# Lennox Furnace No Gas to igniter



## bprosa (1 mo ago)

10 to 12 yr Lennox ML180UH nat gas furnace. Gas valve does NOT seem to open after igniter lit for about 5-7 seconds. It glows red. Control board red and green lights flash simultaneously slow at first, then fast which indicates normal and call for heat. When the two gas valve wires are DISCONNECTED from gas valve and tested for voltage, the reading is just above 24v, but only for about 2 seconds and this happens after about 5 seconds after igniter starts to light. It should be for at least 4 seconds per the manual and back cover. Also, other videos say about 4 seconds. Now, when I test the voltage with the two wires CONNECTED (probes are attached to back of connectors on the gas valve) after the igniter lights for about 5 seconds, the meter reads only about 4v (four) and only for a split second before the entire system restarts. Also, the "watchguard" or lockout safety, does not seem to be working. The furnace will continue the cycle for at least 10 tries, then I manually turn it off or lower the thermostat via WiFi. 
Note: Replaced upstairs thermostat with NEST worked fine. Then the Flame Sensor went bad. Replaced it, and then a month later, no gas coming out.
Thank you for any help.


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