2006 Coleman air handler with king heat pump. Would not come on and no power to thermostat (blank). Found 3 amp fuse blown and replaced. Fan worked, switched working thermostat to cool and fuse blew. Another fuse holding contractor in and all works. One dark spot on contractor coil, but does not seem to penetrate coil windings. Pal says circuit board and I say contractor. Advice please.. THANK you..