How to Check a Refrigerator Compressor [Quick Guide]

If you are wondering how to check a refrigerator compressor, you have come to the right place. Let us guide you to check your compressor correctly.

How to Check a Refrigerator Compressor

How to Check a Refrigerator Compressor

It is essential to disconnect a refrigerator from electric power before performing any repairs. To begin, pull the refrigerator from the surrounding wall and disconnect it. If it is impossible to reach the power cord, turn off the circuit breaker.

Next, create enough space at the bottom back of the refrigerator for you to fit and work. Get a digital multimeter and set it to Ohms. Locate the start relay on its mount in the compressor. The relay is typically small, but you cannot miss it.

Once you unmount the start relay, you will see the start, run, and common pins. Some compressors will mark them with alphabets S, R, and C while others won’t. So, if your refrigerator compressor has no markings, set the meter to R x 1 scale. Then, locate the two electrical pins out of the three with the highest resistance reading.

Now, use the meter’s probes to test between two pins. The two pins with the highest resistance are the start and run pins. The third one automatically becomes the common terminal. Now, if you find an O.L reading between any two of the electrical points, the compressor has an open circuit and you should replace the compressor.

Other Things to Check

Another way to check a refrigerator compressor is to check the motor windings. Get a reading between the common and start and the common and run electrical pins using a multimeter. The readings should stay within 0.5 ohms, one to the other.

However, the motor winding that shows the lower reading is shorted if the readings are not within the recommended ranges but veer off significantly. It indicates the compressor is faulty and needs a replacement.

You can also check the reading between the housing of the compressor and each electrical pin. That is, if the motor winding test is inconclusive. The multimeter should read O.L while you take the readings. So, if you get any other readings, replace the compressor because the motor windings are shorted.

Thermostatic Control

If the windings of the compressor’s motor test well, check the thermostatic control. The control is a switch so set it between four and five. Test the continuity between the relay wires and the plug. You should get a reading of 0.000 when you test one start relay wire and one side of the plug. If the meter shows O.L, the control is malfunctioning and needs a replacement.

But if the control shows the correct reading, the compressor fault may stem from the start relay itself. It could also be that the compressor is locked up or has worn valves or bearings. Replacing the start relay is quick, easy, and inexpensive. Replacing the compressor, on the other hand, is the job of a licensed refrigerator technician, according to the law in the U.S.

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Refrigerator Compressor Relay [How to/Issues & Solutions]

Refrigerator Gas [Questions, Problems & Solutions]

How to Check a Refrigerator Compressor Relay

To check the start relay of a refrigerator compressor, do the following:

Unplug the refrigerator from the wall outlet. As with the compressor, don’t test or repair any part of the appliance while it is still connected to electricity. Next, find the relay on the side of the compressor and unmount it.

Give it a shake to determine whether or not it rattles. If the relay rattles, it is a sure sign that it is faulty and needs a replacement. The same is true if it smells burnt. But if the relay does not rattle, check it for continuity.

There are usually three terminals on a relay. Each one is marked with letters, so you may find S, L, and M on the terminals. Take a multimeter and place its probes on any two of the terminals. Turn the relay bottoms up while the probes are still attached to the terminals. You should hear an audible click and the meter should read infinity.

Do the same all across the terminals. Test terminals S and M, S and L, and M and L. If the reading on the meter changes, replace the start relay.

How to Check Refrigerator Compressor Gas

To check the gas or refrigerant in the refrigerator, do the following:

Step 1

Place a hand close to the condenser coils. You should feel some warmth coming from them. But if the coils have no warmth or feel cold, it may mean there is little or no gas running through the refrigerator.

Step 2

Disconnect the refrigerator from power and put one ear to the refrigerator’s side. You should hear the gas gurgling and hissing. If you don’t hear these noises, the gas may be low. But it could also be a fault with the condenser coils, condenser fan, defrost system, compressor, or cap tube.

Step 3

Remove the interior rear panel of the freezer to see the evaporator coils. Now, reconnect the refrigerator to electric power and allow it to operate for several minutes with the panel still uncovered but with the refrigerator door shut. If the coils have no frost on them after the refrigerator has run for several minutes, the gas is low or absent.


Hire a refrigerator technician to check the compressor if you suspect it is no longer working as it should. But if you are a DIYer and want to know how to check a refrigerator compressor yourself, this article will guide you.

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