12 Volt & 24 Volt DC Fridge Troubleshooting Frequently Asked Questions
Q Does the compressor run?
YES If the compressor is running the issue will be due to refrigerant, either a loss of refrigerant or a blockage. See our Checking Refrigerant Charge on R134A Systems to confirm.
NOTE: make sure you are 100% certain that the compressor is not running. The compressor is very quiet and often if the fan or sea water pump is running it can trick you into thinking the compressor is running. If you are in any doubt, disconnect the fan, or sea water pump so you can hear the compressor or feel it vibrating.
NO If the compressor is not running the problem is most likely to be electrical.
Check the breaker or fuse and using a multi meter confirm that you have either 12 or 24 volt at the terminals of the electrical box on the compressor and that the wiring is correct as per the wiring diagrams below:
Q If the compressor still does not run, have you checked or isolated the thermostat?
The thermostat is a switch and when the fridge needs to cool the thermostat circuit needs to be closed, which you can do with a simple bridging wire to link C & T. See video below on how to test the thermostat:
If the compressor starts once you link out the thermostat then it is the thermostat which is faulty and needs to be replaced. You can find replacement thermostats in our shop
Q If the compressor still does not run, have you thoroughly checked the electrical installation?
Use the Testing Electrical Installation manual to confirm the wiring circuit is good between the batteries and the electrical box. If your compressor is a Danfoss (Secop) BD35 or BD50 use a 12V LED to run a fault diagnostic see BD35 & BD50 Fault Diagnostics manual or our trouble shooting video below for details on how to run this test?
Q Does the fan run, but not the compressor? Or can you hear the compressor try to start and immediately stop again?
This issue is normally due to voltage drop. The electrical box is sensing enough voltage to start (so the fan or water pump will run). At the point the compressor tries to start the compressor will need up to 12A at 12V momentarily and if there is any resistance in the wiring circuit between the battery and the compressor you will get a voltage drop and the Amps required will not reach the compressor and it will fail to start. This cycle will go on and on indefinitely. If your compressor is a Danfoss (Secop) BD35 or BD50 use a 12V LED to run a fault diagnostic see BD35 & BD50 Fault Diagnostics manual or our trouble shooting video below for details on how to run this test?
TIP Sometimes you can over come this problem by starting the engine or putting the battery charger on to boost the volts of the batteries and help the compressor start.
Q Is the Thermostat set correctly?
Turn the thermostat to a colder setting.
Note that the thermostat on Vitrifrigo C85i and C115i models are located behind the salad bin at the base of the cabinet
Q Does the compressor run excessively with heavy frost or ice build up on the evaporator (ice box)?
Your fridge or freezer cabinet may need attention. If the cabinet is not completely air tight moisture in the air will freeze on to the evaporator plate causing it to ice up excessively. This in turn will insulate the plate and prevent the fridge from reaching the correct temperature. Thoroughly defrost the cabinet, check the door seals and check any other areas where air can get in to the cabinet (drains and where the pipes exit the box for example) – for further details see our Cabinet Check List
Q Does the compressor run excessively or continually with no significant build up of frost on the evaporator?
If the compressor is running excessively or continuously then it may a lack of refrigerant. With the compressor running, you can do check to see if there is refrigerant in the evaporator by licking your finger and touching the plate. Correctly charged your finger should stick to the plate all over – see Checking Refrigerant Charge on R134A Systems to confirm.
If the plate ices up erratically, working some of the time make sure you are 100% certain that the compressor is always running and you don’t have a power supply issue (normally voltage drop when the batteries are below 100% charge). If you are in any doubt, with the batteries fully charged, link out the thermostat and run the system for 20 minutes to confirm the plate ices all over. If it does use our Testing Electrical Installation manual to check the wiring.
Q Is the equipment correctly specified and installed?
You can use our system builder to confirm that you have the correct size evaporator installed.
If your fridge is too cold and you find that you are freezing your tomatoes and salads, assuming the plate has been specified correctly, the most likely cause of the problem will be the thermostat. There are three possible reasons:-
1. The thermostat is not set correctly
Adjust the thermostat down to its lowest setting and see if the temperature in the fridge rises accordingly. If there is no change in the temperature then check the probe or the thermostat is likely to be faulty.
2. The probe is not sensing correctly
If the fridge has a mechanical thermostat and an evaporator plate then you need to check that the very end of the capillary sensing probe is touching the plate. There is normally a clip or clamp to hold the probe in position. Confirm that the end of the probe is touching the evaporator. If it is not touching it will sense the temperature from the air in the box, not the plate and the evaporator plate will run too cold.
If the fridge has a digital thermostat the probe on the thermostat may be faulty. You can test this by measuring the resistance and comparing the reading to the table in the link below:
3. The thermostat is faulty
If you have checked steps 1 & 2 above then the thermostat is likely to be faulty and will need to be replaced. You can find replacement thermostats in our shop.
Also, if you have a digital Carel thermostat we recommend that you do a factory reset on the thermostat. To do this follow the instructions in the 2-Install-Carel-IR33-Operating-Instructions-1G60875-1G60890. If you suspect that the temperature sensing probe is not working correctly you can test this by checking the resistance of the wires against the temperature using the table in 3-Support-NTC-Chart