Preventing Musty Marine Air Conditioning Odours
The short answer
Run the fan alone for ten minutes after cooling, so the coil dries before shutdown. Then wash the filter, clean the drip tray and flush the condensate drain. The smell is biological, it lives in standing water in the tray, and drying the coil is what prevents it recurring.
Preventing Musty Boat AC Odours — Requirements and Limitations
Turn the fan on with the compressor off. If the smell is strongest in the first thirty seconds and then fades, it is sitting in the tray or the duct rather than in the boat, which is good news — all three sources are owner-serviceable in an afternoon.
A rotten-egg smell rather than mustiness is different: that is anaerobic growth in a seawater line left standing, and the fix is flushing the loop.
Related Sizing, Installation and Service Guides
Each of these answers a different part of the same problem.
- the full diagnostic pathin order, with the ranked causes
- flushing the drainthe same slime, dealt with properly
- cleaning the air sidefilter, coil and ducting
- keeping the cabin drythe underlying humidity problem