Base I/O Fuse Open - 3100 Series

The base I/O relay board provides internal power to the logic of all circuit boards in the system. Input power is applied to the L1 and L2 240 terminals on the base I/O relay board. This board has two fuses and they operate as follows:

• The 1/4 amp fuse (order item # 1024036) provides power to all of the circuit boards in the system. If this fuse is open, the system's display does not illuminate. This input has over voltage circuit protection; therefore, a high voltage surge or incorrect input voltage wiring can cause the fuse to open.

• The 5 amp fuse (order item #1024037) protects the variable voltage (triac) output. This output passes voltage from the L1 terminal to the blower output terminal. If this fuse is open, the most probable causes would include a shorted blower, wiring, or limit switch.