Suburban Furnace...

[retiredtech]

Furnace will not relight when temp falls,installed new T-Stat,must move t-Stat to off then on to get heat then shuts off at temp and won't restart when temp falls/

[mikf]

does it try to do anything at all when the temp falls? do you have to wait or will it fire up right away after it fails?

[jbilling]

Are you sure it is getting up to the desired temp and shutting down? Or is it getting warm but furnace is actually shutting down before it reaches temp set by thermostat. It almost sounds like there is a safety being triggered in the furnace or you lose flame(another safety) and it shuts down. It won't relight until you shut power off which is resetting the system.

Jon

[RV Wizard]

Start with pulling furnace and cleaning the burner, heat exchanger, orifice, igniter and making sure the point gap of 3/16' is correct. A bench test should be performed to check ignition and proper operation while the furnace is out. once everything is good, re-install.

[farmallbob]

Mine did this one time several years ago. Was not getting proper power. Found a loose wire at the battery post. Sometimes it is the simple things.

[SUMDALUS]

retiredtech,

Subruban made two different models of furnaces, the NT (the box is square) and the SF (the box is rectangular).

If you have an older NT model, the most significant cause of failed restart was caused by an overheated igniter board. The best fix I found for this problem was a Dinosaur Electronics Extend-a-Life kit. This kit allows the igniter board to be moved away from the furnace box (normally it is right next to the heat exchanger). The kit adds a connector board and 24 inch long wires enabling you to remount the igniter board well away from the heat. Note: This kit will not work with a fan control igniter board!

There are several for sale on ebay.

Hope this helps

Dale Lee Sumner
RVIA Master Certified RV Service Technician
Mobile RV Medic

[retiredtech]

Originally Posted by mikf

does it try to do anything at all when the temp falls? do you have to wait or will it fire up right away after it fails?

Must open and then close T-Stat to relight.

[retiredtech]

Originally Posted by jbilling

Are you sure it is getting up to the desired temp and shutting down? Or is it getting warm but furnace is actually shutting down before it reaches temp set by thermostat. It almost sounds like there is a safety being triggered in the furnace or you lose flame(another safety) and it shuts down. It won't relight until you shut power off which is resetting the system.

Jon

This may be the case,seems like it is not getting up to set temp. Board,Limit switch and four pin connector have been replaced.

[cmpman]

Hello all, I am new to rving we just bought a 35' class a motorhome . The only problem I have so far is the furnace. It heats fine but when I shut the thermostat off (to shut heat off) I have come back to find the blower still running. I have to pull fuse to stop it any ideas thanks.

["007"]

cmpman welcome to irv2.
In this answer giving to you it was asked are you allowing the furnace to cool down after heating the coach or is the fan after the cool down, still continues to run.
Its best for you to stick with your own question and not jump on someone else's question even if you may think its your same problem.
If the fan keeps running it could be a failed sail switch or over heat switch but you need to answer your original post so we can help you.

[mikf]

Originally Posted by cmpman

Hello all, I am new to rving we just bought a 35' class a motorhome . The only problem I have so far is the furnace. It heats fine but when I shut the thermostat off (to shut heat off) I have come back to find the blower still running. I have to pull fuse to stop it any ideas thanks.

cmpman, this may sound crazy, but turn off your flouresent lights and see it solves the problem. you could have a bad ballast. it happened to me.

[retiredtech]

up date... called suburban and talked with tech/engineer,Told me to replace Blower motor,running to slow not moving hot air out of box,did that another 100 bucks,now up to $700. guess what,same problem %#&*$%#$

[mikf]

Originally Posted by retiredtech

Furnace will not relight when temp falls,installed new T-Stat,must move t-Stat to off then on to get heat then shuts off at temp and won't restart when temp falls/

are you saying the flame shuts off and the blower keeps running and the flame will not reignite? or everything shuts down and will not come on again when the temp. drops? if just the flame shuts off and will not come back on then I can see how the motor could be the problem, but before I bought one I would check your voltage to make sure it is in the range and check for any blockage in the ducts that would restrict the air getting out of the furnace.

[retiredtech]

Furnace shuts down,board apparently goes into Lock-Out,will re-lite only after opening and closing T-stat!