Board miss wire

[ddog1]

I serviced a 3yr old tempstar split system attic furnace today and am kinda stumped. Found fan not working so I checked out the board and find the HI SPEED blower lead connected to the EAC pin on the board and the HI SPEED pin not connected to anything. Homeowner tells me another company changed out the original 3 yr old board a month ago and says the a/c worked O.K. My question is what effects to the indoor blower motor would there be if eac is what is powering the motor when thermostat asks for cool.

[mark beiser]

The motor would get power like normal in the cooling mode, but the relay and conductors on the board that powers the EAC terminal may not be able to handle the current used by a motor. Could possibly have damaged the new board.

The real danger comes when the unit is run in the heating mode. The board would be sending power to two speed taps on the motor at the same time if there is a motor leed connected to the blower output for heat on the board.

Obviously that could damaged the board and the motor.