Furnace Control Board keeps blowing fuses.?

The coil of the contactor for the outdoor condensing unit is energized by the control voltage. Control voltage is induced by the transformer. Both primary and secondary power are connected to the control board at the appropriate terminals. The 24 volts of control voltage go away from the board from the terminal "R". A red wire from a bundle is used and the other end goes to the thermostat. From the thermostat, the 24 volts continues from the terminal "Y" along the yellow wire back to control board's terminal "Y". A second yellow then carries the 24 volts outside to the coil of the contactor. Another wire must then return from the common side of the contactor's coil to the common terminal "C" on the control board. The coil of the contactor should show a measurable resistance, typically around 17 to 24 ohms of resistance and would then be considered good. If it showed a really low resistance like .8 or under, it would be indicating a shorted coil on the contactors. The shorted winding of the contactor coil will allow an uncontrolled flow of current. If that flow is provided by the transformer, the windings of the transformer will overheat and burn out. It's called "letting the smoke out". The fuse protects the transformer from letting it's smoke out. Sounds like the coil is shorted on the contactor. Easy replacement of the contactor. Takes about 30 minutes.