Hello, my name is Wil43

What is the problem when the condensing fan is running and the compressor is not running when the contactor is engaged ? :confused:Please help me .

With the power off check all the connections on the compressor then check all the power connections to the compressor capacitor and back to the contactor that activates the fan and compressor in the outside unit.

If the capacitor looks swollen or is leaking oil it is probably defective and needs to be replaced. Always replace with the EXACT valve and voltage rate listed on the old capacitor.Again make sure the power is off. If you want to test the capacitors in your unit a simple OHM meter will test for continunity only. You need a real capacitor test meter to actually check for value. A industry standard of 6% is allowed for capacitor variation.

Post back with the results of your adventure.

do you hear a humming noise from the compressor for a short time and then the noise stops(like its trying to start but wont?). THis would suggest a bad capacitor, a bad compressor, or incorrect voltage(possibly caused by contactor, or many other things). Your best bet is to have a pro tech into diagnose the problem. Good luck.

First thing you should probably do is turn the power off, remove the panel and inspect the electrical circuit for burnt wires, swollen run capacitor and burnt points on the contactor.
You may want to try a start assist kit which consist of a start capacitor and a potential relay. If compressor still fails to start you may want to plan on replacing your compressor.