I have an older Trane XL1200 gas pack furnace/AC. I just tried to turn on the furnace and nothing happened. Looking at the control board the led code told me it was a pressure switch problem. The inducer fan was not turning (rusted stuck). I replaced the inducer fan and now the furnace will go through the start-up sequence (check high limit switch, check flame rollout switch, turn on inducer fan, check pressure switch, turn on spark igniter, send voltage to gas valve) but it fails to light and goes into system lockout (no flame). I checked the voltage to the gas valve and it was 60V AC while the igniter was firing! The gas valve would click but the furnace would not fire. It should be 24V AC. To check the gas valve I disconnected the wiring from the valve and I connected 24V AC to it and it would click but I could not hear gas flowing or smell any gas. Do you think the gas valve is bad or the control board since it is supplying 60V AC to the valve?

  • What are you using to measure voltage? – ThreePhaseEel Nov 4 '19 at 4:54
  • A volt meter. It's a two stage gas valve with three wires going to it. I get 60V AC on both red and brown wires to the common black wire. – Chris Nov 4 '19 at 17:30
  • What make and model is said multimeter? – ThreePhaseEel Nov 4 '19 at 23:18
  • It is a GE Digital Multimeter model GE2524. – Chris Nov 5 '19 at 15:07
  • Hm. Can you try measuring the resistance of the gas valve windings please, as well as posting an exact model number for a) the furnace and b) the gas valve? – ThreePhaseEel Nov 6 '19 at 1:22

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