Blower Fan Cycling Every 20 minutes for 30 seconds
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  1. #1
    Join Date
    Sep 2011
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    The Deep
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    Blower Fan Cycling Every 20 minutes for 30 seconds

    Hi,
    Lennox G10D-100-1
    Problem is:Blower Fan Cycling Every 20 minutes for 30 seconds

    This is even with the heat off(stat on A/C) and the pilot unlit.

    I checked the limit switch, the point is on the pre-set mark,I moved it and saw the preset mark and put it back on it.

    This is a 4 wire Cam Stat switch 7 inch.

    It only has that one switch in the box.

    The blower switch is only Continuous or Auto, no Intermittant.

    The scenario for many years that I can remember is that the heat blows to temperature, shuts down then the fan would come on a few minutes after that for about 30 seconds, stop and that was it until it got cold and more heat was required.

    I did change the pilot and thermocoupler because of it leaking and not wanting to light for a long time,that is working ok except for it sounding like it is blowing in the Wind all the time.

    It there a Coil on the gas valve I can clean( I heard a guy say this but I think he was refering to the Evap on his A/C, He was refering to G10 also, there is probably a G10 A/C unit but I didn't check before posting.

    P.S.

    I did take the switch out, checked it and made sure it was clean and not hung up, moved the metal strips a little, the 2 small bolts were not loose or backed off, the magic marker marks are still there and the strips look like they match up with them.
    Before I took it out there the top screw was cocked up and not holding the top, the switch may have been off level and pointing upwards inside, I got it back in level and both screws correctly in.
    It did work for hours(did not come on for like 4 or 5 hours then did the 30 seconds again) This is now with the Pilot lit, it was also doing the 30 seconds every 20 minutes with the Pilot Lit before I took it out.
    It is not coming on for hours now instead of every 20 minutes.
    Will just the pilot get enough heat up in too trigger the fan and or is it coming on every 5 hours for 30 seconds normal, I can't spend 150 for this switch it is going to do the same thing.

    Thanks if you can help.

  2. #2
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    1,950
    Some of those Cam-stats have a heater circuit in them that brings the fan on like a time delay relay. If there is a short in the wiring you could be heating the Cam-stat and with nothing else the fan could cool it down in 30 seconds.

    Please note that just because it has 4 wires going to it does not mean that this control has a heater in it, it could be a fan/limit control, not a heater assisted fan control.

  3. #3
    Join Date
    Sep 2011
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    ////////

    The part Number is:
    CamStat FAL-7C-OIT-110-200

    The OIT can also be 01T, hard to tell.




    By the FAL(Fan Limit) 7C(7 inch) 200(limit), Just a educated guess, don't have a guess for the rest.

  4. #4
    Join Date
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    Quote Originally Posted by StuNut View Post
    The part Number is:
    CamStat FAL-7C-OIT-110-200

    The OIT can also be 01T, hard to tell.




    By the FAL(Fan Limit) 7C(7 inch) 200(limit), Just a educated guess, don't have a guess for the rest.
    I'll go with this instead:

    FAL(Fan Limit) 7C(7 inch) 110(On Temp) 200(limit)

  5. #5
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Is this furnace located in the attic or a hot location?
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  6. #6
    Join Date
    Sep 2011
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    Hi,
    No it is in the basement on blocks next to the water heater.

    Dry basement with sump pump, I put a pump in 5 years ago probably, it use to get water every 2 years or so coming up from under the slab, there could be some corrosion in there maybe??? Big maybe??

    Ever take one of the CamStat 7 inch with the 2 rods in it apart?

    I see the four screws.

    I looked in the chamber also and it looks good in there.
    Last edited by StuNut; 09-20-2011 at 05:34 PM. Reason: added

  7. #7
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    33,832
    G10? The Duracrack heat exchanger is probably split open if someone cares to look

  8. #8
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    Problem is:Blower Fan Cycling Every 20 minutes for 30 seconds

    This is even with the heat off(stat on A/C) and the pilot unlit.

  9. #9
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    Since there is no source of heat to legitimately start the fan, I belive that the fan swich is defective. Live with it or replace it. It is not a safety issue.
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

  10. #10
    Join Date
    Dec 2005
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    1,900
    Quote Originally Posted by StuNut View Post
    Problem is:Blower Fan Cycling Every 20 minutes for 30 seconds

    This is even with the heat off(stat on A/C) and the pilot unlit.
    Would you think it is best to call the technician out to check it rather than googling it on the net?

    This is the gas heater, which is also called exploding device. I am just concerning for your safety.

  11. #11
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    I've been a mechanic for around 30 years or so, I fix anything and everything, I am well aware of the danger and all that.

    I was just looking for some discussion about this, I am not a Parts Changer, I don't just change parts until I hit the jackpot and change the right one.

    I diagnose the problem and fix it with a Quality attitude.

    I don't need a "tech", I've worked with "Techs", I wouldn't let some "Techs" fix my bicycle. I'm not bashing any certain group of techs, I have been behind the scenes so to speak, the scene that the customer doesn't see, I've seen it, I don't know how some people get the jobs they have, they lie and talk a good game but can't back it up.

    The money isn't there to throw out the window either.

    I know you had no idea of this and it sounds like I took offense to your reply, but no offense taken.

    I am going to see if a supply store has the part and If they do I am going to take apart the one in the furnace, if I find something wrong and can get it to work I will.

    If I can't and cause damage to it I already know there is one waiting and I can go get it.

  12. #12
    Join Date
    Nov 2001
    Location
    east kansas
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    8,024
    Quote Originally Posted by StuNut View Post
    Problem is:Blower Fan Cycling Every 20 minutes for 30 seconds

    This is even with the heat off(stat on A/C) and the pilot unlit.

    No, the problem is:


    Quote Originally Posted by BaldLoonie View Post
    G10? The Duracrack heat exchanger is probably split open if someone cares to look
    Beware of advice given by some guy on the Internet.

  13. #13
    Join Date
    Sep 2011
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    A split in the exchanger would cause the fan to do this when there is no source of heat?

    Is this what you are saying and can you tell me more about this?

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