Suburban furnace not turning on, only Dometic AC fan

[ChristianD]

Hi all,

I'm a bit mystified by this issue.  My Ollie has the Suburban/Attwood furnace and when I bought the trailer, the previous owner, I thought turned on the heater.  They ran through most of the trialer operations and were very helpful.  Since I've owned it, I had to get a Truma Aqua Go water heater installed, which I did.  That's about the only thing I've done to it.  I thought the furnace heater worked, but now that I'm trying to get it to turn on, it's only kicking on the Dometic AC fan.  Are they two completely different systems?  I don't see a separate thermostat for the Suburban furnace, so my reading and searching says it works from the Dometic thermostat, but that doesn't seem to work.  I tried holding the Mode button and the Up arrow to reset the thermosat.  When I turned it to furnace after that, the Dometic ac fan didn't turn on, but nothing happened.  Also, I did check and replace the furnace 7.5amp fuse, just to cover that.  Also, I checked that the propane is turned on.

Anyone have any insight.  What am I missing?

 

Edited Monday at 02:06 AM by ChristianD

[Corvus]

My experience is sometimes it can take a while for the propane to get to the furnace. Especially after not being used for a while. Try igniting the stove to make sure the propane has made its way that far then continue on to get the furnace to ignite. There are other potential issues but this is a good starting point.

[ChristianD]

Thanks! That seems to have worked.
I did what you mentioned.  Turned the stove on, then started the furnace from the Dometic thermostat.  It kicked on the Dometic fan, so I thought it wasn't working.  Then I turned it off, but then I heard the furnace was on, so I reset the thermostat again (held power and up arrow at same time) and got the double dashes, which I think means it reset.  Then turned the furnace back on and just it started up without the Dometic fan.  Maybe that's the key and future routine.   Make sure the stove has gas, then after a minute turn the furnace on.  

Next I have to figure out the MaxAir fan issue.  It doesn't like the 13.3v that my solar charges the batteries up to.  From what I've read it shuts the control board off on the fan.  I'll be figuring out how to install the buck voltage converter to steady out the voltage to 12v and keep it consistent.  I'll try that fix for $19 to see if I can get it to work.  Other option is to get a new control board that fixes the high voltage issue but that was 3x the price, or get a Victron Orion-Tr DC-DC 12/12-9, but that too is much more expensive and more complicated.  (I think).

Going on my first overnight on Tuesday, so hope everything goes all right 🙂 

Edited Monday at 04:06 AM by ChristianD

[Ronbrink]

 

11 hours ago, ChristianD said:

I thought the furnace heater worked, but now that I'm trying to get it to turn on, it's only kicking on the Dometic AC fan.

Per the Dometic thermostat manual:  If additional indoor air circulation provided by the air conditioner is NOT desired during Furnace Mode, select “Auto” in Fan Mode to shut the air conditioner fan off. If “Low” or “High” is selected, the air conditioner fan will continue to operate at the selected speed.

Simply, when operating the furnace select ‘Auto’ fan to prevent a/c from blowing.

[ChristianD]

Thanks Ron.  I thought I read through the manual, but obviously it didn't sink in, or I completely missed it. 🙂  

[Corvus]

Great, good to hear you were able to get it going. You shouldn't need to use the stove unless you turn off, or disconnect, the propane tanks for long periods.

What I think happens is when the pressure is off then air is able to diffuse into the system and that has to be purged out. The fastest way to do this is through the stove, or maybe the rear external propane quick connection if installed. Anyhow I'm not a RV propane expert so this could be wrong.

Hope your first night goes smooth.

 

[Ronbrink]

13 hours ago, Corvus said:

You shouldn't need to use the stove unless you turn off, or disconnect, the propane tanks for long periods.

I installed GasStop RV Propane Emergency Shut-Off Valve Gauges on both propane cylinders, which are also useful in testing for minor leaks and purging lines when cylinders are first opened.