Furnace Trouble

[steveL332]

Once I hit "restore" on my battery disconnect the furnace fan immediately turns on then one second later turns off... One second later on, then one second later off... Cycling repeatedly until I switch to disconnect. The thermostat is off. The only way to stop it is to switch to disconnect or open up the outside furnace panel and turn the switch to off. Any idea what could be causing this?

[ddlonewolf50]

Originally Posted by steveL332

Once I hit "restore" on my battery disconnect the furnace fan immediately turns on then one second later turns off... One second later on, then one second later off... Cycling repeatedly until I switch to disconnect. The thermostat is off. The only way to stop it is to switch to disconnect or open up the outside furnace panel and turn the switch to off. Any idea what could be causing this?

Hi there Steve , we need the year , make and model of the MH and info for the furnace name plate . Keep your chin up [emoji6] someone may have some info for you .

[javelin]

Welcome to the forum. That is a new one that I have not heard of before......but since you don’t say much about your coach or the furnace model number, then generically speaking the furnace control board normally turns on the blower motor when there is a call for heat from the thermostat. So if you turn down your thermostat (no call for heat) does the blower motor stop cycling within 30 seconds and stay off? What about turning "off" the thermostat? If the blower motor continues to cycle on/off every second or two then the control board would be highly suspect to me, because one second is not really enough time for the blower to even get up to full speed to activate the sail switch IMO.

[steveL332]

Yeah, I guess I should have given more info. Lol.
It's a 2017 Thor Chateau 31W. It's an Atwood furnace. I don't have the RV or the manuals with me. The thermostat is completely turned off, but it still cycled repeatedly.

[javelin]

OK....so have you opened up the furnace outside and inspected all the wiring for any obvious signs of melted, shorted or broken/disconnected wires etc ? I would also expect that turning the furnace on/off switch (in the furnace) would stop the blower cycling......I will really be surprised if it still cycles then.



Any repair history you can provide on the furnace operation/repair? "Was working fine last week and then this happened" etc. New thermostat recently; new parts in the furnace recently......anything that might help us help you. At this point I am still thinking bad control board.... when the thermostat is not calling for heat the control board should not be turning on the blower at all. You could try disconnecting a thermostat wire at the furnace end and make sure it is not a bad thermostat doing a dance with the furnace control board.

[steveL332]

I did turn off the switch inside the furnace to get it to stop cycling. All the wires were connected.

[javelin]

Well at least cutting the 12vdc at the furnace works (as well as your coach use/store switch). If there are no obvious wiring issues and no recent re-wire jobs or work done on the furnace or thermostat.....the only thing I can suggest is a control board change on this one. Perhaps someone else on the forum has seen this trouble before and can respond with their findings.

[RichS]

I just brought my RV back after the hurricane. Turned on battery furnace blower starts. Turn battery off blower stops hook up to shore power without battery on blower starts. I wonder if water got on control board.

Any ideas anyone.

[taylorbob1]

Could be something as simple as the wall thermostat

It thinks that you want the Thermo in the “Heat” position with fan in the “on” position

Obviously, you have the fan in the “auto” position and the heat/cool in the “off” position

You could try to disconnect the Thermostat from wall.

[RichS]

It just started today. Never used the furnace. Never touched anything. I m thinking control board. Maybe hurricane blew some water on the control board. I have vents on my furnace access panel.

[RichS]

It finally stopped by itself. Maybe control board is drying out.

[kwplot34]

2016 31L, mine would do the same thing, water gets on the control board. After taking the cover off and removing the control board to dry all was fine until it got wet again. I finally removed the board and purchased a 2 part encapsulating compound and encapsulated the board, that was 2 years ago and no more problems.

[RichS]

I am probably going to sound stupid but what is the name of that compound that you are using on the board.

Thanks

[apr67]

My Attwood on a 2017 Hurricane has done the same thing several times. Including in the desert when I am sure no moisture was involved. Recently it did a new trick and the fan for the furnace just turned on and stayed on. Removing power (unplugging from AC and disconnecting) the battery usually fixes it, but not this time. So I pulled the cover and hit the switch on the furnace and figured I would look at it later. Well doing that caused my AC to also not work.

Not sure what is going on, but I decided I would try upgrading to a digital thermostat and see if the problem goes away.

[16ACE27]

Originally Posted by apr67

My Attwood on a 2017 Hurricane has done the same thing several times. Including in the desert when I am sure no moisture was involved. Recently it did a new trick and the fan for the furnace just turned on and stayed on. Removing power (unplugging from AC and disconnecting) the battery usually fixes it, but not this time. So I pulled the cover and hit the switch on the furnace and figured I would look at it later. Well doing that caused my AC to also not work.

Not sure what is going on, but I decided I would try upgrading to a digital thermostat and see if the problem goes away.

The furnace supplies power to the thermostat so turning off the furnace also turns off the air conditioning.

[kwplot34]

Originally Posted by RichS

I am probably going to sound stupid but what is the name of that compound that you are using on the board.

Thanks

MG Chemicals translucent epoxy, Encapsulating and Potting compound.
Part# 832C-375ML

[RichS]

Thanks for the information