GE Profile Making High Pitch Noise

My GE Profile refrigerator is cooling fine but making a very high pitch noise. The noise initially only was occassional, now happens more than half the time. Any suggestions as to what may be wrong? How do I fix it?

Yes, it would be the motherboard in the rear. Pull the refrigerator out, and there will be a panel in the back, that has 3 screws holding it on. Remove it, and that is where the motherboard is. The part# is WR55X10552. Tom