Replacing start capacitor for compressor - help please

There should be two windings and they are mechanically spaced. To make the motor work the windings get their voltages out of phase and the capacitor does that. It is driven by AC voltage so the voltage is increasing in a sine wave shape followed by a reversal of voltage.

Put simply, one winding has voltage to it to "move" the armature part way round and then the next winding gets the phase shifted voltage (power) to move the armature on again. Then the voltage reverses and the rest of the rotation carries on.

For lots of power and no capacitors, three phase power does it, each of three windings getting their voltage in sequential steps.

Hi Chaps, sorry been busy with work and have only just got around to having another look at my compressor - glad it sorted yours out though Mike! Unfortunately mine is still no go, changed the cap but it still just hums and sits there looking at me! I will have a look at the video you posted Mike and see if I can trouble shoot the other components, though I am not very electronically minded. I have had a look inside to see if I can turn the motor manually but it is completely sealed once you get past the outer case and has no way that I can see to get to any revolving parts to find out if it is seized. Thank you for all of your comments and suggestions I will work though them.

If it does not work I may be giving Father Christmas a nudge to see if he can come up with the goods!

Cheers, Simon

Looking at that video I have tested the start relay using a meter and not getting any reading regardless of which way up the relay is when tested across the connections. I have tried with continuity setting and with ohm's (200) and there is no response. Does this sound like it is the culprit? If so which are the important numbers on the casing to specify a new part?

Many thanks, Cheers, Simon