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-   -   Programmable thermostat not working in fan mode? (https://www.askmehelpdesk.com/showthread.php?t=630990)

  • Jan 27, 2012, 11:32 AM
    tmtater
    Programmable thermostat not working in fan mode?
    Thermoat heat and A/C blower work OK on "Auto", but can't run "fan on", I.e. Can't run fan continuously. Maybe I'm not wording the question properly, but I can't find this question anywhere on the 'net. Seems odd. Have a Lennox gas furnce. The green wire is connect at both the thermostat and furnace.
  • Jan 27, 2012, 04:07 PM
    mygirlsdad77
    You say the green wire is hooked at stat and furnace, but is it hooked to the G terminal on both?
  • Jan 27, 2012, 06:02 PM
    T-Top
    With some furnaces they will use 3 speeds on the blower-- high for cooling, medium for heating and low for continuous fan only. You will need to check for 24 volts at the furnace control board. With the thermostat set to fan on, you should have 24 volts on the G circuit. Check the voltage from C (common) to G. If you have voltage it's a board or blower wire that is bad.

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