Don’t be embarrassed at all — marine AC controls are notoriously unintuitive, especially the older Westerbeke/Rotary Aire systems. Half of them feel like a 1997 microwave designed by sailors. Your system is almost certainly a reverse-cycle heat pump, meaning there usually is not a separate “heater” and “AC” switch — you toggle the operating mode on the thermostat/control panel. � westerbeke.com +1 Here’s the usual sequence on Rotary Aire controls: Turn the system ON Look for a button labeled: MODE COOL/HEAT or sometimes just a snowflake/sun icon Press MODE repeatedly until you see: ❄️ COOL or just “COOL” Lower the set temperature several degrees below cabin temp. Wait about 30–90 seconds. These systems intentionally delay compressor startup to protect the unit. � pdf.directindustry.com +1 A couple important clues: If the fan runs but the air is warm, it’s probably still in HEAT mode. If nothing happens immediately after switching modes, that’s normal. You should eventually hear: the seawater pump, then the compressor kick in, then cool air. On many older Rotary Aire panels: Up/down arrows change temp only MODE cycles: Cool Heat Auto Dehumidify/Fan If yours is the really old-school rotary-knob version: One knob = temperature One knob = fan speed One rotary selector = OFF / FAN / COOL / HEAT � Yachtaid Marine And one very boat-specific gotcha: If the seawater pump breaker got switched off during cleaning, the unit may refuse to cool. Check for an “A/C Pump” breaker on the electrical panel if you don’t hear water moving. You are very much not the first person to stand in a cabin angrily pressing random buttons while muttering “why is it still hot.”

Copy paste from the stupid robot. Maybe helps though