Furnace blower works, but no heat

Discussion in 'Heating / Cooling Systems' started by rt749, Sep 28, 2012.

  1. rt749

    rt749 New Member

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    Aug 26, 2012
    1997 Coleman Fleetwood Bayport. Owned it for a year. Slowly working on getting all of the parts and pieces to work right.

    I need some more help! Since I installed my new converter and new battery I can get the furnace blower to work, but no heat. There is a pilot that I assumed was for the refrigerator. I can light it, but don't see anything that resembles a furnace burner.
    We are planning to try winter camping, but I think the furnace will be a real necessity.

    Thanks for any help you can give me.
     
  2. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

    14,372
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    May 20, 2008
    Seattle, Washington
    Neither the furnace nor the fridge have pilot lights. You are probably lighting a pilot light for the water heater. Or, you may be lighting the propane flame for the fridge. That isn't a pilot light because it does not ignite a bigger flame. It is the entire heat source for the fridge when on the propane option.

    The furnace has an electronic igniter. First, be sure the propane is on and that the lines have been bled of air by running the stove for a few minutes. Second, be sure the On/Off switch on the thermostat (different lever than the temerpature setting lever) is set to On. Third, check under the metal furnace grille to see if there is a reset switch and if so, be sure it is set to On. If all of these things are OK and it still won't light, check the sail switch.
     
  3. Team cmk

    Team cmk Member

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    Jul 8, 2012
    UT - I'm curious, where is/what is a sail switch.
    Thanks
     
  4. Unstable_Tripod

    Unstable_Tripod Well, there's your problem!

    14,372
    9
    May 20, 2008
    Seattle, Washington
    Inside the furnace housing. The air from the fan moves it to make an electrical contact. Without this contact the gas valve will not open. It is a safety system.

    HERE is an example of one on ebay.
     
  5. mnebinger

    mnebinger Livin' The Dream!

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    Jul 22, 2012
    A sail switch is used to turn the propane on inside the furnace.

    Here's how it works:
    1. Thermostat calls for heat.
    2. Blower fan comes on.
    3. Once the sail switch is "blown" by the air flow of the blower fan, the electronic igniter starts clicking and the gas valve opens. Then you here a whoosh as the burner lights.
     
  6. rt749

    rt749 New Member

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    Aug 26, 2012
    Thanks Unstable! It must be the pilot for the refrig, because I don't have a water heater.

    I seem to be on the right track and will try the other things you suggested. Still not really sure where the sail switch is, but I think I have seen all of the other things you mentioned. I can't find a word in my owner's manual about the furnace.
     
  7. freenaz

    freenaz Member

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    Jun 7, 2011
    The furnace probable has its own manual and won't be in the owners manual.
    Make sure the thermostat is on and set high enough to start the furnace.
     
  8. smit1088

    smit1088 Well-Known Member

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    Mar 15, 2011
    Stillwater, MN
    Make sure your polarity to the furnace (and the rest of the camper) is correct. If the battery is hooked up backwards (Black is positive and white is negative on Coleman factory harness) the fan will run backwards and never let the sail switch turn the gas on.
    I know this from a cold evening.
    Good luck.
     
  9. rt749

    rt749 New Member

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    Aug 26, 2012
    Thank you for all of your suggestions! I hope I am closing in on this.

    Furnace switch is ON.
    Thermostat turned all the way up
    Propane on and lines bled by running stove
    Furnace blower comes on and blows strongly, but no heat
    I hear a sound which I think may be the burner trying to light, but nothing happens.

    Battery is disconnected in an attempt to make the low voltage alarm quit beeping, but no luck there.

    Sail Switch? There is also a 5 amp fuse in there?
     
  10. rabird

    rabird Howdy!

    6,128
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    Mar 3, 2006
    TX
    Lots of possible causes.
    see page 28, then 22-28
    http://bryantrv.com/docs2/docs/hflameservice.pdf

    I believe I'd check for voltage at the gas valve while it is attempting to light.

    Don't believe it is recommended but have read that folks give their furnace a whack from time to time!!!
     
  11. rt749

    rt749 New Member

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    Aug 26, 2012
    Thank you so much for the link to the manual. I am not there yet but feeling more positive that I can get to a warm place!
     
  12. freenaz

    freenaz Member

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    Jun 7, 2011
    "Battery is disconnected in an attempt to make the low voltage alarm quit beeping, but no luck there."

    Are you referring to the LP detector as the low voltage alarm? If so then the furnace will not light because it is detecting LP. The LP detector could have a bad or dirty sensor.
     
  13. rt749

    rt749 New Member

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    Aug 26, 2012
    Reasonably certain now (finally) that the lp detector was bad. I have removed it and will replace. I could not smell any LP, but that may be the only logical solution. Removing it resolved the beeping! I have not yet tried the furnace.

    Thanks for your suggestions. I will let you all know when (if?) I get it resolved.

    :)
     
  14. ChocoChock01

    ChocoChock01 On the road aagaain See Rallies below;

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    Mar 7, 2012

    Is there a test for either the Sail Switch or the Igniter to narrow down the defective item?
     
  15. rabird

    rabird Howdy!

    6,128
    85
    Mar 3, 2006
    TX
    I'll suggest a volt meter to probe the gas vale at the appropriate time. If the gas vale is getting power then the relay, sail and limit switch 'passed'. The gas valve's solenoid coils resistance can be measured.

    Various service manuals
    http://bryantrv.com/docs.html#furnace
     
  16. Travelhoveler

    Travelhoveler New Member

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    Mar 8, 2011
    Make sure the battery is well charged. A furnace will not ignite if the fan is not blowing hard enough.
     
  17. Sun Valley

    Sun Valley "The Rain King"

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    Aug 11, 2007
    Saint Louis, Missouri
    Re: Re: Furnace blower works, but no heat

    I'm thinking the same thing. Sounds like you may not have enough power to activate the sail switch.
     
  18. ChocoChock01

    ChocoChock01 On the road aagaain See Rallies below;

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    Mar 7, 2012
    Atwood Furnace Troubleshooting:



    BLOWER RUNS - BUT FAILS TO IGNITE
    Low Voltage/High Voltage--------------------------Correct power supply.*
    12 volt polarity reversed----------------------------Correct polarity.*
    Furnace grounding wires not secure ------------Clean and secure grounds established*
    Gas valve defective ----------------------------------Replace valve or valve coil, depending on problem encountered.
    Gas pressure incorrect------------------------------*Set pressure to a minimum of 11˝ W.C. with all appliances running.
    (Replace regulator if not obtainable).
    Limit switch defective or wire off ----------------Reconnect wire or replace.
    Sail switch defective or wire off ------------------Reconnect wire or replace.
    Burner orifice blocked ------------------------------Clean main burner orifice or replace.
    Combustion air wheel loose ----------------------Reposition and tighten.
    Burner head adjustment----------------------------Reposition and tighten. Adjust burner according to furnace
    specifications.
    Exhaust blocked --------------------------------------Clean exhaust.*
    Air intake restricted----------------------------------Clean air intake.*
    Broken or loose wire --------------------------------Replace or tighten*
    Motor running slow --------------------------------Check voltage first. If 12 VDC while running, replace motor.*
    Pilot orifice plugged --------------------------------Clean or replace orifice
    Thermocouple defective ----------------------------Replace thermocouple
    Pilot assembly defective----------------------------Replace pilot assembly
     

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