Musty smell when a/c or heat turned on. How do I get rid of?

you need to claim a total loss on your insurance,you will never get rid of all the mold unless you take EVERYTHING OUT OF THE CAR

Check Under wiper rod cover near windsheild where Heather take is air or pollen particule filter

the drain plugs are located under the floor mats in the floor pan . If you look from underneath you will see the round plugs .If the carpets have been wet that bad then you will never get rid of the musty ( fungus) smell . consider new floor mats

Have your AC cooling coil (evaporator) washed and cleaned.

Most common cause is water sitting in the bottom of the a/c heater box. Make sure the outside drain is open. There are spray products for using on the vents.

Many times small pieces of leaves and other organic stuff can get lodged in the evaporator core,making a musty stink.You will have to clean and disinfect the evaporator core to get rid of the smell.See if you can find a kit for this at a good parts store(like NAPA or Carquest)

I would try spraying fabreeze in the vents with it turned off.

There are none on the 2006. There might be some moisture that entered the carpet in the vehicle at some time or another and caused a moldy or musty smell. There are several different air fresheners that can be added to the interior under the seat and in the carpets to help make is smell better.

The drain should go through on the passenger side under the dash....you might need to replace your cabin air filter.

Do you leave your climate control in the Auto position. This is bad. What happens is the evaporator which is located in the vents never dries out and you begin to grow mold. Does it smell musty, locker room type smell.
Also since it came out the heat vent it could also be a leaking heater core. Check you coolant level and reservior. If low this is an indication heater core is leaking. It may not of leaked enough to tell but usually these are the only reason the vents would smell unless a rodent ended up there and died.