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Pressure Switch Location

jomar
jomar Member Posts: 1
in Gas Heating
Hello. I just purchased a home with an older furnace: Lennox Whisper Heat, G20Q3/4E-100-3. An issue has come up. The furnace continues to blow air but it isn’t hot. The pilot flame comes on but not the burners. I changed out the limit switch and air filter but same problem. Now I’m trying to find the pressure switch but I can’t find it. In every video of all other furnaces it seems obvious because there are clearly hoses going to a device but not on this furnace. Mainly looking for help to find the pressure switch or any advice on how to fix this. It’s cold out, thanks.

Comments

  • worldclasshvac
    worldclasshvac Member Posts: 15
    Can't just change parts you will end up with the cost of a replacement furnace.  Start with cleaning the flame sense rod.  If you have pilot and no main burner it may not be sensing flame.  If you have 2 wires to gas valve test and see if you have 24vac once pilot lights at those pins on the valve.  Those older Lennox have board issues eventually with age.  Universals are cheap thankfully
  • Jamie Hall
    Jamie Hall Member Posts: 24,752
    Do you have the manual?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England

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