As they operate, window unit air conditioners will emit water. This is a result of condensation as the condenser lowers the temperature of the air being circulated through the unit. Some units include catch basins to capture the moisture and channel it into a tube for removal outside the home, but other units simply provide a drain plug which allows the moisture to drain out of the unit toward the rear.
The problem, where your homeowners insurance is concerned, is that properly mounted window units drain outside of the home, generally into a pipe or tube leading down to ground level. If your air conditioner does not have suck a drain in place, your claim will mostly likely be denied on the grounds that you have failed to provide proper maintenance or that the unit was improperly installed.
The next question is whether the mold occurred inside the home or on an outside wall. If the damage is on an outside wall, the mold can probably be cleaned up easily using readily available cleaning materials. If the mold is inside the wall, then the unit is either not draining properly or installed so that the outside edge of the unit is tilted upward, channeling the drainage into the home. Similarly, for the mold to cause extensive damage, the condition will have had to exist for an extended period of time.
With these above factors taken into consideration, it is unlikely that your insurance policy will pay for mold removal. Many homeowners policy exclude damage caused by mold for any reason, but in the situation described, even if mold damage is part of the policy's coverage, you would be denied the claim because of problems with maintenance or installation. Your best solution is to avoid filing a claim, perform the repairs out of pocket, and have the window unit inspected or adjusted so that further damage does not occur.