Troubleshooting Your Absorption Refrigeration Unit

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  • 1-3 hours
  • Beginner
  • 1-50

Absorption refrigeration is an infrequently used alternative to compression refrigeration. Absorption refrigerators use a solution of ammonia and water as refrigerant fluid. A gas flame heats the ammonia and provides the energy that drives the cooling process. Ammonia absorption refrigerators are often found in campers and recreational vehicles. These models are generally very simple and have few moving parts. If you notice that the unit is not cooling properly you will have to troubleshoot it. This is a very straightforward process. There are three main principles behind the proper operation of an absorption refrigerator. Place the refrigerator on a level surface. Make sure that it is adequately ventilated. Check that the correct heat is being applied in the boiler. As long as there are no leaks, this should be enough for the refrigerator to work properly.

Check for Leaks

There are several red flags that will help you quickly identify serious problems with the absorption refrigerator. A strong ammonia smell near the unit indicates a refrigerant leak. Also, check for deposits of yellow-green powder on the exterior of the refrigerator. This is sodium chromate and its presence also indicates a leak. Finally, listen for a conspicuously loud percolating or gurgling sound when the unit operates.

Check for Level Mounting

Placing the refrigerator on a level surface is necessary for proper drainage of the condenser and rectifier. Use a spirit level to verify that the refrigerator is not tilted. More sophisticated electric models may have pumps and other apparatus to minimize the importance of this.

Check Ventilation

Analyze the physical location of the refrigerator. The installation should limit open space to the back and sides of the refrigerator. The installation should also avoid air pockets. The amount of ventilation required depends on weather conditions; more ventilation is required during hotter weather.

Check Heat

Deviations from the correct amount of heat will alter the ratios of ammonia and water in the refrigerant mix. This reduces the efficiency of the refrigerator. If the refrigerator heats the solution with an electric resistor, it is probably heated to the right temperature. However, gas flames may need adjustments. Check the gas pressure and the seals on the gas lines. Inspect the switch, thermostat, and igniter, as well as the flue and burner. Another way to check is to take the temperature of the boiler and absorber after approximately 1 hour of operation. The two temperatures should be the same at this point.

Repair or Replace Cooling Unit

If the above three criteria of level mounting, adequate ventilation, and proper heat are met, the absorption refrigerator should work. If it does not, the cooling unit is probably broken. This could happen for several reasons. If the unit is operated off-level, a siphon pump that was covered with refrigerant may have been exposed to air. It would then corrode, and the corrosion can block the refrigerant line. If the back of the cooler heats up but the box doesn’t chill, this is a strong indicator of a blockage. The cooling unit may be sealed at a specific pressure and only a certified technician will have the tools and training to repair it.