Why does a compressor need a start relay?

A compressor motor requires a significant surge of power to overcome its initial inertia and begin rotating. The start relay provides this temporary boost, engaging a start winding that gives the motor the necessary torque. Once the motor reaches operating speed, the relay disengages the start winding, allowing the compressor to run on its main winding.

How can I test a compressor start relay?

A common method to test a start relay is using a multimeter to check for continuity or resistance across its terminals. For PTC (Positive Temperature Coefficient) relays, resistance should be low when cool and increase as it heats up. If the relay shows infinite resistance when cool or an open circuit, it may be faulty. Always consult your appliance's service manual for specific testing procedures.

What is the difference between a start relay and an overload protector?

While often found together, the start relay and overload protector serve different functions. The start relay helps the compressor motor start by providing a temporary power boost. The overload protector, on the other hand, is a safety device that monitors the compressor's current draw and temperature. If the compressor overheats or draws too much current, the overload protector will trip, shutting down the compressor to prevent damage.

Refrigerator Compressor Start Relay Replacement

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1Pcs QP-02-4.7 3Pin 4.7 Ohm Refrigerator Start Relay Coolers Compressor Starter with 1Pcs 1/2HP Refrigerator Overload Protector

✅Package Content: 1 x Starter Relays 4.7 ohm 3Pin + 1 x Refrigerator Overload Protector 1/2HP.
✅Please note that this product is only compatible with QP-02-4.7 relay with 3 terminals. Not compatible with relays of other pin numbers. This kit is not suitable for all refrigerator compressors, only applicable to 1...
✅【Note】The maximum current that a 4.7 ohm relay can withstand is 12A. otherwise it will burn.
✅【Note】Please carefully compare the pictures we provide with your old parts. Please check if your old relay is 3 pins. To make sure it fits your refrigerator. please consider before buying.
✅【 Installation 】Installation needs to be completed by professional maintenance technicians. Please make sure to unplug the power plug and wear work gloves before installation. Wiring during installation: Connect the ...

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What the QP-02-4.7 does

The compressor start relay provides a temporary power boost to the compressor motor, helping it overcome initial resistance and begin running. Once the compressor is running, the relay disengages, allowing the compressor to operate efficiently.

Symptoms when this part fails

Refrigerator not cooling
Compressor makes a clicking sound but does not start
Refrigerator runs for short periods then shuts off
No humming sound from the compressor
Compressor feels hot to the touch

Compatibility

Fits the Samsung family. Specifically:

Any unit originally equipped with OEM part number(s): QP-02-4.
Check the model/rating plate inside your appliance and compare it against the fitment table on the product listing before ordering — this guide does not list specific compatible models because Amazon does not provide verified fitment data through this pipeline.

Also replaces: QP-02-4

Tools you'll need

Phillips head screwdriver
Flat head screwdriver
Needle nose pliers
Multimeter (optional)

Difficulty: Moderate · Time: 30-60 minutes

How to install the QP-02-4.7, step by step

Disconnect the refrigerator from its power source.
Carefully pull the refrigerator away from the wall to access the rear panel.
Remove the screws securing the compressor access panel and set it aside.
Locate the start relay attached to the side of the compressor and disconnect any wiring.
Gently pull the old start relay off the compressor terminals.
Align the new start relay with the compressor terminals and push it firmly into place.
Reconnect the wiring to the new start relay.
Reinstall the compressor access panel and push the refrigerator back into position, then restore power.

Related troubleshooting

If swapping this part doesn't fix the issue, check these next: