2014 3170ds furnace removal

[Donovon]

Hello,
This is my first post on this forum, and I hope you can help! We have a 2014 Forest River Sunseeker 3170ds.
It was chilly this morning so we tried to turn on the furnace. We hear a single click from under the refrigerator and then nothing. Fuses are good, breakers are good, 13.62 volts at the battery. I'm guessing it might be the sail switch. I'm trying to remove the furnace to check the switch, but it seems to be stuck at this point. Screws are out, duct work is disconnected and free. Does anyone have a video or manual that could walk me through the process? Thank you.
-Donovon

[dsherman26]

Did the fan start? No fan, no go. Yes, it is the sail switch, but the sail switch is doing its job if the fan didn't start. The exhaust is probably a friction fit, you might have to wiggle it and pull to get it loose.

[Donovon]

Thank you for your reply. Do I need to replace the sail switch, or can it be serviced?

[dsherman26]

Originally Posted by Donovon

Thank you for your reply. Do I need to replace the sail switch, or can it be serviced?

Again, did the fan start? Replacing the sail switch won't fix anything if the fan isn't running.

[Donovon]

Sorry, I misunderstood. The fan did not start.

[Capacitor]

It’s not the sail switch then.
What model furnace.

[Donovon]

I'm not sure. Still working on getting it out.

[5picker]

Everyone seems to jump to the conclusion that all furnace issues are sail switch related.
They are not.

If your furnace clicked but no fan, it is not the sail switch.
Provide the make/model and we can point you to the manufacturers manual that almost always have troubleshooting steps.

[Capacitor]

On most furnaces, the plenum stays and the guts pull out. There is one screw holding it in, possibly in the center black bracket middle of picture. Remove the exhaust and combustion air intake vent on the outside as it is a tight fit.

[Larry-NC]

Originally Posted by Donovon

Hello,
This is my first post on this forum, and I hope you can help! We have a 2014 Forest River Sunseeker 3170ds.
It was chilly this morning so we tried to turn on the furnace. We hear a single click from under the refrigerator and then nothing. Fuses are good, breakers are good, 13.62 volts at the battery. I'm guessing it might be the sail switch. I'm trying to remove the furnace to check the switch, but it seems to be stuck at this point. Screws are out, duct work is disconnected and free. Does anyone have a video or manual that could walk me through the process? Thank you.
-Donovon

Donovon, you're doing it wrong. You never remove the outside case (plenum) or disconnect the ductwork. (From the picture that is a Suburban SF-series furnace.

What you do (most is already done) is:

1. Disconnect gas line. (probably already done)
2. Take off front cover (already done)
3. Remove the furnace fuse
4. If there are external connectors, disconnect the 4-wire bunch
5. Remove anchor screw at the bottom center (where those two braces meet at bottom center)
6. Grab the firebox and wiggle it as you pull until it begins to come out.
7. As you pull it out, feed the four wires into the housing.
8. When it comes out, the circuit board, blowers, and sail switch will come with it.

This is a lot of work to do for a wild guess. Before you go further, answer these questions:

• Did the fan run at all? (No power or sail switch shorted--this is rare)
• Did the fan start to run 15 seconds and the just stop? Three times? (This is indicative of a sail switch problem.)
• Were you able to hear the fan run, and after 15 seconds, hear the gas valve open (Clunk) and the ignition begin (click-click-click)?
• Did you/someone go outside by the vents and smell unburned propane? Ignition problem, sail switch is fine.

If you do pull it out, some people do this to make dealing with cable easier:

• Buy a 4-wire trailer extension cable like this from Amazon or elsewhere
• Stretch it out, fold in half, and cut it. Now you have a plug and socket
• In the four wires connected to the furnace, find Ground (Probably white). Cut that wire. In the cable leading TO the furnace from the battery and thermostat, use the plug that has one bare contact, and connect the white cable to the bare contact. Connect the one enclosed contact of the other plug. Now press the two plugs together and, one-at-a-time cut a cable wire and connect the two parts to the same pin on each of the respective plugs. You should end up with the cable coming FROM the furnace having three bare contacts and one insulated, and the cable from the battery and thermostat having three insulated contacts and one bare one.

[jimmoore13]

I'll echo others.
1) You did not report disconnecting the propane line from the furnace. That would prevent removal.
2) Go outside and remove the screws holding the exhaust/combustion air intake housing (manifold) from the side of the rig. Be careful with the goop that forms the gasket between the exhaust and the camper body...it can be reused. By removing the exhaust from the outside, it releases the friction fit between the exhaust pipe on the furnace and the exhaust/intake "manifold" on the outside. And, when it comes to re-install the furnace, get the furnace in place first, then, from the outside of the rig, fit the exhaust manifold on the exhaust pipe for the furnace...MUCH EASIER.
3) I concur with others that, since you report NO FAN at all, it's not the sail switch. If the fan does not start, it can't create the air pressure needed to close the sail switch. The fan will always start and run for a few (15 to 30) seconds while the brains of the furnace wait for air pressure generated by the fan to close the sail switch and confirm that the fan is running. If the fan is not running, the furnace will refuse to fire, because the blower fan will not move the heat out of the heat exchanger, and the furnace would very quickly overheat and suffer damage...and, perhaps, start a fire.

Possible problems likely (not for certain) boil down to a bad connection to the fan motor, bad fan motor, or fried circuit board controlling the furnace. A much longer shot would be that a sensor that detects propane pressure in the line might be stuck and refusing to start the furnace...if there IS such a sensor. This doesn't make much sense, however, because most furnaces will attempt to start even if there is no propane tank on the tongue of the camper.
The fact that you hear a "click" when you call for heat suggests that the circuit board is asking the fan to run, but it won't start. That kinda points to the blower fan.

IF YOU CAN, prior to pulling things apart too much more, my hunch would be to try to spin the blower fan by hand. Does it spin easily? If so, it MIGHT be OK. If not, the bearings might be dried out or the motor fried from being stuck. Next, double check the wire powering the fan...see if it's solidly connected to the fan (more than likely hard wired to the motor) and solidly connected to the control circuit board...perhaps a removable connector. If you can get to the wiring for the blower fan, you might test the blower by running a 12 volt cheater wire from your battery's positive terminal in to the furnace and see if you can make the fan run all by itself. If the blower fan has two wires, one is positive and one is negative. The negative wire might be screwed to the cabinet for chassis ground...or the control board may carry the circuit to ground. If it's just one wire, that's positive, and you'll need to make sure the ground wire is attached to the furnace cabinet to make it run or run a pair of wires from the battery...one plus and one minus (ground).

A thought on the possible why. Mice wreak havoc in campers and cars. They love to chew the insulation on wires...the insulation is actually a "food-grade" material. If you see mouse droppings anywhere in your rig (it's used and older), the mice/rats could have chewed more than just your fan wire. This, of course, is a very wild guess, but rodents and campers don't mix well, and a chewed wire would not be a surprise. ALSO NOTE: if this suspicion is confirmed, you need to clean and sanitize (rag with a bit of clorox solution on it) your furnace...and check the ducts. Rodent droppings and urine can be very hazardous to your health. Educate yourself on cleaning up after a rodent infestation.

I don't propose any of this as "THE" solution. Just options to expore...and thoughts on removing the furnace. I've had mine in and out several times, and it was actually very easy once I disconnected the propane and removed the exhause manifold.

Best of luck.

[Larry-NC]

Originally Posted by jimmoore13

I'll echo others.
2) Go outside and remove the screws holding the exhaust/combustion air intake housing (manifold) from the side of the rig. Be careful with the goop that forms the gasket between the exhaust and the camper body...it can be reused. By removing the exhaust from the outside, it releases the friction fit between the exhaust pipe on the furnace and the exhaust/intake "manifold" on the outside. And, when it comes to re-install the furnace, get the furnace in place first, then, from the outside of the rig, fit the exhaust manifold on the exhaust pipe for the furnace...MUCH EASIER.

I've had to do this once. There's an asbestos gasket that tears--you have to be careful, or maybe order another one.

Others have reported being able to slip the furnace assembly out and back in. If I were doing this again, I'd do it the same way:

• Pull it out.
• Do the work.
• Try to put it back. If it doesn't fit in 10 minutes, take the outside vent off.

Originally Posted by jimmoore13

3) I concur with others that, since you report NO FAN at all, it's not the sail switch. If the fan does not start, it can't create the air pressure needed to close the sail switch. The fan will always start and run for a few (15 to 30) seconds while the brains of the furnace wait for air pressure generated by the fan to close the sail switch and confirm that the fan is running. If the fan is not running, the furnace will refuse to fire, because the blower fan will not move the heat out of the heat exchanger, and the furnace would very quickly overheat and suffer damage...and, perhaps, start a fire.

Possible problems likely (not for certain) boil down to a bad connection to the fan motor, bad fan motor, or fried circuit board controlling the furnace. A much longer shot would be that a sensor that detects propane pressure in the line might be stuck and refusing to start the furnace...if there IS such a sensor. This doesn't make much sense, however, because most furnaces will attempt to start even if there is no propane tank on the tongue of the camper.

There is no propane-pressure sensor. The three sensors are:

• The sail switch
• The ignition (flame) sensor
• The overtemp-limit switch at the top of the front cover

Thinking about it, the overtemp-limit switch stops the propane flow but keeps the fans running (to cool the unit off), so it's not that.

Originally Posted by jimmoore13

If the fan is not running, the furnace will refuse to fire, because the blower fan will not move the heat out of the heat exchanger, and the furnace would very quickly overheat and suffer damage...and, perhaps, start a fire.

Actually, if the fan were not running and somehow an attempt was made to ignite (propane + spark), ignition would not take place because the gas-air mix is wrong, and the control board would shut off propane, attempt to purge the chamber and retry two more times and go into lockout. Of course, the sail switch sensor prevents this sequence.

Originally Posted by jimmoore13

IF YOU CAN, prior to pulling things apart too much more, my hunch would be to try to spin the blower fan by hand. Does it spin easily? If so, it MIGHT be OK. If not, the bearings might be dried out or the motor fried from being stuck. Next, double check the wire powering the fan...see if it's solidly connected to the fan (more than likely hard wired to the motor) and solidly connected to the control circuit board...perhaps a removable connector. If you can get to the wiring for the blower fan, you might test the blower by running a 12 volt cheater wire from your battery's positive terminal in to the furnace and see if you can make the fan run all by itself. If the blower fan has two wires, one is positive and one is negative. The negative wire might be screwed to the cabinet for chassis ground...or the control board may carry the circuit to ground. If it's just one wire, that's positive, and you'll need to make sure the ground wire is attached to the furnace cabinet to make it run or run a pair of wires from the battery...one plus and one minus (ground).

I vaguely recall that there was a short period when Suburban tried plastic squirrel cage wheels--and that they could break. I could be wrong on this. Something easy to check for.

[jimmoore13]

Thanks, Larry, for the excellent amendments of my comments. Very helpful.