On the older model Danfoss compressor systems there are two fuses, there is a fuse on the Danfoss electrical module and a fuse or circuit breaker at the battery main buss. If the 15 amp fuse or breaker blows at the battery buss and the 15 amp fuse on the module does not, the problem is in the boat wiring not the refrigeration unit. When the module fuse blows 90% of the time the module is faulty. Before replacing the module the compressor needs to be checked with an ohm meter. If the compressor tests OK, I would contact Adler Barbour or Frigoboat as they both still sell those four pin modules. These companies I believe will also test your old unit to confirm if it is truly a failed unit. Adequate heat removal of the complete condensing unit is important, if the unit is in the engine room it must then draw its cooling air from a cooler area. Adler Barbour sells a duct kit for remote condenser air cooling or you can make your own.
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Richard Kollmann, Kollmann Marine Inc.
Installing of a small 12/24 DC volt icebox to refrigerator conversion unit is not a very difficult project, as long as the person attempting the project has basic mechanical skills. Larger refrigerator conversion units with holding plates do require a much higher skill level. The four leading companies that sell the smaller systems do provide good installation instructions. The installation of a small pre charged air cooled ice box conversion unit consists of the following tasks: • Locating a suitable location for the condensing unit where it’s cooling air will only pass through the area ounce. • Drilling a hole through the insulated box in the correct location for the two refrigerant lines to fit through. • Use template to locate holes for mounting evaporator. • Running the evaporator tubing through the box and connecting it to the condensing unit. If there is any excess tubing it is coiled up near the condensing unit. • The thermostat is located in the ice box with its wires run to the condensing unit. • These units must be powered direct from the DC plus and minus busses. A fuse and switch at the buss is required or a circuit breaker to protect the wiring. Remember that 12 volt refrigeration requires added battery and alternator capacity. The most critical decision you will make is selecting the correct unit for your needs. I recommend you watch the slide show on my web site.
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Richard Kollmann, Kollmann Marine Inc.
I don’t know if I would convert an existing boat ice box to a Peltier 12 volt cooler or not, it would depend on my use of the boat and the energy needed to operate it. Before making a decision between a compressor driven and thermoelectric refrigeration it is best to consider the advantages and disadvantages of the Peltier units. Advantages of Peltier units: In a normal ice box conversion a thermoelectric unit has only one moving part the exterior fan. They do not use unfriendly refrigerants. They are maintenance free except for the fan. They can operate in any orientation and do no make noise or vibrate. They have the ability to heat and cool. Disadvantages of Peltier units Thermoelectric units can only reduce the temperature by 40 degrees F. below ambient. They appear to consume three times the energy to produce the same cooling effect of a compressor driven system. I did a web search to see if there was any actual data on thermoelectric units in boats. There are several write ups on home made systems but no actual performance information. This is an opinion taken from a web search of, Peltier 12 Volt Refrigeration. For a 5 cubic feet Ice box the Peltier (36 watts) shall run 24 hours /days. The inside temperature will be -40 deg. F from outside (ideal conditions) So under strong sun when the inside of the boat reach 90 f you will get not less than 50 f inside (based on a continuous duty) When the engine is running same temperature and even higher will be reach close to ice box. But the real killer is when you get the box to a suitable temperature. On a refrigeration system, you simply shut off the compressor and let the insulation keep the box cold for a while. With a Peltier cooler, you have a big heat sink on the inside connected to a big heat sink on the outside with only a fraction of an inch of silicon in between. When it is not making cold, the Peltier junction allows a lot of heat to pass through!
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Richard Kollmann, Kollmann Marine Inc.
There have been several changes over the years in the Danfoss compressors and their electronic controls, so when asking for help always report the compressor model. A large portion of my new book is dedicated to the Danfoss systems old and the new BD35 and BD50 models. I am assuming your AB was built prior to 1995 so I will list the no start troubleshooting procedures for the BD 2.5 and BD 3 compressors. • Danfoss BD 2.5 and BD 3 compressors failure to start. Repeated failure of start and a audible cycle beep is caused by a program in the electronic unit. It is programmed to stop the compressor if; #1. The voltage is below 11.5 volts during start . Check batteries for charge. Check for a resistance connection. The best and quickest way to do this is run a temporary set of wires from a fully charged battery to the compressor electrical module. The wire size and polarity is important. #2. The fan or if water-cooled, the pump relay is drawing more than one amp.. To check disconnect one of the wires to fan. If the compressor starts OK replace fan. #3. The compressor is going bad and drawing more than 7 1/2 amps. To check install an ammeter in the power wire to the refrigeration unit. It should draw 5 to 6 amps when running, if more than 7 amps, the compressor is about to fail. To do this test the unit must be running. It is sometimes possible with a failed compressor to see a quick movement of the ammeter to 10 amps. or higher. The best test to determine condition of the compressor field windings is to check their resistance with an ohmmeter, See Drawing. #4 It is a good idea to eliminate the thermostat as a cause while checking the system. To eliminate the thermostat and its wiring disconnect its wires from the electrical module. Place a place a jumper wire across the module thermostat terminals. #4. If the above checks do not determine the cause the electrical module is defective. WARNING, do not install a new module on a compressor that test bad with the ohm meter.
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Richard Kollmann, Kollmann Marine Inc.
A ten year old Adler Barbour cold machine would have a Danfoss BD 2.5 compressor. Is this the compressor model that you have? When you say a thin cold plate I assume you mean an aluminum evaporator and not a plate with solution in it. When one of these air cooled units takes longer to cool, the first thing to check is the air flow across the condenser. Was it cleaned and performance rechecked before adding refrigerant? The AB units about ten years ago had the fan in front of the condenser and in order to vacuum the dirt out of the coil the fan must be removed. The electronic module that controls and protects the compressor will stop the compressor if there is an overload. Poor air flow through the condenser or a refrigerant overcharge will cause an overload and stop the compressor. It is also possible that low voltage or a faulty fan will keep the compressor from running. Here are my concerns: ¾ of a pound of refrigerant is too much for that system. Why did the system need refrigerant and was the leak found and repaired? If the compressor is a BD2.5 adding 134a refrigerant to it was a mistake. Refrigerant 134a is the correct refrigerant for the BD 3, BD 35 and BD 50. Recommended Corrective Action If the compressor is a model BD 2.5, have the refrigerant removed, evacuated and re-serviced with Freon R12 and no substitutes. If the compressor is a BD 3 and the condenser is clean, reduce the refrigerant charge to the correct value. The problem you are describing is a common occurrence today in boat refrigeration as the repairmen are not trained in these types of problems. See the item on my web site forum on; Save from $50 to $2000 on refrigeration repairs. As you will see from my answers on your forum this week I am not trying to push my 12/24 Volt Refrigeration Manual, but in your case I am sure it might have saved you at least five times the book’s cost.
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Richard Kollmann, Kollmann Marine Inc.
Moisture on the outside of a refrigerator indicates the insulation is poor. Moisture inside a refrigerator indicates moist air is infiltrating into the box. Any time an object is ten degrees colder than the air, moisture will collect on the object. Moisture always collects on the refrigerant evaporator and forms frost in a refrigerator. When the thermostat is set for a high temperature cooler instead of a lower temperature refrigeration, frost will not build up on the evaporator, instead it will melt and keep the refrigerator wet inside. Refrigerators are dry inside, not wet, until defrosted. Even self-defrosting refrigerators are dry inside because they capture the moisture and drain it away. Once I found moisture leaking into a refrigerator on a 41 Morgan OI when it rained. Moisture is also removed from the products placed in the box but it again shows up as frost on the evaporator and not as a wet liquid. If moisture in its liquid form is not leaking into the box then the door or lid seal must be leaking air into the box. To test the firmness of a seal’s contact, the door can be closed on a narrow ribbon. If there is no resistance when the ribbon is pulled out, that area of the seal is leaking.
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