MARINE PRODUCT TROUBLESHOOTING

Mermaid Manufacturing strives to produce the finest products on the market and works hard to meet or exceed the demands of today’s customers.  With this in mind, Mermaid has created this troubleshooting section to aid you, or your customer, with any issue that may arise.  Should something occur that is not included here, please let our staff know.  We will do our best to include the issue for our current and future customers.

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COMMON TROUBLESHOOTING ISSUES

HIGH PRESSURE SWITCH ACTIVATES IN THE HEAT MODE

PROBLEM: During the operation of your marine air conditioner in the HEAT mode, the RESET (high pressure) switch activates.

When the high pressure switch activates in the HEAT mode the evaporator is not being properly relieved of heat. This is usually due to air flow restrictions. Remove the restriction.

  • Dirty air filter
  • Blocked return air
  • Return air grill smaller than specified physical size
  • Closed or insufficient number of supply air grilles
  • Duct runs too long, too many turns or kinked creating a heat back up on theevaporator

NOTE: Another commonality of this behavior is the operation of the HEAT mode when not called for.  “Testing” your HEAT mode for any short degree of time during warm temperatures will result in high pressures on your system thus resulting in the RESET button activating.

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CONDENSATION PAN OVERFLOWS

PROBLEM: Your marine air conditioners condensation pan is overflowing.

Drain pan nipple on pan clogged. Clean nipple.

Drain hose clogged, misaligned or kinked. Fix and/or clear hose.

Air conditioner not properly elevated to drain water to drain pan nipple. Check unit mounting to insure water will flow to nipple.

If a Mermaid Condensator is being used, ensure that the filter is clean.  If not, clean filter and check flow of water through Condensator.  Refer to the Mermaid on-line Condensator instructions for further assistance.

As a last resort, we do manufacture a stainless steel oversized drip tray that the ENTIRE A/C unit fits into.  This is commonly used in sailboat applications where the “listing” of the boat causes the condensate to spill over the side of the condensate tray on the AC base.  Let us know if we can assist you with the oversized tray.

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REVERSE CYCLE UNIT – NO HEAT

PROBLEM: While attempting to operate your marine air conditioner in the HEAT mode and not heat is discovered.

Reversing valve sticking. Tap lightly with rubber handled screw driver. Tap either end while the unit is running.  Listen for a “hiss” noise once completed.

Reversing valve solenoid loose or wire off. Tighten nut on solenoid and/or secure wire.

Loose wire or faulty reversing valve relay in electrical box. Remove all power to boat before opening electrical box.  Once power is OFF and the cover is removed from the black or gray electrical box, check for any loose wires that may have come off.

If none of the above work, contact the Mermaid Factory

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HIGH PRESSURE SWITCH ACTIVATES IN COOL MODE

PROBLEM: While your marine air conditioner is running in the COOL mode, your RESET (high pressure) switch trips off.

Only a lack of cooling water will activate the high pressure switch when the air conditioner is operated in the COOL mode.   The high pressure reset switch is connected to the refrigerant line leading from the air conditioners compressor.  The activation of this switch is indicative of lack of water flow.  This is the ONLY thing to cause the reset button to “trip.”  Should this device activate, it is important to check the flow of water through the unit.

Start with the sea water pump to ensure it did not lose prime.  Check for kinked water hoses or blocked lines including the sea water strainer.

Lastly, ensure the air conditioners water coil is not full of debris.  Even the cleanest of strainers can still allow salt, sand, or other debris to accumulate in the air conditioners condensing coil.  This will inhibit heat transfer and cause the air conditioner to lose cooling capacity and run warmer – eventually causing the pressures to exceed the high pressure reset button setting of 375psi.   A fresh water coil flush may be necessary, if it is deemed necessary.  Simply flush the air conditioners water coil and lines with garden hose pressure water.  The pumps in the marine industry are volume pumps, not pressure pumps.  The flow of water through a garden hose is substantially higher and can flush the debris that may have accumulated inside the water coil.  It is recommended to do this procedure at least once or twice a year.  The frequency of this will depend on the caliber of water your vessel is in.

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AIR CONDITIONERS EVAPORATOR IS FREEZING

PROBLEM: While the marine air conditioner is running, the evaporator is freezing.  This device looks like a radiator for a car.

Supply air vents closed or insufficient number of vents. Open and/or add additional vents.

Fan not running or intermittent.

Return air blocked. Clean air filter and/or remove any blockage.

Thermostat set too low and is not allowing unit to cycle and remove icing.  Set thermostat at a higher setting.

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.

Low freon due to leak. Unit will require professional service.

NOTE: The most common of this problem is insufficient ventilation coming off the unit.  Additional vents are needed or “cleaning” the existing ducting scheme to ensure better airflow off the system.  Remember, the more vents the better on ANY unit.  Each unit has minumum vent requirements, review your product under Marine Air Conditioners if needed.

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ELECTRIC HEAT UNIT – NO HEAT – FAN RUNS

PROBLEM: While operating your marine air conditioner with Electric Heat versus the Reverse Cycle and no heat is discovered.

NOTE: Remember that on electric heat models the pump nor the compressor will run. Only the fan and the heater coil are activated.

Check for loose or disconnected wires in the electrical box. Before opening electrical box remove all 115 vac power from boat.  Contact Mermaid Marine Air if you need additional technical support.

If wiring is deemed good, problem will either be a faulty thermal safety fuse or a faulty heater coil. Usually the thermal fuse is the problem. To replace either item remove the metal cover from around the evaporator by removing two screws on each side and two bracket screws on the top of the evaporator. The evaporator cover will pull straight up exposing the coil and fuse. Both items can be checked with a continuity checker. Replace the faulty item and reposition the cover and replace the retaining screws.

Contact the Mermaid factory for additional assistance if needed.

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NO WATER OUT OF THE UNIT

PROBLEM: Your marine air conditioner is not having water show in the “water out” thru-hull.

Put thermostat in OFF position.

Check that sea cock is open. If closed, open and prime pump.

Check raw water strainer. If dirty, clean and prime pump.

Check that pump is running. If pump is faulty, replace and prime.

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 are removed from the condensing coil.  These were put on after the unit was water tested at the factory.

If still no water, do a fresh water garden hose flush of the system to ensure nothing is blocked inside the coil.

If further assistance is needed, don’t hesitate to contact the Mermaid factory.

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COMPRESSOR RUNS – FAN DOES NOT

PROBLEM: When using your thermostat, the compressor turns on, however, your fan does not.

Place thermostat in the OFF position. Use a short jumper wire, connect the  “RED” wire to the “GREEN” wire on the side of the electrical control box near your unit.  If this is not accessible, remove the face of the thermostat exposing all the thermostat wires.  Remove the single RED wire and single GREEN wire.  Twist these two wires together independently.  If fan comes on, thermostat is faulty.

If fan does not come on when jumper is applied, it is most likely a faulty fan relay inside the electrical box or the external fan capacitor on the larger model Mermaid units.. Replacement of the fan relay or external capcitor may be necessary. Before opening the electrical box all 115 power must be removed from the boat.   It is recommended to call the factory for further technical support.

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CIRCUIT BREAKER WILL NOT STAY ON

PROBLEM: Your marine air conditioners circuit breaker continues to “trip off.”

Shorted wire.  Check for loose or disconnected wires.  Reconnect or replace as necessary.

Pump internally shorted. Remove pump power from electrical box and start the unit. If circuit does not trip, replace pump.

Check circuit breaker for proper operation. If faulty, replace circuit breaker.

Compressor shorted internally. Compressor must be replaced professionally.

Seek factory assistance if needed.

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THERMOSTAT IN COOL – NO OPERATION

PROBLEM: Thermostat in located in the “COOL” position and the marine air conditioner is not turning on.

Make sure that Thermostat delay period has expired. Delay may be as long as 5 minutes. Also, if applicable, check the thermostat batteries located in the front of the display. On our newer units the batteries are inside the face plate.

Check SET temperature to make sure temperature is set below cabin temperature.

Note: If cabin temperature is displayed as “HI” or “OL” this indicates cabin temperature is over 99 degrees. This does not effect unit operation and the normal temperature display will appear once the cabin temperature falls below 100 degrees. “HI” = High Temperature, “OL” = Out of Limit.

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.

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.

If main breaker is operational, using an AC voltmeter, check for 115 vac power at the unit electrical box.

WARNING
ALWAYS USE EXTREME CARE WHEN CHECKING 115 VAC POWER. CONTACT WITH 115 VAC POWER CAN CAUSE SERIOUS INJURY OR DEATH.

If power is not present, check 115 power leads on unit electrical box WHITE terminal block for polarity, tightness and for signs of discoloration. If power is still not present, check the air conditioner circuit breaker in the Main Circuit Breaker Panel for lose connections (SEE ABOVE WARNING).

If 115 vac power was present at the WHITE terminal block, using your AC voltmeter, check for 24 vac on the “RED” wire attached to the BLACK terminal board located directly above the WHITE terminal block on the side of the electrical box. You should get a reading by placing one voltmeter lead on the “RED” wire and the other on any other color thermostat lead wires.

If 24 vac is present and all of the above checks and procedures are positive, most likely the thermostat is faulty or a wire has loosened inside the electrical box. To check the thermostat, take a 5 or 6 inch piece of insulated wire, strip the insulation back about 1/8 inch on each end and use it to short the “RED” wire to the “BLACK” wire on the BLACK terminal board located on the side of the electrical box. If the unit immediately comes on, the thermostat is faulty and needs replacing. If the unit does not operate, the problem is in the electrical box.

If 24 vac was not present in step 3 above, most likely the transformer inside the electrical box is faulty or a wire has loosened inside the box.

Note: Once a problem has been isolated to the internal portion of the electrical box the box must now be opened. Before preceding further, you must disconnect all 115 vac electrical power to the boat. (SEE WARNING BELOW)

WARNING
IF ALL 115 VAC POWER IS NOT DISCONNECTED FROM THE BOAT YOU MAY INCUR ELECTRICAL SHOCK WHICH CAN CAUSE SERIOUS INJURY OR DEATH.

After you have removed all 115 vac electrical power, the electrical box cover may be removed by removing the three retaining screws on each side of the box. Once the screws are removed the cover will slide off the box.

Closely check the box for loose or disconnected wires. If all wiring is tight and in place, replace the transformer. A new transformer maybe purchased from your nearest Mermaid dealer, refrigeration supply store or directly from the Mermaid factory.

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THERMOSTAT IN COOL – FAN WORKS – COMPRESSOR DOES NOT

PROBLEM: The thermostat is in the COOL position with only the fan operable on the unit.  The compressor is not running.

Place thermostat in the OFF position. Locate the HIGH PRESSURE switch mounted on the top of the air conditioner unit. On units more than three years old, check if metal tab on the RESET button is extended. If tab is extended push it in. On our newer units, push the red tab on the green switch with the RESET sticker located on the body of the device. These switches shut power off to the compressor (and sea water pump on the newer units) when cooling water is insufficient to make the required heat exchange as described in Theory Of Operation in your manual. 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.

If water pump is operational and HIGH PRESSURE switch has not activated, perform thermostat jumper test described in your manual.  If you do not have your manual, remove the faceplate of the thermostat exposing the Red, Green, Black and White wires.  You will notice there is also a Red jumper wire in place.  Be sure your circuit breaker is in the OFF position at this time.  Once the breaker is OFF, remove the single Red wire, the single Black wire, and the single Green wire.  Leave the Red jumper wire in place.  Manually twist together the Red, Green, and Black wires.  Once completed, turn the units circuit breaker back to the ON position.  The entire system should engage in the COOL mode at this time.   If unit operates, replace thermostat batteries and/or thermostat.

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Installation, Service, and Warranty

We sell between 900-1200 marine A/C units to happy customers each year. Every new unit purchased from us comes with a 5 year warranty against material defects and workmanship. We believe in our manufacturing staff, so all repairs are done here on site. If you have any problem, just call us and we’ll explain how to arrange for service. We’ll even cover shipping costs for any units being serviced for the first 6 months after purchase. After that 6 month period, we’ll split the shipping costs with you.

You may choose to hire someone to install your unit at your own expense. However, more than half of our customers install these units themselves – the installation process is vey simple. We’ll send a detailed installation and operations manual with every unit (or you can reference our documentation page).

In order to make it even easier for you, we offer an installation kit that includes everything you need  to install your new Mermaid unit, except the water pump. This kit contains all the hoses, ducting, grills, and more!

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LOOKING FOR IMPORTANT DOCUMENTS?

Download all the documents you might need for our marine products, including schematics for all of our air conditioning units, as well as an installation guide and a full marine product catalog.

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