Mermaid air conditioner troubleshooting

The table contains measures how to prevent damage to the air conditioner (regular preventive maintenance), diagnostics of the device, it also shows the main problems in the operation of the air conditioner, possible causes of malfunctions and ways how to fix them.

1. Standard 24v Thermostat In COOL Position - No Operation:a) Make sure that Thermostat delay period has expired. Delay may be as long as 5 minutes.
b) Check SET temperature to make sure temperature is set below cabin temperature.
c) Once you are satisfied that the delay period has expired, check that both boat main circuit breaker and air conditioner circuit breakers are in the ON position.
d) If both breakers are in the ON position, check to see if boat power source is present. If power source is present, turn on another boat 115 vac accessory to make sure main breaker is operational.
e) If main breaker is operational, using an AC voltmeter, check for 115 vac power at the unit electrical box.
2. Standard 24v Thermostat In COOL Position - Fan Runs - Compressor Does Not:a) Place thermostat in the OFF position. Locate the HIGH PRESSURE switch mounted on the top of the air conditioner unit. Check if the red button is active or extended. If the pin is extended, push it in. This switch shuts power off to the compressor when cooling water is insufficient to make the required heat exchange as described in Theory Of Operation above. Check water pump for prime and motor operation, check raw water strainer for clogging and hoses for kinks. Fix water problem and turn thermostat back on.
b) If water pump is operational and HIGH PRESSURE switch has not activated, perform thermostat jumper test described in paragraph 1h) above. If unit operates, replace thermostat batteries and/or thermostat.
3. Compressor Runs - Fan Does Not:a) Place thermostat in the OFF position. Use a shorting wire as described in paragraph Ih above, except this time short the "RED" wire to the "GREEN" wire. If fan comes on, thermostat is faulty.
b) If fan does not come on when jumper is applied, it is most likely a faulty fan relay inside the electrical box or an external fan capacitor. Replace the fan relay or capacitor with the recommended from the factory. Before opening the electrical box, all 115 (220) power must be removed from the boat.
4. No Water Out:a) Put thermostat in OFF position.
b) Check that sea cock is open. If closed, open and prime pump.
c) Check raw water strainer. If dirty, clean and prime pump.
d) Check that pump is running. If pump is faulty, replace and prime.
e) Check for any obstructions in the intake or strainer/water lines. Periodic growth of bamicles or accumulated debris may block the water intakes.
f) If this is a new installation, check to make sure that pump, water strainer and sea cock are all below sea level. Pump will not prime if any of these parts are above sea level. Also ensure the caps have been removed from the water (condensing) coil.
5. Evaporator Freezing:a) Supply air vents closed or insufficient number of vents. Open and/or add additional vents.
b) Fan not running or intermittent. See paragraph 3 above.
c) Return air blocked. Clean air filter and/or remove any blockage.
d) Thermostat set too low and is not allowing unit to cycle and remove icing. Set thermostat at a higher setting.
e) Thermostat improperly located in a position not giving “true” cabin temperature. Examples would be in a sunny spot near glass, or near the hatch. Relocate thermostat.
6. Condensation Pan Overflows:a) Drain pan nipple on pan clogged. Clean nipple.
b) Drain hose clogged, misaligned or kinked. Fix and/or clear hose.
c) Air conditioner not properly elevated to drain water to drain pan nipple. Check unit mounting to insure water will flow to nipple.
7. Circuit Breaker Will Not Stay On:a) Shorted wire. See the WARNING under paragraph li above regarding electrical service in and outside of the electrical box and at the circuit breaker. Check for loose or disconnected wires. Reconnect or replace as necessary.
b) Pump internally shorted. Remove pump power from electrical box and start the unit. If circuit does not trip, replace pump.
c) Check circuit breaker for proper operation. If faulty, replace circuit breaker.
d) Compressor shorted internally. Compressor must be replaced professionally.