Ask Me Help Desk

Ask Me Help Desk (https://www.askmehelpdesk.com/forum.php)
-   Heating & Air Conditioning (https://www.askmehelpdesk.com/forumdisplay.php?f=150)
-   -   "pressure switch open with inducer on? (https://www.askmehelpdesk.com/showthread.php?t=290817)

  • Dec 10, 2008, 08:12 PM
    JJOHNSON27
    "pressure switch open with inducer on?
    I have an intertherm propane furnace, new in 2006 we just turned propane back on for the year, and it won't light. The red light is blinking 2 times & indicates "pressure switch open with inducer on" however I have no idea what that means or how to troubleshoot to fix. It hums like always before it kicks on, but there is no flame. Propane is on, ignition switch is on... any ideas? Please Thank u
  • Dec 10, 2008, 08:17 PM
    MarkwithaK

    Your pressure switch is more than likely stuck close. Your system will not fire with this condition. It is a safety condition to prevent the unit from operating with the inducer not running and the pressure switch jumped/closed. Turn the system off and pull on wire to the switch. Start the unit and wait until the inducer starts. Give it a few seconds and attach the wire you removed. If the system fires then you will probably be replacing the pressure switch.
  • Dec 10, 2008, 08:29 PM
    JJOHNSON27

    There are two wires, pull both?
  • Dec 10, 2008, 08:30 PM
    MarkwithaK

    Negative. Pull only one. Either one you want.
  • Dec 10, 2008, 08:35 PM
    JJOHNSON27

    Turned off power, unplugged 1, turned power back on. Inducer motor came on, before plugged in, 2 lights flashed, plugged back in, 2 lights still flashing. Any other thoughts? P.S. Thanks for your help, single mom, xmas time. P.S.S Inducer motor is hot
  • Dec 10, 2008, 08:37 PM
    JJOHNSON27

    Also have thermostat set to heat, auto fan, and 80 (which should kick the heat on)
  • Dec 10, 2008, 08:38 PM
    MarkwithaK

    Inducer could be failing but that wouldn't explain why your system is telling you that the switch is closed. Did you wait about 10 seconds before plugging the wire back in?
  • Dec 10, 2008, 08:42 PM
    JJOHNSON27

    Its telling me the pressure switch is open with inducer on?? Same thing as switch is closed?
  • Dec 10, 2008, 08:44 PM
    JJOHNSON27
    Clear plastic tube on bottom left side was very dirty. Removed & it had water in it!? Possible problem
  • Dec 10, 2008, 08:46 PM
    MarkwithaK

    Very much a problem. If the tube has water in it then you are getting moisture backing up in the system. Is this a high efficiency unit?
  • Dec 10, 2008, 08:48 PM
    hvacservicetech_07

    Can you hear water in the inducer? If so,I'd say the drain is plugged and not letting the water out of the inducer,thus it won't pull the pressure swith closed.
  • Dec 10, 2008, 08:48 PM
    JJOHNSON27

    Yeah
  • Dec 10, 2008, 08:51 PM
    JJOHNSON27

    I got the water out of the "j" tube & replaced. Anything further I should do?
  • Dec 10, 2008, 08:51 PM
    hvacservicetech_07

    Does the plastic tube connect to the inducer?
  • Dec 10, 2008, 08:53 PM
    hvacservicetech_07

    Remove the end of the tube that connects to the inducer,and blow through it. Does it feel plugged?
  • Dec 10, 2008, 08:54 PM
    JJOHNSON27

    The tube runs from the bottom of furnace, up to the black plate that the inducer motor is mounted on (from diagram looks like that plate is called the "front header box"?
  • Dec 10, 2008, 08:56 PM
    hvacservicetech_07

    Ok,remove the tube from the black plate and blow through that end.
  • Dec 10, 2008, 08:58 PM
    hvacservicetech_07
    Once you think you have the drain clean,power the furnace back up and see what happens. Does the motor seem to be running really slow? Can you hear the water slushing?
  • Dec 10, 2008, 09:00 PM
    JJOHNSON27

    Did that, wasn't clogged. Also blew through small gray hose that goes from gas regulator, up to pressure switch. It made a clicking noise up at the pressure switch when I blew into the bottom of it by the gas regulator.
  • Dec 10, 2008, 09:03 PM
    JJOHNSON27
    How would u like me to fire? Should I have gas ignitor to on, fan on, power on, and then turn thermostat on to see if it lights (normal startup) and does the front panel have to be on to have it work?
  • Dec 10, 2008, 09:04 PM
    hvacservicetech_07

    Gas valve on,fan switch auto and blower door must be on.
  • Dec 10, 2008, 09:05 PM
    hvacservicetech_07
    You can leave the top door off,just to see if it's going to light. Do you hear water slushing in the inducer?
  • Dec 10, 2008, 09:10 PM
    JJOHNSON27

    No water. But when I remove small grey tube from gas regulator, plug with my finger, the light turns solid red for about 6 seconds, then goes back to flashing twice.
    Is there a way to tell if propane is getting to the furnace, its on at the pig, but...
  • Dec 10, 2008, 09:11 PM
    hvacservicetech_07

    Does the ignitor ever glow?
  • Dec 10, 2008, 09:12 PM
    JJOHNSON27

    No glow
  • Dec 10, 2008, 09:13 PM
    hvacservicetech_07

    Ok,locate the pressure switch,do you see the rubber tube that is connected to the pressure switch?
  • Dec 10, 2008, 09:16 PM
    JJOHNSON27

    2 actually. Small & grey. One in front of the other. One goes to inducer motor & the other splits and goes to the box where u can see the flame and the gas valve
  • Dec 10, 2008, 09:18 PM
    hvacservicetech_07

    OK,the tube that goes to the inducer motor hooks to the pressure switch on the other end.
  • Dec 10, 2008, 09:19 PM
    JJOHNSON27

    Yes
  • Dec 10, 2008, 09:20 PM
    hvacservicetech_07
    Shut furnace off,remove tube from inducer only,power furnace and suck on the tube like a straw,you will hear a click keep sucking keeping a vacum on the tube until you see an ignitor glow.
  • Dec 10, 2008, 09:22 PM
    hvacservicetech_07
    Your furnace should have a plastic exaust pipe,does it vent through the roof or the side of the house?
  • Dec 10, 2008, 09:24 PM
    JJOHNSON27

    Did that, it glowed, then when I stopped, it stopped glowing
  • Dec 10, 2008, 09:25 PM
    JJOHNSON27

    Roof
  • Dec 10, 2008, 09:25 PM
    hvacservicetech_07


    Ok, two pipes?
  • Dec 10, 2008, 09:27 PM
    JJOHNSON27

    Two pipes go up through roof
  • Dec 10, 2008, 09:28 PM
    hvacservicetech_07

    How cold is it outside?
  • Dec 10, 2008, 09:29 PM
    JJOHNSON27

    19 degrees. And we just got DUMPED on with snow over the past 3 days
  • Dec 10, 2008, 09:31 PM
    hvacservicetech_07

    Most likely something is blocking the intake or exaust. It could be a chunk of ice or even a bird or wasp nest. When either pipe is restricted the pressure switch will not close.
  • Dec 10, 2008, 09:31 PM
    hvacservicetech_07
    K, check and make sure snow or ice is not covering the intake and exaust on the roof, I'm willing to bet you have a ball of ice over the intake.
  • Dec 10, 2008, 09:33 PM
    JJOHNSON27

    You're a genius. Thank u so much! I will get someone up there tomorrow to try and clean out. Thank u again

  • All times are GMT -7. The time now is 10:41 PM.