Hello all,

just bought our first house this Feb. The heat stopped working the day we closed, go figure. Turns out it was the circuit board, or more accurately, the ignitor wire that was hardwired into the board came loose. Repairman replaced the board and wire which was a $500 ordeal. Lennox furnace is about 8 years old.

Today I tried testing out our central AC, the unit is only a year old. It is a outdoor unit connected to the Lennox. The AC unit seems to work fine, it kicks on with the thermostat and line gets cold. The problem is that the furnace blower does not kick on either in manual or auto modes. Turn the furnace to heat and it works fine. Outdoor/indoor temps about 70F.
Any advice appreciated.

 

Look at the circuit board. Usually there is a strip of terminals labeled fan or blower. On that strip of terminals often terminals for "heating speed" (HS) & "cooling speed" (CS). make sure wires to the fan are hooked to both.

 

Most of the time the black wire off the blower motor should go to CS on the board. Tape off any wires not on the board from the fan motor. Dont run outside unit till you get the blower working on cool.

ED