The refrigerator compressor compresses the refrigerant, turning it into liquid and causing it to heat up. The refrigerant loses heat through the condenser coils on the back of the unit, and then pumps the refrigerant through an expansion chamber — where it quickly vaporizes and chills, making the refrigerator cold.
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But the compressor doesn't run all the time, only during the cooling cycle. It also needs help starting up each time the cooling cycle begins. This is the job of the refrigerator compressor relay. If you see signs that this start relay is bad, such as your refrigerator not cooling, you'll need to replace it.
Refrigerator Not Cooling
The most obvious sign that your start relay isn't working is the lack of cooling caused when the compressor never starts up. You can usually hear the intermittent humming of the compressor throughout the day. If this sound never happens and the temperature inside the fresh food compartment and the freezer begins to rise, then there is a good chance the start relay isn't functioning properly.
Clicking Relay Noise
Each time the start relay kicks the compressor on, there is an audible click. This click happens whether the compressor actually comes on or not. If the compressor does not come on when the start relay tries to start, then the start relay will try again in a short time, which typically occurs in intervals of two to five minutes. This repeated clicking is a likely signal that the start relay has failed and needs to be replaced.
The Shake and Rattle Test
A physical test of the start relay can be the most effective way to determine whether it's working or not. The start relay is located inside the same compartment with the compressor and is plugged into the back of the main device. Disconnect the power to the refrigerator and open up the compartment. Unplug the start relay from the compressor and give it a shake.
If you can hear rattling on the inside of the start relay, then the part is bad and will have to be replaced. If it's not rattling and appears to be in good condition, you may have a problem with the actual compressor. Compressor repairs are far more serious and expensive.
Replacing the Start Relay
If you're not an experienced DIY-er, you may prefer to call a refrigerator repair specialist for this job. But if you do attempt this project, be sure to unplug your refrigerator by pulling the power cord completely out of the outlet before you begin. And you may need help to pull the refrigerator away from the wall. Check your user's manual for the refrigerator start relay wiring diagram and the location of the start relay.
Replacing the start relay on your refrigerator is as simple as unplugging the bad component and replacing it with a new one. Simply remove the compartment cover with the power disconnected from the appliance. Pull the bad relay out of its socket, and plug in a new one of the same type. This should take care of the problem, and your refrigerator will begin working normally again.