I have a lennox furnace. The spark igniter lights the pilot. but the burners don't come on.?

Question

A few seconds later the blower comes on. Pilot light is still lit. There is 24 volts across the orange and blue wires. 9 volts across the blue and red wires. 12 volts across the orange and red wires. Do I need a new gas valve or maybe the intermittent pilot igniter control? or something else.

Answer 1

I would guess the control unit is gone. Call Lennox and tell them what's wrong and what it's doing.

Answer 2

There is a safety device called a "Thermocouple" that senses flame from the pilot. It doesn't allow the gas valve to open to the burners if it doesn't sense heat. Perhaps the bulb of the thermocouple is out of position and not in the path of the pilot flame. Thermocouples also fail( that is part of the safety feature). It is easy to replace and an inexpensive part.