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Author Topic: Furnace not working  (Read 1007 times)

Peteyboy

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Furnace not working
« on: October 12, 2017, 11:39:03 AM »
Took the MH to a local shop to fix the furnace on our rig as it is completely unresponsive to the thermostat.  The little flame icon appears when you ask for heat, but no ignition, fan, nothing.  They just called to say they can't figure it out.  Will probably take it to the factory when I can, but does anyone have any ideas in the meantime ?  Can a separate thermostat be installed just for the furnace ?  BTW,,, the shop said they got the furnace to run from directly at the unit and it ran that way perfectly.
« Last Edit: October 12, 2017, 11:47:35 AM by Peteyboy »
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

afchap

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Re: Furnace not working
« Reply #1 on: October 12, 2017, 12:03:29 PM »
Yes, you could have a separate thermostat just for the LP furnace. (My coach has two LP furnaces, one with it's own t-stat and one linked to the heat pump in the main t-stat.) Having a separate t-stat would not allow the heat pump lock-out mode that kicks on the LP furnace to work, but that wouldn't be a big deal in my opinion.

I am puzzled as to why the shop can't "figure it out." I would think that any competent shop would be able to determine whether or not the t-stat is sending the required signals to the furnace. It is possible the t-stat is defective, but they need to do some routine trouble shooting before starting to throw parts at it. I guess it is good that they admitted they can't figure it out rather than starting to do solutions that cost you $$$ and may or may not fix it!
« Last Edit: October 12, 2017, 12:06:01 PM by afchap »
Paul ... (KE5LXU), was fulltimin', now parttimin'...
'03 Winnebago Ultimate Advantage 40e
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Peteyboy

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Re: Furnace not working
« Reply #2 on: October 12, 2017, 12:42:52 PM »
Thermostat was replaced this summer for an A/C problem, so chances are that it is good. They did say that the thermostat signals are not reaching the furnace.  They said something about a secondary thermostat being in the system somewhere,,,, ??
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

QZ

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Re: Furnace not working
« Reply #3 on: October 12, 2017, 02:16:17 PM »
If they cant figure it out they shouldn't be touching it. I would back track. They may have miss wired the thermostat when they worked on it last time. There are not that many wires controlling it so if a broken wire is suspected, bypass it. They already answered their own question and proved it when they jumped it directly at the furnace. I dont want to call them idiots but.....            What is the  model number.

Peteyboy

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Re: Furnace not working
« Reply #4 on: October 12, 2017, 03:05:39 PM »
It is a Suburban SHD = 2542Q
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

QZ

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Re: Furnace not working
« Reply #5 on: October 12, 2017, 03:20:23 PM »
This link shows your model but the schematics are not showing your dual output furnace.

http://www.bdub.net/manuals/Suburban_Service_Manual.pdf
« Last Edit: October 12, 2017, 04:20:33 PM by QZ »

QZ

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Re: Furnace not working
« Reply #6 on: October 12, 2017, 03:53:11 PM »
What does your thermostat look like? Does yours control the heat and ac on the same thermostat?

Is it like this?

« Last Edit: October 12, 2017, 04:00:57 PM by QZ »

Peteyboy

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Re: Furnace not working
« Reply #7 on: October 12, 2017, 03:55:58 PM »
Yep,,, thermostat controls both a/c's and the furnace.  Will try to work thru the manual but I am really a plug and play kinda guy, or if a wire is broken or disconnected I am a genius.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Gary RV_Wizard

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Re: Furnace not working
« Reply #8 on: October 12, 2017, 03:59:54 PM »
If your furnace works off the same thermostat as the a/c, chances are the heat-needed signal goes through the a/c zone controller. Almost guaranteed it does if you have heat pumps or multiple heating/cooling zones in the RV. Odds are both of those are true in your coach.

The signal to the furnace is simple - just +12v on a wire that [eventually] reaches the furnace. But if the wire goes to the zone control first, it may have been disconnected there, or conceivably the zone control board is faulty (rare).

What thermostat is it, and do you have multi-zone and/or heat pumps?
Gary
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Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Peteyboy

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Re: Furnace not working
« Reply #9 on: October 12, 2017, 04:08:47 PM »
Thermostat is an RV Comfort.ZC.  Yes it controls everything with 2 zones. but the gas only works off the front a/c.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Peteyboy

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Re: Furnace not working
« Reply #10 on: October 12, 2017, 04:10:19 PM »
I did uncover both a/c units and both control boards have everything connected.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Peteyboy

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Re: Furnace not working
« Reply #11 on: October 12, 2017, 04:15:44 PM »
And yes,,,, both a/c units are heat pumps,,,, thankfully.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

QZ

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Re: Furnace not working
« Reply #12 on: October 12, 2017, 04:26:51 PM »
I'm not finding a great link but this one seems to also show a control box. Since yours is dual heat it may be relevant.  The control box looks like it ties into the generator start system.

http://www.rvtechlibrary.com/heatair/RVP_tstat_install.pdf
« Last Edit: October 12, 2017, 04:43:10 PM by QZ »

QZ

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Re: Furnace not working
« Reply #13 on: October 12, 2017, 04:42:55 PM »
Looks like a fuse in that thermostat




FUSE
The thermostat is equipped with a replaceable fast acting 2-Amp fuse located on the base of
the thermostat.  The fuse is designed to “open” if the appliance is mis-wired or there is a short
in the system.  If the fuse opens, the cause of the failure must be located and corrected before
the fuse is replace
« Last Edit: October 12, 2017, 04:45:24 PM by QZ »

Peteyboy

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Re: Furnace not working
« Reply #14 on: October 12, 2017, 04:52:08 PM »
I'm not finding a great link but this one seems to also show a control box. Since yours is dual heat it may be relevant.  The control box looks like it ties into the generator start system.

http://www.rvtechlibrary.com/heatair/RVP_tstat_install.pdf
The control board does have terminals marked generator.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Peteyboy

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Re: Furnace not working
« Reply #15 on: October 12, 2017, 05:01:03 PM »
Looks like a fuse in that thermostat




FUSE
The thermostat is equipped with a replaceable fast acting 2-Amp fuse located on the base of
the thermostat.  The fuse is designed to “open” if the appliance is mis-wired or there is a short
in the system.  If the fuse opens, the cause of the failure must be located and corrected before
the fuse is replace

Took the original thermostat apart and if there is a fuse in there it is not like any fuse I ever saw.  Everything on the board is soldered into the board for sure.  The replacement thermostat looks exactly like the original.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

QZ

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Re: Furnace not working
« Reply #16 on: October 12, 2017, 05:01:20 PM »
The control board does have terminals marked generator.

Look for a fuse on the base of therm. Check it with a low power test light or ohm meter. You mentioned your capabilities early. A visual inspection is a first step and then you start a process of troubleshooting. Most important is to not use any jumpers or accidentally shoot power to a circuit that blows out a control board or something. There is a point where you need to realize your limitations and maybe find a different repair facility.


Edit: Ok we were both typing. Is there a little door or plate or anything on the bottom?

Peteyboy

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Re: Furnace not working
« Reply #17 on: October 12, 2017, 05:05:38 PM »
Yep,,, I am  definately at my limits, so before I put 110 volts to a 12 volt system I will put my hands up.  Just have to stay above 40 degrees this winter which usually isn't too difficult in south Texas or Arizona.  Thank you for all the ideas and imput.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

QZ

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Re: Furnace not working
« Reply #18 on: October 12, 2017, 05:09:28 PM »
Yep,,, I am  definately at my limits, so before I put 110 volts to a 12 volt system I will put my hands up.  Just have to stay above 40 degrees this winter which usually isn't too difficult in south Texas or Arizona.  Thank you for all the ideas and imput.

Dont give up yet. :) I was looking for a pic of the fuse location and only found this so far. Looks like it resets the system too.

http://www.winnieowners.com/forums/f259/rv-comfort-zc-issue-280415.html

QZ

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Re: Furnace not working
« Reply #19 on: October 12, 2017, 05:12:27 PM »
Do you know how to properly program it? I know some modern gadgets will wear ya out until you learn it then we dont have a problem for a long time and forget it. Like my cameras and other stuff with too may features.

QZ

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Re: Furnace not working
« Reply #20 on: October 12, 2017, 05:15:47 PM »
Some problems can end up being something real silly. Read this and go back to reset and reprogram.  BUT I dont want you to end up with nothing either......so dont reset it if you cant program it.

http://www.rvforum.net/SMF_forum/index.php?topic=84810.0

http://www.rvforum.net/SMF_forum/index.php?topic=38922.0

Read through these posts as merc talks about checking connections in the control box and an green led coming on. Be careful of 120 volts from shore power possibly.

http://www.rvforum.net/SMF_forum/index.php?topic=38922.0
« Last Edit: October 12, 2017, 05:30:22 PM by QZ »

Peteyboy

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Re: Furnace not working
« Reply #21 on: October 12, 2017, 06:42:37 PM »
Don't know how to reprogram it but did check control boxes and everything looked attached and fine.  Didn't see any LED's in the boxes though.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Ernie n Tara

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Re: Furnace not working
« Reply #22 on: October 13, 2017, 08:31:51 AM »
I have the same thermostat.  On a couple of occasions it has gotton lost or lost its program. If I remove the thermostat from the wall and unplug it or a few seconds, it resets to normal.


Ernie
Ernie 'n Tara

2011 Winn Journey 34y
2012 Jeep Rubicon - Dozer (orange - kinda)
2006 Jeep Wrangler

Alfa38User

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Re: Furnace not working
« Reply #23 on: October 13, 2017, 08:32:55 AM »
If the thermostat was replaced recently, it may not be unusual to find it defective from the beginning, especially if the furnace start was not tested at the time of installation. I went through two new RV Comfort thermostats that had defects before getting a third good one several years ago. Fortunately they were all on warranty.
Stu
Montréal, Canada 🍁
Snowbird, Naples Florida
Alfa Gold 38 (2000) 5ver (parked!)

"Of course I talk to myself, sometimes I need expert advise!!!"

Peteyboy

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Re: Furnace not working
« Reply #24 on: October 13, 2017, 10:06:09 AM »
I have a HVAC tech who mainly works on home units coming out.  At least he understands how these things are supposed to work.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Gary RV_Wizard

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Re: Furnace not working
« Reply #25 on: October 13, 2017, 10:40:40 AM »
It's simple enough to check for the +12v signal on the heat line from the t-stat. If it does that, the t-stat is ok. If not...
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Gary RV_Wizard

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Re: Furnace not working
« Reply #26 on: October 13, 2017, 10:53:54 AM »
There are a couple variations of the ZC model thermostat, e.g. an 83xx series and a 93xx. The 93xx uses an infrared remote sensor, so I'm guessing the 83xx is wired.  In any case, I believe the white wire from the t-stat is the heat signal in all of them, and also the earlier HC model.

83xx manual:
http://www.dyersonline.com/downloadfile/download/aitfile/aitfile_id/3465/
93xx manual:
http://www.rvcomfort.com/pdf_documents/1976410_copy.pdf
« Last Edit: October 13, 2017, 10:56:44 AM by Gary RV_Wizard »
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Peteyboy

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Re: Furnace not working
« Reply #27 on: October 13, 2017, 12:21:25 PM »

Thanks Gary,,, hopefully the tech knows all that stuff.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Peteyboy

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Re: Furnace not working
« Reply #28 on: October 18, 2017, 07:02:46 AM »
It appears that one of the circuit boards on the furnace is malfunctioning and when I looked for circuit boards on Amazon, it was the first one that popped up.  That might tell you something.  Will report when we get it installed.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

Peteyboy

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Re: Furnace not working
« Reply #29 on: October 20, 2017, 07:41:18 PM »
Well,,, plugged the new circuit board in and, you guessed it, didn't fix the problem.  Really has the tech puzzled as power comes in to the board, but does not come out,,, same as the old one.  What are the chances of two boards being bad in exactly the same way.  Troubleshooting specs say, if this occurs, the board is bad.  He is going to try to talk to someone at Suburban next week to see if he can get some advice.
Pete & Sandy
2015 Itasca Suncruiser 37F
11 CRV

 

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