2000 fleetwood bounder

[bouncybounder]

Hello, my Rv has two furnaces. One in the front under the refrigerator and the second one is around where the shower is located. The fan works on both the front and the back furnaces. The front furnace puts out heat but not the rear one. I don't think it is a problem with the thermostat or the control module for it....It could be an issue with the propane not getting to the furnace or maybe the furnace needs to be repaired? Both run on propane which I know works. 

Any tips or ideas you guys have might be helpful. Does anyone know of valves/switches that need to be checked? Or the best way to access the furnace?

Edit: The fan makes a loud screeching sound when it fist starts and then after a  minute or so goes quite and the vent continues to blow cold air.

Edited September 9, 2019 by bouncybounder

[Kirk W]

2 hours ago, bouncybounder said:

Any tips or ideas you guys have might be helpful. Does anyone know of valves/switches that need to be checked? Or the best way to access the furnace?

Edit: The fan makes a loud screeching sound when it fist starts and then after a  minute or so goes quite and the vent continues to blow cold air.

Welcome to the Escapee forums. I'm sorry that you have problems to cause you to post but we are still happy to have you join us!

In anylizing what you have told us I have some pretty strong suspicions about the problem, but will deal with your questions in order. There are several possibile causes as the propane supply valves occasionally fail, there is a high temperature linit device that can fail, and there are a few other possibilities such as a failed ignitor probe, but the thing that I suspect most likely is what is called the sail switch. The sail switch is actuated by a vane that is located in the air flow path to the combustion chamber and it prevents the ignitor from sparking unless it is pressed to the point of closing the sail switch to make sure that your furnace has enough air movement from proper combustion before it starts the flame. If the switch does not close in a proper span of time after the system attempts to light the propane it will shut off the propane and in many models of furnace the blower will continue to run until the inside thermostate is set low enought to stop calling for hear or turned to off to allow things to reset. The fact that your blower is making a screeching sound makes me believe that the fan has not come up to speed and so the sail switch is not closed and thus no heat. The time to get the sail switch closed to get heat is usually under 30 seconds so it probably has stopped trying by the time your blower is up to proper speed and supplying enough air movement to operate safely. 

As to how to service it, that depends on both the make and the model. Atwood furnaces and some Suburban furnaces have an outside access panel that can be opened to service them, but most models of Suburban require that you remove them from the RV to gain access to the interior and work on it. It would help us to know what make and model of furnace you have but most likely it is one of the two brands that I suggested. If you know what make and model you have, you can go to the website of Bryant RV and download a copy of the service manual which may help. 

[bouncybounder]

Thanks for the information. 

The fan is running better now, and not making any noise with a good flow rate. It still doesn't put out heat.

I have a atwood furnace so I can take it apart from the side. 

What I did was take it apart from the side and see if I could access the inside of the furnace fan. I was able to loosen the panel that covers the sail switch. I couldn't get the cover panel all the way off because some wires were in my way.   I then reached in to see if the sail switch was stuck or something. I didn't feel anything wrong with the switch. I couldn't tell for sure if the switch was working or not though.

I am thinking it might be something wrong with the igniter or something in that area? 

Also this might not be reliant but when I lite the burners in the rv they pulse rapidly. It is about a ten percent pulse every half second. It is most easy to see when the burners are on high. 

It looks to me like the previous owner may have tried to repair the furnace before as a part of it was bent. 

Edit: no sound of a spark or propane smell when the is activated. No smell of propane. Small LED light on one the circuit board within the furnace. It does not turn on. 

Edited September 21, 2019 by bouncybounder

[oldjohnt]

Bounder, if the fan comes up to speed and blowing a good volume of air (despite the early squeaking) I doubt if the sail switch is the problem but hey Im not there to observe and it may well be. Once those fan bearings start that high pitch death shrill they dont cure themselves and get worse when its cold.

 Once the t stat calls for heat and after a delay iffffffffffff the sail switch makes up and ifffffffffffff the high temp limit switch is closed (seen them go bad and open) voltage is sent to the control board, the gas valve opens and the boards HV spark coil/transformer deliver a HV spark to lite the gas. If you are there and listen carefully after the delay you can hear the gas valve open (clunk) and the ignitor tip go tic tic tic tic as it sparks to lite the gas. If the fan is on and there's sufficient air to close the sail switch but the gas valve fails to open I suspect low voltage (see if it helps if you're plugged to shore power) or the limit switch is open or the control board is bad. If the gas valve does open (heat or feel it clink) but it doesn't light the control board or its HV coil/transformer is bad or the ignitor tip has a problem. If you can hear or see the HV tic tic tic spark but it doesn't light I suspect the ignitor tip is bad (shorting to ground versus the gap at the gas) or there's a bad ground. I have had them fail to due a hairline crack or carbon trace OR EVEN AS MENTIONED THERES A BAD GROUND WIRE OR CONNECTION. Check the ground on the tip assembly and the little sheet metal mount screws for rust or corrosion.

 It has to get voltage to the board (cant if limit switch is open or sail switch doesnt close) then the board has to work and open the gas valve then the boards HV coil/transformer has to deliver the HV spark pulses then the ignitor tip has to be good WITH NO BAD GROUNDS OR WIRES OR A CRACK and they can also get out of adjustment.

Maybe its just a bad ground or low voltage or the ignitor  tip is bad

Have to run out of time I will check back later 

 

 John T

       

  

Edited September 21, 2019 by oldjohnt

[bouncybounder]

There is an on off switch for the fan. I tested the voltage with the fan running at it was at a constant thirteen volts. I don't hear any clicking or see or smell any propane. I am guessing that the start process is being stopped before the gas is turned on or a spark is created in the furnace. 

 

I am going to try to check if power is getting to the silicon board/control panel? in the furnace next. 

[bouncybounder]

I figured it out...there was a silicon computer panel to the left of the main motor. Lots of dirt and condemnation had gotten on the back of the panel. I think this was causing a short circuit somewhere on the board. There is a green/red led light on the panel. Once I took out the panel and cleaned off the back of it the green/red light on the panel went on and the furnace lit fine. That or it may have been the grounding wire or one of the other wires on the panel wasn't connected correctly. 

Anyways it is working now and I'm happy. 

Thanks for the replies.

[oldjohnt]

CONGRATULATIONS and thanks for the feedback. Yep any shorting path or a bad/loose/corroded connection or a resistive ground may have been the culprit. My experience with a squeaking fan, however, is they get worse over time and especially when its cold and its most needed grrrrrrrrrrrrrrrrr.   Another thing that can mess up the control board operation is corrosion on the flat ribbon cable connector (if yours even has that??) and sometimes a simple unplug and re plug can make them work again. I usually clean/shine the flat brass looking contact strips with a soft pencil eraser.

John T

[bouncybounder]

I didn't see any flat ribbon cable connectors....I am not sure.

The squeaking sounds was due to a loose part that was rubbing on the fan. I can move the part so that it doesn't make noise. It is supposed to block and control the airflow, I think into the left side of the big fan. When I put it together this time it was hard to see to put it in the right place as the area was cramped. I think the whole thing had been taken apart before and put together wrong which was why it was making noise. No no noise now, anyway and it seems to be blowing fine. 

[Kirk W]

7 hours ago, bouncybounder said:

Also this might not be reliant but when I lite the burners in the rv they pulse rapidly. It is about a ten percent pulse every half second. It is most easy to see when the burners are on high. 

This makes me think that you would be wise to have your LP pressure checked to see if it is varying and causing that pulsing. You may have a pressure regulator problem. 

[oldjohnt]

11 hours ago, bouncybounder said:

The squeaking sounds was due to a loose part that was rubbing on the fan

That's better news then failing fan bushings as it was easily cured. You are doing a good job thanks for the info.

John T