Maytag Refrigerator not Cooling

[TechnicianBrian]

Model #MSD2456GEW, this side by side refrigerator stopped cooling after several years of service. The customer returned from a weekend away to find water everywhere from the melted ice cubes, and some rather unpleasant smells emanating from the liner. But fortunately for them, it wasn't time to go shopping for a new refrigerator. This unit just needed a quick part replacement to make everything cool again.



Your typical household refrigerator uses a compressor driven sealed system to provide cooling within the unit. The purpose of the compressor is to pump refrigerant through the sealed system where heat within the unit can be absorbed and then released to the outside. If the compressor fails to operate, the refrigerant can't do it's job, and the result will be melted ice cream everywhere.

In order to get the compressor pumping, the motor inside the housing will have two internal windings to get the thing started and to keep it running. Referred to as the start and run windings, they both work together to give the motor the extra push it needs to get the compressor running up to speed. Once started, the motor will no longer need the full help of the start winding, and will continue to operate using mostly the run winding for primary motor operation. To make all this work, compressors use what is commonly referred to as a start device to get the compressor motor running, and to cut back on the start winding when it is no longer needed. These will usually attach directly to the compressor electrical pins and may also contain an overload protection device used to shut down the compressor due to overheating.


The most common version of the compressor starter is the PTC (Positive Temperature Coefficient) which means as the temperature increases, the resistance increases. Inside is a thermistor disk that allows current to flow to the start winding. As the current draw of the start winding increases, the temperature of the disk will increase causing the thermistor to increase in resistance. The resistance of the disk eventually gets high enough to limit current flow through the start winding without opening the circuit. This allows the motor to run primarily on the run winding, with a little help from the start winding.

The new PTC Starter

Now back to the problem at hand. While listening to this refrigerator for a few minuets, I heard the tell tale sound of the compressor trying to start (you will hear it hum) and then a click or snap which is sound the overload makes when it trips opening the circuit. Because the compressor cannot start using the run winding alone, the overload bi-metal will quickly get hot and open the circuit. Once it cools down, the sound pattern will continue as long as the unit is plugged in. Figuring I was dealing with a failed start device, I made my way back to the compressor, removed the starter and gave it a shake. These starters have no moving parts, so if it sounds like a baby rattle, it's definitely seen better days. This one not only sounded bad, but once I took it apart, it didn't look to good either. I did a quick resistance check of the compressor to make sure it was still in good shape, then installed the parts from a new start kit. Once the wiring was re-connected, the compressor came back to life, and the sealed system began cooling shortly there after.

If you find your refrigerator not cooling, make your way to the compressor a see if it is working. A working compressor that is not cooling will often indicate a sealed system problem, but if the compressor isn't operational, time to take a look at the circuit and find out why.