I own 2004 ford escape xlt. When I turn on the A/C, there is a strong musty smell that I can't seem to get out

sounds like your cab air filter needs to be changed

It has nothing to do with the cabin air filter here is a prime example of people not knowing what they are talking about on here. Its the lack of draining as was explained from your A/C . Ford does have another fix and that is a blower that will help by blowing air to keep that area dry because sometime they just don't drain correctly and some water or moisture is always in there so the blow will run when ever the A/C has been on so mention this to your Ford dealer.

try changing your cabin filter (not the air filter on the motor)and there are different sprays on the market made to take smell out of the ducting if there's any mould or whatever in the vents. most placesthat carry care cleaning products will have it.

Its a result of the condensation from your A/C unit that heats up in the summer time. It usually goes away as you run your A/C. There are deodorizers that can be puchased at your local Ford dealer.

The Air conditioner removes water from the air as it works---that water accumulatesand drips out under the car--chances are if there are no drips as it is running--the drain is clogged and the water gets stale and stinky. Clean the drain so that it allows the water to drip. if that is it--give it some time to dry out--maybe spray some vinegar into the drain if you can,--or weak bleach to kill the fungus. got to get under the car to do this properly--put it on a lift and do it safely

Replace the cabin air filter. You should be able to pick on up at your local auto parts store. They're relatively inexpensive, too. Good luck!

you might need to change your cabin/air filter

take it to the dealership and they should fix it for a nominal charge