I have been through this drill and I would be very circumspect with the use of bleach on your A/C heat exchanger
. Moreover, I find it surprising that there is not a filter on your return air at or before the heat exchanger
N'any case I suggest you start your cleaning
by using a shop-vac to suction out the heat exchanger, being careful to avoid bending the vanes. Lowes/Home Depot sell attachment kits for shop vac's with a reducer cone that allows one to use very small tools (included in the kit) to suction out small spaces and tight areas (compute key-boards/vnets/fans and the like) that will aid in cleaning
. Then spray the Heat Exchanger with a surfectant agent such a Greased Lightening or Roll Off to break down the remaining dirt and debris. After that has "soaked in" for awhile, use a spray bottle with clear water to "rinse" the heat exchanger, periodically suctioning the run-off out of the condensate pan with a tube connected to the cone reducer on your shop vac (which will also help clear the condensate pan). Once that's done, spray with an mildecide. Assuming you can get access to the fan assembly, one frequently finds that condensate water that pools at the bottom of the squirel cage has also allowed mold/mildew to grow and this needs be cleaned out in a manner similar to the above although it's awkward. Having done all of the foregoing, activate your fan (but not cooling) and spray some mildecide into the return air intake--to treat the squirel cage--and let that run for awhile to dry the machine out.
While the foregoing will treat the A/C unit itself, if you have a duct system to distribute the cooled/heated air, the ducts may also have mold
growing in the dust that invariably coats the inside faces of the tubes. If one cannot get access to run wads of cleaning cloths (Swiffer Duster pads work well) through the tubes, the other alternative is to rent an Ozone Generator
from some place like ServPro that does water damage restoration
and set that up so that it discharges into your return air intake. With the A/C unit running (fan only if possible), you can circulate Ozone through the system for a few hours which will kill off most of the remaining mold/mildew in the system. Do not stay aboard the yacht during this process and thoroughly air the boat out before resuming normal use as Ozone has horrible effects on one's lungs.
Having done all of the foregoing, your system should be pretty well cleaned out and odor
free. To avoid prblems in the future, you need to add a filter to the return air intake at the face of the heat exchanger. One of the most effective is an adaptation of a stove-top vent fan filter. At Lowes/Home Depot you can find these and the best are those comprised of two layers of fine metal mesh with a layer of fine screening impregnated with activated charcoal in the middle. These can be cut to size and the edges secured with a fold of duct-tape. If your heat exchanger is not fitted with clips to hold a filter in place, you can secure the screen
with lengths of bamboo skewers from the supermarket clipped to length and slipped over the screening and under the edges of the heat exchanger. (On our boat I have also added a common household paper mesh filter on the outside face of the metal screen
mesh but that's not entirely necessary.) Routne cleaning of the filter screens will be wise.
The foregoing has worked for us and could prove helpful for you as well.