&N filter w/airbox mods, Headman headers, Superchip, 3" body lift with at least 33's, alarm/pager/auto start system, stereo system

 

Try turning the selector switch to vent and blower on high for a few seconds prior to shut down.

 

After you make sure you don't have a water leak try this, it's been posted several times over the last 2 years.
Turn on the A/C with the fan on high and make sure it's NOT on MAX A/C. Get a can of Lysol and spray it in the vent just in front of the windshield. When you can smell the Lysol in the cab turn everything off and let it sit for a few hours, that should kill the mold that's growing in the ducts.
Afterward use Fuller's suggestion before you shut the truck down every time you use the A/C.

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1999 Lariat Super Cab, S.B. 5.4L, 3.55 LS
and everything but the leaky slider window.
Bright red w/ gold 2-tone, Leather Captain's Chairs
Mods: Duraliner bedliner, Bugflector II, Hide-a-hooks.
& a leeetle chrome tip on the exhaust.

 

I think its the same problem as the HVAC in all four Tauruses we have had. The Ford guys have said there is a spot just inside the intake vent on the passenger side that retains moisture. It molds/mildews and causes the smell. We occasionally take a can of lysol and spray into the intake with the system blowing on high. Works well, but you have to do it every once in a while. I don't have the problem with my Truck, even in very hot and humid Houston.

 

Thanks to for the Lysol tip. I'll definitely give it a try. I hope it works, because the smell is annoying. It only seems to happen when it's humid or after it rains. I recently installed some B-Quiet sound deading material and there was no indication of leaking water anywhere, and the carpet was fine. Again, thanks.

Bill

 

To amplify Dewayne Fuller's suggestion -- don't park your truck with the heater control in the 'Off' position. When in any position other than Off or Max, the truck can 'breathe' -- from exterior wind pressue -- and may help evaporate any moisture trapped in the heater from its prior use.

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Y2K™

Toreador Red, Keyless XLT SC SB 5.4L E4x4 4wDisc/ABS, 3.73LS, Skid, HD 7700# Towing, LT-245's on Chrome, Tube-Steps, Captain's, 6CD, Tonneau, named: "Nick"