Furnace pops breaker after 30 seconds.

[rjsurfer]

My new Cougar has it's first problem, the furnace runs(gets hot)for 30 seconds or so then pops the 15 amp breaker.

It doesn't make a difference if I run on Auto or manual fan, same symptoms.

I'm thinking the fan sounds a little strange, but that could be my lousy old age hearing??

Any ideas....no time to bring it for warranty service we're off on a camping trip Sunday.

Ron W.

[rjsurfer]

OP back, looks like Doug's post is the answer 🙂

Before reading his response, being the genius I am, I changed the fuse to a 20 amp as a test and it worked. Of course, along with the heat came a burning smell so I shut it down immediately.

Makes sense now.

We will be on full hook up this trip so no problem keeping warm.

Ron W.

[Tim_Nowicki]

there ya go! It appears Doug has the answer.

Tim

[dougrainer]

Dometic has a TSB/Recall out for the DF series. There is a possibility that the limit switch wires can contac the exhaust metal tube. IF that happens, I guess the breaker would trip as it would be a short. The solution is 2 fold.
1. You remove the outside exhaust port cover and see if the wires are touching or are melted. If so, Dometic replaces the furnace
2. IF the wires are not touching or damaged, Dometic sends a Fiberglass sleeve to install over the furnace exhaust tube to prevent the wires from touching and getting hot.
I would check this before going any further on repair. Doug

letter

An omission of a plastic wire tie to suspend the heat exchanger limit switch wires up and away from the
exhaust tube vent, allows the limit switch wires to potentially melt on the vent terminal, shorting to
ground, and causing either the fuse or circuit breaker in the circuit to blow, or the sail switch to become
inoperative.

Dometic has determined that certain small and medium Dometic/ Atwood furnaces (AFS, AFM. DFS,
DFM) with serial number range of 73985322-81099541

[rjsurfer]

time2roll wrote:
Bring an electric space heater if you will have utility power.

No problem, I'm bringing my Mr Buddy Heater along with my Vornado electric.

Ron W.

[time2roll]

Bring an electric space heater if you will have utility power.

[rjsurfer]

Ok, some more details.....

It's a Dometic DF series furnace controlled by the new InCommand system that Keystone is now installing.

The breaker that is tripping is a 12 volt 15 Amp breaker on the 12 volt side of the distribution panel. After 30 seconds it trips and the associated red Led light pops on. I can reset it by turning off the furnace control.

It doesn't matter if I run it Auto mode or Manual mode. Of course selecting manual mode for fan spèed also turns on the AC fan in the ceiling.

The manual does go into detail about some led error code faults but I'm not pulling the furnace out to read them.?...I'll leave that to the warrantee people at the dealer when we get back from our camping trip.

Ron W

[Chris_Bryant]

If it’s the Atwood/Hydroflame 8500 series, either the breaker is bad or the blower motor is going. You can unplug the breaker and plug a 15 amp fuse in place. If it’s a bad breaker, that will work and be safe.

[Old-Biscuit]

Clear up some confusion......

POST BRAND/MODEL of your Furnace

Most are ALL DC
Some are AC

Fan...
Auto/Manual....suggest you are doing that at the Wall Thermostat for A/C and Furnace (Cool/Heat)
Fan settings on thermostat control the Fan for A/C Unit only.
In AUTO the Fan runs when A/C Unit Runs
In Manual the A/C fan will run when furnace is runs....

All furnace controls/functions are via furnace circuit board when Thermostat Contacts Close (in Heat Mode)


SO Brand/Model AND which 15A breaker is tripping????????????

[Harvard]

If it is a 120VAC breaker then it may be due to the increased load from the converter. The converter converts 120VAC to 12 VDC. 12VDC then powers the furnace.

Maybe the 120VAC 15 Amp breaker supplies power to something else along with the converter.

[time2roll]

120v breaker or 12v fuse?

[BFL13]

What do you mean by a "15 amp breaker"? Where is it located at the furnace or elsewhere? Usually "breaker" means 120v, so it is confusing. There are DC breakers though--resetting and those with buttons to reset them.

[rjsurfer]

MEXICOWANDERER wrote:
Mr Ron,

Without hinting about volts and amps, you are opening the floodgate for 500 different opinions with a correct answer hiding like a needle in a haystack.

Polite suggestion. It's new, right? Take it back to the dealer. Return home and pop a brewski. 🙂

I will be taking it to the dealer but we're heading off for 10 days near Asheville first, no time for dealer trip.

Ron W.

[Lynnmor]

First of many suggestions:

If the fan sounds strange, maybe it has interference or a dry/
tight bearing causing it to pull more amps.

[MEXICOWANDERER]

Mr Ron,

Without hinting about volts and amps, you are opening the floodgate for 500 different opinions with a correct answer hiding like a needle in a haystack.

Polite suggestion. It's new, right? Take it back to the dealer. Return home and pop a brewski. 🙂