Ford F150 - air conditioning

I have a 2002 supercrew with a 4.6L. My complaint is that whenever I use my A/C it smells bad, almost like mold. My question is, how can I fix this?

Do you turn the a/c off when you shut the truck off?
It is a good rule of thumb to shut the a/c off a minute or two before you shut the engine off to clear it of any "cold" air left in the system. The problem is that the "cold" air that has not blown out will condensate in the vents and will have a musty smell over time. You can also try to run just fresh air through the vents to clean them out a bit.

Ha, walks like a duck, quacks like a duck...

It IS mold. I'm guessing your home turf runs predominantly over 50% humidity. Your A/C squeezes theat moisture out of the air and it has to go somewhere. There is a drain pan under the heat exchanger and a drain hose. I have no idea where that one runs, but I'll betcha its mostly blocked. Find a way into that drain pan and pour a commercial mold/mildew product into it. Hope it drains. last time I had this problem (in a Toyota), I reamed it out with one of those toy-sized tape measures. It was just small, rigid, and flexible to make it all the way.

On hot humid days, (when the A/C is really dripping under the truck), I not only turn off the A/C but I also turn the heat up to maximum so it blows hot air for a few minutes before I shut the truck off.. This helps dry out the plenum so there are no puddles to grow mold.

I don't know if people who smoke use the truck, but if they do, don't use MAX/AC while smoking.. In the MAX position the fresh outside air is shut off and the smokey cab air is constantly recirculated over the evaporator.. This is also a great way to get a smelly AC system.

It could just be old stale water laying in the pan as well. I would guess that u use MAX air alot. This recirculates the inside air for maximum efficiency in cooling.

It is a good idea to use AC only or vent every now and then to dry thing s out.

Even on vent the AC runs to take the humidity out of the air. IT is a good feature on our trucks.