My Alder-Barbour fan on the compressor unit in my 1988 Catalina is loud, I think the bearings in the fan are wearing out. I think I can replace the fan and either connect the new wires or splice them, the fan appears to be 12v and about 4 5/8" square.Is there a certain amount of CFM the fan must move?Any suggestions or help for replacing is greatly appreciated.Thanks,Steve M.