Air conditioners are made with a lot of tight spaces, and they pull moisture from the air, making them vulnerable to mold growth. With some easy cleaning and general maintenance, you can take care of most mold problems in your AC unit.
Chemicals that Clean Mold
There are a wide variety of things used to treat mold. Fungicides are potent to serious mold growth, but common household disinfectants can do the trick a lot of the time as well. One of the cheapest and easiest solutions is a mixture of vinegar and water.
Spraying the AC
The short answer to whether or not you can spray your air conditioner to kill mold is: Yes. The long answer is a bit more complicated. It depends on what you use. Harsh chemicals in fungicides can harm its delicate evaporator and condenser coils. A mix of one cup of vinegar in a spray bottle filled with water makes for a good mold-killing solution that won't ruin your AC.
Replace the filter after treating a mold problem in your air conditioning. Mold spores in the filter would just cycle back through the system otherwise. Regular cleaning or replacing the AC filter will help prevent mold from growing there in the first place.