What is PTC Relay and its function in Refrigerators

PTC stands for Positive Temperature Coefficient. This refers to the Alloy chip inside the relay whose resistance increases as its temperature rises. When the compressor first starts up, the resistance of the PTC's chip is very low and it lets current flow into the start winding of the compressor. As the current flows thru the PTC, it heats it up and also raises its resistance to the point that the start winding is effectively taken out of the circuit, which is what you want to happen as soon as the compressor gets going.

How a Refrigerator PTC Relay Working and Function

In the refrigerator compressor we use the split phase single phase induction motor  and this motor have internal two types of winding which we called running and starting winding or auxiliary winding. We know that a single phase motor did not start with a starting capacitor or a staring current.
In simple words the refrigerator ptc relay gave a current to start winding and when the motor stat up the ptc compressor relay remove the start winding from the circuit.
So the above is a simple and short explanation of refrigerator relay and it's working.