Troubleshooting a Defective Cooling Unit






Testing the Cooling Unit

First of all, if the cooling unit cools properly on one heat source (i.e. gas or electric) and not the other, then the cooling unit, with only a few exceptions, is good and the problem lies in the heat source that is not functioning properly.

Secondly, there are obvious signs of a bad cooling unit.

  • If you smell ammonia in or around the refrigerator, and you haven't recently used ammonia for cleaning, the cooling unit is bad. No further testing is necessary.

  • If sodium chromate is present on the outside of the cooling unit, the cooling unit is bad. Sodium chromate is a yellowish-greenish powder in solution inside the cooling unit. If sodium chromate is outside the cooling unit, the cooling unit has a hole in it.

  • If you hear a relatively loud gurgling or percolating sound when the refrigerator is in operation (being heated), it is a sign of a bad cooling unit. The key words here are "relatively loud". A good cooling unit percolates when in operation, and if you get close enough and listen carefully enough, you can hear it percolate. However, if you hear noise a few feet away, it is a sign that the cooling unit has lost pressure and is bad.

Testing the cooling unit is simply insuring that the three necessary requirements for the operation of a cooling unit (level, ventilation, correct heat) are met. Do whatever it takes to meet these requirements. If you suspect a venting problem, pull the refrigerator and set it on the floor. In fact, pulling the refrigerator and setting it on a level floor meets two of the requirements and leaves only one, correct heat, to worry about. Always test the refrigerator on the electric heat source, unless you are unable to because you have a gas only refrigerator. The reason for testing on the electric side is if the electric heat element gets hot, you can be better than 95% sure that you have correct heat, whereas even a poor gas flame will produce heat. To insure that the heat element is getting hot, you can touch the insulation pack (a rectangular or round sheet metal container filled with insulation located directly above the propane burner) to see if it is warm after about a half hour of operation. CAUTION: touch the pack lightly at first; it is possible under certain conditions for the pack to get super hot and burn you. If the insulation pack does not get warm, you have an electrical problem that needs to be corrected before continuing. If an electrical problem is not the electric heat element itself and/or you want to insure that some other electrical component (such as a thermostat) is not interrupting the heat element, you can hot wire the heat element for better testing conditions. The only weak link in this testing procedure is the less than 5% of the time that a working heat element is not producing the correct heat. See hot wiring (below)for information on verifying the output of the heat element.

After you have provided the cooling unit with its three requirements, allow plenty of time for the cooling unit to function. You should see signs of cooling in the freezer after about two hours. Allow six to eight hours, or even over night, for an empty refrigerator to come down to temperature. The ammonia absorption style of refrigeration is slower than the compressor style in terms of initially bringing the refrigerator down to temperature. However, once the desired temperature is reached, there should be no problem in maintaining that temperature.

If you have done everything in this section up to this point and the cooling unit does not work or does not work well, the cooling unit is bad and will need to be rebuilt or replaced.


Hot Wiring

Hot wiring refers to simply connecting the 120 volt heat element straight to 120 volt power. Hot wiring by-passes all other controls and eliminates them as possible problems when testing the cooling unit.


To hot wire, disconnect the electrical connections between the refrigerator and the 120 volt heat element (leaving the heat element in place inside the insulation pack of the cooling unit) and then by whatever safe means necessary connect the heat element straight to 120 volt power. If the heat element gets hot (you can tell by lightly touching the insulation pack after about a half hour of operation) you can be better than 95% sure that you have met the correct heat requirement.  Now, you have bypassed the controls so let the unit run 8 to 10 hours or overnight and check the temperature.

Hot wiring is pretty straight forward if you have only one heat element (120 volt) with only two wires. You connect the two wires to the 120 volt power, and it doesn't matter which wire goes where (no polarity). However, not all refrigerators are that simple. Below are other possible configurations, along with a few clues that might help locate the 120 volt wires necessary for hot wiring. In some cases it may be necessary to locate a wiring diagram.