The compressor on our 3 1/2 yr old fridge/bottom freezer was making a clicking and buzzing noise and stopped working. I unplugged the unit, removed the relay/overload and capacitor assembly and then reinstalled them. The compressor started working again and was working great for 2 weeks.

Then the noise came back and the compressor stopped again. I replaced the relay/overload (I used the original capacitor) and the compressor started working again. This time it worked for about 6 hours.

I removed the new relay/overload and reinstalled the original. Again, it ran for about 5 or 6 hours (made a few turns of ice) and stopped again.

I'm guessing the compressor is bad, but before I call for warranty service I would like to know if a bad capacitor or any other non-warranty part might cause this type of behavior.

Any advice would be greatly appreciated,
Sufax

You could also check the motor's windings.

Here is the tech sheet with the resistances
Be sure to check them to the compressors case, should be infinite ohms.
http://www.servicematters.com/docs/wiring/Tech%20Sheet%20-%208171102.pdf

And a couple links on how to do it, first link is the better of the two
Refrigerator Repair Guide: How To Fix a Refrigerator - ACME HOW TO.com

http://www.applianceaid.com/refrigerator.html

[COLOR="Blue"]Do these readings confirm that the compressor is OK[/COLOR]
Well it tells you that the windings are OK but does not tell you if the compressor is OK mechanically.

[COLOR="Blue"]and I need to replace the capacitor?[/COLOR]
It is worth a try.
[COLOR="Blue"]
As a side question:
I can get the compressor running again by turning the freezer cold control to off for an hour or 2 and then turning it back to normal. Is it coincidence that each time it works fine until approximately the next defrost cycle and then won't start back up again?[/COLOR]
Not sure why this would be.
Perhaps it is just the compressor overheating and then not starting.
You did not say but have you checked to be sure the condenser (compressor fan is running.
Also a leaky capacitor can cause it to overheat.

I installed the new capacitor, and the compressor worked for a couple of hours. Then the clicking came back.

With the old relay/overload and old capacitor it runs for about 6-7 hours then the clicking starts. With the new relay/overload and the new capacitor it runs for about 2 hours then the clicking starts. When the compressor runs, it is quiet and efficient.

Although it is only 3 1/2 yrs old, and the windings seem to test good, I guess that I have to assume at this point that the compressor is the problem.

Thanks for all of your help,
Sufax

Contrary to what Denman is saying, simple compressor winding resistance checks will not prove much except that they are not blown open. You may have shorted turns on the run winding and only a very accurate check with a comparison to the factory data, (which is usually not available), would determine a problem.Even then, the use of a low dc voltage ohmeter would not confirm a problem if the winding breaks down when 115 volts is applied.
Compressor motors produce less running torq when they get hot. Either your compressor is getting hotter than normal, it has shorted turns in the run winding, or there is varnish buildup in the compressor. Rather unusual it takes so long to shut down.
I would elliminate intermittant problems by tapping on the control housing in the freezer, you might have an intermittant cold control.