There are a couple of things that you can do. First, make sure the rubber drain hose at the base of the firewall (on the engine side) is open. It will appear to be a closed-end rubber tube, but it has a slit in it to allow a slow drainage of moisture condensed by the a/c. Squeeze the end of the tube to make sure it is open enough to allow a slow drainage. This is often down where road grime, mud and such will “glue” it closed.
Second, run your a/c compressor in all seasons. When you turn the defroster on, the a/c compressor should run to de-humidify air blown on the inside of the windshield. This flushes some clean condensation through the system and helps flush out old, stale water than may have accumulated in low spots. This is also good because it circulates oil through the compressor lines to help keep seals from drying out or leaking.
Third, turn the a/c off before shutting the car down for the day. Allow the ventilation fan to run a bit as you pull onto your street to help blow moist air from the vent system.
Modern a/c systems are properly designed, but manufacturing inconsistencies may provide “low” spots that do not drain completely. This is the source of the mold that causes the odor. If the car is still under warranty, have it checked to make sure all hoses and vents are working properly. If you have a garage, park the car with the windows down at night and allow the car to air out to help evaporate moisture trapped in the vents.
I would use deodorants only as a last resort. They are only temporary fixes. Bleach will kill mold, but it also is temporary. You need to attach the problem, not the symptom.