Hi, I want to connect a (two-wires)fan-motor to a relay.The compressor has a relay with an overload protector integrated in it.

The relay has three terminals that go to the compressor and another two marked with L and N. Can I connect one terminal to L and the other to N to power the fan?

 

It depends on the Fan.
The Motor-Starter will see the Fan-Load as additional Compressor-Load and
may cause the Motor-Starter to trip prematurely.

It's generally not a good plan.

Use the "L & N" Terminals to drive the Coil of a second Relay used exclusively for the Fan-Motor.

Compressors are usually higher Voltage, so check the Voltage across the L & N Terminals
to make sure that You get a Relay with the proper Voltage rated Coil.
.
.
.

 

It depends on the Fan.
The Motor-Stater will see the Fan-Load as additional Compressor-Load and
may cause the Motor-Starter to trip prematurely.

It's generally not a good plan.

Use the "L & N" Terminals to drive the Coil of a second Relay used exclusively for the Fan-Motor.

Compressors are usually higher Voltage, so check the Voltage across the L & N Terminals
to make sure that You get a Relay with the proper Voltage rated Coil.
.
.
.

Thanks for you answer. Originally, the older compressor had an amperimetric relay. The new one works perfectly with the compressor alone (the power chord is connected to L and N) but I need to connect the condenser fan and the thermostat. The only thing I want to avoid is a short-circuit.

 

OK, I can see that there are guesses. So here are my guesses, since the information was not given, but is needed to provide a correct answer. First guess is that the condenser fan will run when the refrigeration compressor runs, and not run when the compressor is not running. The second guess is that the fan is designed to run from the same power as the compressor. Both of these guesses are made based on the guess that it is a normal refrigeration setup.
So the condenser fan should connect to the same L (line) and N (Neutral) wires as the line cord. Then it will run when the compressor runs. Now, to add thermostat control, The "L" connection side of the line cord will need to connect to one terminal of the thermostat, and then the other terminal of the thermostat will need to connect to the "L" terminal of the compressor/fan, where the line "L" wire was connected. That is commonly called a series connection of a thermostat. The fan connection across the compressor is commonly called a "Parallel" connection.

 

OK, I can see that there are guesses. So here are my guesses, since the information was not given, but is needed to provide a correct answer. First guess is that the condenser fan will run when the refrigeration compressor runs, and not run when the compressor is not running. The second guess is that the fan is designed to run from the same power as the compressor. Both of these guesses are made based on the guess that it is a normal refrigeration setup.
So the condenser fan should connect to the same L (line) and N (Neutral) wires as the line cord. Then it will run when the compressor runs. Now, to add thermostat control, The "L" connection side of the line cord will need to connect to one terminal of the thermostat, and then the other terminal of the thermostat will need to connect to the "L" terminal of the compressor/fan, where the line "L" wire was connected. That is commonly called a series connection of a thermostat. The fan connection across the compressor is commonly called a "Parallel" connection.

Thanks for your help. I have attached a sketch of the circuit.

 

The circuit as shown in the drawing is correct. You do need to verify that the current switching rating of the thermostat switch is adequate for the compressor current requirement. If the thermostat controlled the previous compressor then probably it is adequate.