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Old 04-30-2019, 10:18 AM   #21
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Bama, it's confusing Steve as well about whether it runs or not. Steve told me about the control module up in the ac and I found it.

yep I knew about the cool down time, but the issue is it won't cool down. In fact i hear the gas valve solenoid re-open a few times after I disconnect the jumper and the heat increases out of the vent in the main area. It's like the little engine that could and doesn't want to quit.

The thing that is buried is the furnace itself. The entertainment center is built over it with no opening large enough to remove it. Can I attach pictures on here?



Quote:
Originally Posted by Bama Rambler View Post
I have to say I'm a bit confused by what you've been describing. Once you unhook the furnace control wires from the thermostat, anything you do to the thermostat won't affect the furnace. Also, once you jump the furnace wires together it will continue to run until you disconnect the jumper. Again nothing you do to the thermostat will stop it from running.

Keep in mind that once you disconnect the jumper (or the thermostat relay opens) it takes a few minutes for the furnace to cool down and shut off. It won't stop immediately.

Another thing that bothers me is that you said "I am trying to figure out how to get at it. It's buried in built in entertainment center." the control box should be in the return air section of the A/C.

Can you post some pics of the control box and the thermostat?
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Old 04-30-2019, 10:37 AM   #22
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I understand now that you were trying to get at the furnace itself, because it's buried in the entertainment center.

You can post pictures on here. It's pretty easy if you use the advanced reply instead of the quick reply button.

Let me make sure I understand what's going on.
When you jump the furnace wires (red & white) together the furnace will start running?

When you disconnect the jumper the furnace won't stop running until you remove the fuse?

Basically the same thing happens when the wires are hooked to the control box and you use the thermostat? The furnace won't stop running until you pull the fuse?

Is that basically true?

If so then I suspect that you have a bad control board on the furnace.
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Old 04-30-2019, 10:46 AM   #23
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"Let me make sure I understand what's going on.
When you jump the furnace wires (red & white) together the furnace will start running?"

If the t stat is in off position whether jumpered or not and the fuse reinstalled the furnace will run for a min and turn off.

"When you disconnect the jumper the furnace won't stop running until you remove the fuse? "

When the t stat is in the furnace position, yes it will not stop. It will also not stop if I change it to the off position. I have to pull the fuse to get it to quit.


So pretty much if tstat in off it wont run for than a min no mater if jumpered or not. When t stat in furnace position it will run and not shut off no mater if jumpered or not or if turned off at t stat. Can only shut off by pulling fuse.


Quote:
Originally Posted by Bama Rambler View Post
I understand now that you were trying to get at the furnace itself, because it's buried in the entertainment center.

You can post pictures on here. It's pretty easy if you use the advanced reply instead of the quick reply button.

Let me make sure I understand what's going on.
When you jump the furnace wires (red & white) together the furnace will start running?

When you disconnect the jumper the furnace won't stop running until you remove the fuse?

Basically the same thing happens when the wires are hooked to the control box and you use the thermostat? The furnace won't stop running until you pull the fuse?

Is that basically true?

If so then I suspect that you have a bad control board on the furnace.
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Old 04-30-2019, 11:16 AM   #24
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I think you may have more than one thing going on here. please try to post some pictures of the box and the wiring.

I also think you may not have the right wires to the furnace.
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Old 04-30-2019, 11:52 AM   #25
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This is a picture of the box in my camper. I disconnected and jumpered the two single wires on the left of the box.
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Old 04-30-2019, 12:07 PM   #26
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You picked the two wires that should be the control wires to the furnace, but if that were the case then the thermostat couldn't possibly have anything to do with the furnace with those unhooked. I think you're going to have to trace the wiring down.

Post some pics of your actual box and wiring whenever you can. Looks like they may have some wiring swapped, or something shorted, or both.
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Old 04-30-2019, 03:29 PM   #27
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Ok here are the pics. Shows the box and connections and the furnace and lack of access.

I did use my dvm and when I probed the two wires I did a continuity, so unless it has that by design at the furnace control board the two wires are shorted together.

To test this I need to make a jumper from the ac control to the furnace control, but there lies the problem of how to get at the furnace. I did send an email to Coachmen today with info I had and requested the build sheet and how to remove the furnace if it needs to be replaced.
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Old 04-30-2019, 03:42 PM   #28
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I’m going to bet that you will need to remove the furnace from the outside. From the pic there does not seem to be any other way.
Further reading of the suburban manual shows that the outer cabinet can stay in place, the furnace guts remove from the outside after removing the vents and cover.

Just a couple of random thoughts here.
Does the unit have any 120 VAC power control or shedding devices that may be interacting.
After all you have done and tested the issue points to the furnace but the interaction of the tstat when the red/white wires are disconnected makes no sense.

Looking at the Suburban furnace prints (there are many different versions) some have a time delay relay, the no turn off when tstat opens would point to that as the issue.
As suspected one of the tstat wires is supplied +12 volts from the furnace, the other returns the +12 to a relay to activate the ignition sequence.

I have to suspect the furnace control board as the issue with your system.
It may be intermittent enough that when your doing your testing you get false results that appear to point to the AC control.

Try testing the furnace output on the AC control (the 2 quick connects) that they are closing correctly (zero ohms) when the tstat calls for heat and open (infinite ohms) when the tstat is not.
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Old 04-30-2019, 04:27 PM   #29
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Steve there is no door on the outside, just the inlet and outlet plate.

No idea on the 120VAC to the furnace, there is nothing listed on the breaker panel for the heater.
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Old 04-30-2019, 04:38 PM   #30
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Quote:
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Steve there is no door on the outside, just the inlet and outlet plate.

No idea on the 120VAC to the furnace, there is nothing listed on the breaker panel for the heater.
Agree, not what Steve is referring to.
Never seen a outside door for the furnace, just the vents.
Now if you were referring to a water heater, then yes.
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Old 04-30-2019, 05:13 PM   #31
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Ok I contorted and got my arm into the opening by the furnace and found the wire harness. Found the two wires from the control module and disconnected them and jumped the two blue wires coming out of the furnace and voila the blower came on and then a little later the igniter kicked in and I had heat. Let it run for a bit then disconnected them and the burner shut off and the blower about a min later so the culprit are the wires between the ac control module and the furnace.

That being said, I need to research running new wiring in RV walls and ceilings.
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Old 04-30-2019, 05:17 PM   #32
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Steve there is no door on the outside, just the inlet and outlet plate.

No idea on the 120VAC to the furnace, there is nothing listed on the breaker panel for the heater.
Eveything is right there . fan motor , pc board etc . just need to remove furnace cover that you see in your pic. should be able to get to the t-stat wires very easy with out removing the furnace
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Old 04-30-2019, 05:20 PM   #33
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Quote:
Originally Posted by volliefd View Post
Ok I contorted and got my arm into the opening by the furnace and found the wire harness. Found the two wires from the control module and disconnected them and jumped the two blue wires coming out of the furnace and voila the blower came on and then a little later the igniter kicked in and I had heat. Let it run for a bit then disconnected them and the burner shut off and the blower about a min later so the culprit are the wires between the ac control module and the furnace.

That being said, I need to research running new wiring in RV walls and ceilings.
made another post before seeing this one . you can always install a new t-stat just for the furnace close to where the furnace is . in the same cabinet just higher up
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Old 04-30-2019, 09:56 PM   #34
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Steve there is no door on the outside, just the inlet and outlet plate.

No idea on the 120VAC to the furnace, there is nothing listed on the breaker panel for the heater.
Interesting, On mine there is a metal panel held on by 4 screws and the vent plate is attached to that.
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Old 04-30-2019, 11:34 PM   #35
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I have a Freedom Express and mine is in the typical location under the dinette. But I will offer one bit of advice. All of my LP lines were also attached to the floor and if the line went through more than one level like the fridge line and oven line did, attached to each level. They are attached with a black nylon tie-wrap that has a screw eye which was screwed into the wood. I think they do this to keep the LP lines from falling out of place before the appliances are installed. My furnace also had one. So I would expect your line to also be tie-wrapped somewhere. It may or may not matter depending on what you have to do go remove it, but I wanted you to be aware of that possibility.

Mine were all like this (except in black)

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Old 05-01-2019, 05:35 AM   #36
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Ok I contorted and got my arm into the opening by the furnace and found the wire harness. Found the two wires from the control module and disconnected them and jumped the two blue wires coming out of the furnace and voila the blower came on and then a little later the igniter kicked in and I had heat. Let it run for a bit then disconnected them and the burner shut off and the blower about a min later so the culprit are the wires between the ac control module and the furnace.

That being said, I need to research running new wiring in RV walls and ceilings.
Great that you found the problem. Running new wires from point A to B will unfortunately involve a lot of work.you should be able to get prints from FR showing the intended routing of the wires, it may help you to find the best route.
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Old 05-01-2019, 07:09 AM   #37
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I found where they go. The wires go back to the wall cavity that the thermostat is located and then go down past the fridge and then under the floor and across the floor and then back up into the wall behind the furnace. So I get to see today if I can unbolt the underbody cover and see if I can see them. We head back out next Friday.

I tried to run through the ceiling but the a/c duct blocks the path across the room to move laterally towards the wall the furnace is on.
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Old 05-01-2019, 09:49 AM   #38
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Found the two wires from the control module and disconnected them and jumped the two blue wires coming out of the furnace and voila the blower came on and then a little later the igniter kicked in and I had heat.
So you have blue wires leaving the furnace and a red & white wire at the control box. Did you find where they changed colors?

I suspect you have some mis-wiring either in the wall or at the control box.
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Old 05-01-2019, 10:30 AM   #39
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Yep they change to red and white as soon as the wiring pigtail from the furnace ends.
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Old 05-01-2019, 10:51 AM   #40
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That's good in a way.

If you disconnect them at both ends can you;
1) Check for continuity of each wire?
2) Check each wire to see if it's shorted to each other?
3) Check each wire to see if it's shorted to ground?
4) Check each wire to see if you get +12 volts on it?
5) Check each wire to see if you get any AC voltage on either one?
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