Troubleshooting refrigerator compressors

Updated February 21, 2017

Fridges are our chilly friends, so chilly and complex in fact that we rarely give them any mind while they chug away, keeping our food unspoilt. Fixing a refrigerator can be tricky business, and is usually best left handled by a professional. However, if you are one of those handy types who love to get your fingers dirty doing a bit of DIY around the house, troubleshooting a refrigerator compressor can be an enjoyable challenge.

Not running

If your fridge has power but it does not cool down, or doesn't run at all, you should test the compressor motor to see if it is working. To troubleshoot the compressor motor, first unplug the unit to prevent electric shock. If the compressor on your refrigerator has a capacitor, an electric component that generates electricity, this must be discharged to prevent electric shock. Even when a fridge is turned off, the capacitor can hold a charge.

To get to the compressor, you will need to get to the back of the fridge. The compressor is at the bottom of the unit. You will need to remove the terminal box cover to reveal the compressor motor. You will need to remove the compressor relay by pulling it out. You can then check the motor with a multimeter, using the resistance-tester at each terminal. The reading should be zero ohms at each terminal. After this, set the multimeter to X1 and touch the reading instruments to the metal housing for the compressor. The reading should be the infinity sign. If it gives any reading other than this, you should contact a professional.

Intermittent running

If the compressor is cutting out, or intermittently running, unplug the fridge and check the compressor relay. A relay with a fault will cause the compressor to cut out randomly, or never come on at all. Access the compressor from the lower back of the fridge. The relay will be located on the lower-right-hand side, inside the terminal box. Remove the terminal box cover. You can remove the compressor relay, which looks like a small copper coil, then pull it straight out. Remove any wires coming from the terminal box at this time, and check whether or not there is any corrosion on the relay, or the terminal box. If there is, these parts will need to be replaced.

Loud noise

If your fridge is incredibly noisy, you should check the status of the compressor mounts. Before inspecting the compressor mounts on your refrigerator, make sure to unplug the unit to avoid shocking yourself. The compressor motor of your fridge sits on small plastic mountings that absorb the vibrations emanating from the running compressor. Over time, these plastic mounts may become brittle and fall apart, leaving the compressor free to vibrate against the fridge metal, making a loud noise.

To replace these mounts, you must remove the compressor cover, and unscrew the retaining clip that holds down the unit. Check the status of the mounts to see if they are hard or brittle. If they are, they should be replaced. Put in your new mounts and tighten down the clamp.

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