Need help with Atwood 7916 II not working

Discussion in 'Introduce Yourself' started by Todd Porter, Sep 4, 2017.

  1. Todd Porter

    Todd Porter New Member

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    Dear Popups,
    I am working on my brothers camper furnace, Atwood 7916 II. I'm not sure how old it is but would guess 90's era. I have replaced the ignitor (3 prong) Gas valve, and most recent the control board. Today after installing the control board that didn't fix the problem, I took the heater out and cleaned the dust out of the fan area. I also replaced the sail switch today. The stove in the camper works, but no heater. The thermostat seems to be working because I can hear it click when I turn it up past room temp. I also replaced the 2 pronged nickel shaped device (switch of some sort?) located on the inside wall behind then control board. When I turn the red switch on and turn the thermostat up I hear a click, after a moment the fan comes on, then about every 15-20 seconds I hear one click, (as if it is trying to start.) I also blew out the gas line today. There is a light behind the control board that blinks 3 times while the furnace is trying to start. I have also cleaned the burner and removed all the slight rust and made sure the holes are all open. I have read similar starting ignition problems on-line and I am leaning towards not enough gas pressure. Can the regulator be turned up? Can someone please rescue me from this frustrating problem?
     
  2. xvz12

    xvz12 Well-Known Member

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    I have this exact model in our pup, I've found that running the stove top for a few minutes to bleed any residual air out of the system before trying to light the furnace makes a big difference....If i don't do it, it takes FOREVER, many restart cycles, to get it to light. Secondly, are you sure you're getting at least a full 12 volts to the furnace? If the battery voltage is a little low, the fan won't spin fast enough to activate the sail switch.
     
  3. Todd Porter

    Todd Porter New Member

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    I have the unit plugged in to the 110V. The new sail switch did not have the big sail, just a narrow one. The sail switch did have lots of dust/lint around it. The squirrel cage was also full of lint. I will test the old sail switch and if it has continuity I will change it back. I have been lighting the stove and allowing it to run for a few minutes before attempting to light furnace.
     
  4. Todd Porter

    Todd Porter New Member

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    I changed out the sail switch back to the original one after it tested positive for continuity. I have 12.47V at the red wire. My ignitor wire has continuity. The only thing the relay (?) on the right side wall. It has a double black wire, double white, pinkish-red, and red wire going to it. At this point I think I'll order it. I bled the line until I could feel and smell gas out of the connector, then connected it, then ran stove burners for 2 minutes before turning on switch and thermostat. The fan started, and I could hear a click once in a while like it was trying to start. My brother said he could smell gas coming out the exhaust outside the camper. That relay could be it. If it doesn't transfer current to the ignitor to create a spark, its not doing its job. What say you?
     
  5. Paul ski bum

    Paul ski bum New Member

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    Hi there I'm supper new to this community and I had the same problem. I bought a westlake Colman camper used. The guy I bought it off of never used the furness. I looked at everything thinking you did. What I found is when i undid the union flare nut at the reg I had about a palum full of oil in my gas line. I took the the board out of the slot with it connected there is a little port just after the gas valve on the 90 going in to the burner you need a 1/4" Allan key to take it out. You need a monomitor that will read your gas pressure there is a 1/4" adapter you can put in there to read the gas pressure with the monomitor as the gas pressure coming in to the furness is under 1/2psi so we measure in inches of water colum. In the centre of your of your gas valve there is a set screw you can remove with a flat head screwdriver remove that cap with your monomitor plugged in to that port and your furness running you will see numbers pop up on your monomitor if you take the flat head turn in it clock wise it will adjust the pressure to your gas valve if your furness has fired you should be able to adjust gas flow. Also what I did chock off the exhaust on the out side 50% doing this alone may get your furness to fire as if your not getting enough gas it's all getting blown out of the heat exchanger chocking it off may get it to start. But it shouldn't be like that. I was talking to a guy at a rv repair place and that's what he told me to try that and that alone got my furness to fire. So I went camping this past weekend up in Rocky Mountain house in Alberta Canada it worked the first to nights but the 3ed night it did not work for me. I used foil tape to chock my exhaust. I got back on Monday Thursday after work I blow out my gas line with 5-10 psi of air with my compresser. To do this I unhooked my regulator and pulled the gas valve/burner out. Took the 3/8 fitting out the gas valve got a 3/8 90 and bushed it down to 1/8" hooked up a air shrater valve and blow the line out. Also what what I did as I had the burner out I tested the solonids on the gas valve with my Milwaukee 12v battery tool set I have. Hooked too wires one in each lead and hooked it up to the gas valve on each side. You should hear a click. Both sides worked. Hooked up both solinoids with the wires put the lead from my battery I heard a click. Now you should be able to blow through the gas valve as the valve are open. Be careful not to get your face in contact with the wires. You can also take the top port of the gas valve hook up a 3/8 nipple a 3/8 90 and use your bushing with air shrateor and with power to your valve you can blow it out using under 5pis. If your compresser has a regular on it. I did this and I put it all back together and now my furness works great. I think it was a combination of blowing my gas lines out 5-10 psi and blowing air through my gas valve. Now when my furness fires I can set my gas valve to up to 9" of water colum where before I was getting 1.5 also if you have a multie meater you should see about 20 olms of resistance on the valve if your testing the solinouds. Hope this helps. Like I said this is my first post. I'm a plumber by trade so have a bit of experience working on furness on homes. I wouldn't recommend anyone leaving there exhaust chocked off to run the furness. Any questions feel free to ask. Thanks.
     
  6. Todd Porter

    Todd Porter New Member

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    Thank You, I will get a manometer and test my pressure. What should the pressure be at? I've heard others say 11, between 9-11? I'll try to get a book recommendation. I shall return........the saga continues........lol
     
  7. Paul ski bum

    Paul ski bum New Member

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    On mine before I made the repair I was only getting like 1.75" of water colum which is like nothing that's with the furness burning the gas. After the repair I was getting 7" and adjusted it to 9" on the gas valve. Try chocking out the exhaust 50%with foil tap or something else and see if it fires.
     
  8. rabird

    rabird Howdy!

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  9. Douggro

    Douggro Active Member

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    The relay in question is a time-delay relay. If your blower fan is coming on and you're hearing the ignitor try to light the furnace, the relay is good.
    Focus on gas flow, good ignitor spark and a clean burner.
     
  10. Paul ski bum

    Paul ski bum New Member

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  11. Todd Porter

    Todd Porter New Member

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    I got a new time delay relay and it still doesn't work. I believe the old relay is good. I tried blocking 50% of the exhaust and could see gas coming out of the ignitor area. I'm just not getting spark. Still getting the lockout f 3 flashes. I'm taking the camper back to brothers and having him take the furnace to an RV place. We'll see what they say. I could of received a bad board, I don't know. I've done everything I learned to do. I have three good days into this thing and I need to get into a tree stand! I don't like leaving things, and can usually figure things out. Thanks for all your help. When or if this old furnace gets fixed I will post the problems found. I'm sure I overlooked something. IDK.
     

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