"Cooling fan" on furnace continually...

[msubobcats]

We just returned from picking up our 5th Wheel at the dealership after having a couple very minor issues repaired.
Patti had taken our neighbor in to show her the new unit and she noticed the fan running. I said let's just let it run for a bit to see if it has to cycle through a cooling sequence... NOPE. This fan is in/at the breaker panel. It looks as if it is an all in one unit. And I am guessing it is the fan that runs with the furnace to cool the furnace after it shuts down. Anyone else had an issue. We do have an appointment to take it BACK to the dealer on the 25th but if I can somehow not have to go BACK again it would sure be nice.
I have just shut off the 15A breaker that operates the fan....
Thank you

[nellie1289]

pretty sure you problem is you have the fan set to run "on". need to change it to the "auto" setting so it comes on and off with the a/c unit. I think you just hit the button a couple times to cycle through.

[JRTJH]

I think you may be confusing two fans... First, the furnace fan is 12VDC and is not controlled by a 15 amp circuit breaker (on the AC panel), but by a replaceable fuse (probably 15 amps) on the DC panel.

I'm "speculating" here, that one of two things may have occurred. First, your DW may have walked into the trailer just as the furnace was "shutting down" from a failed attempt to ignite. During the ignition cycle, the fan starts, after a "purge period", the ignitor attempts to light the flame. If the controller doesn't "sense a flame" it will make two more attempts at ignition. If, after three unsuccessful attempts, the fan will run (without heat) for another "purge period" to clear any remaining propane from the firebox. Then the furnace will remain "dormant" until the thermostat calls for heat and the sequence will recur.

The second possibility (and my guess) is that while the RV was at the dealership, the batteries were nearly "drained" and what you're hearing is the fan on the converter/charger. It's a small "computer fan" that cools the transformer in the converter. It is louder in some than in others, and is controlled by the 15 amp Circuit Breaker on the AC panel in the power distribution box. My guess is that if the fan you're hearing turns on/off with a circuit breaker (probably marked "CONV") then the fan you're hearing is the power supply/converter fan. It is normal for that fan to run when the converter output is above a "set level" (probably around 10 amps DC power. Turning on a couple of lights and having a "nearly dead battery" would be enough power demand to start the fan.

I'd suggest you check again later on to see if the fan is actually the furnace or if it's the converter. You can check by turning the thermostat to "heat" and dialing up the temperature until the furnace starts.

I'd guess by doing that, you'll hear an entirely different "fan noise".... Hope so, anyway :)

[Bob Landry]

The furnace fan does not have speed settings on the switch, it is either on or off and if there is no ignition, the fan runs for a short time and then shuts off. I think he is hearing the fan in the converter. it will turn on with varying loads such as overhead lights.

[msubobcats]

Just came back inside after checking the "fan running. It is a fan behind/under the breaker. It is running. And it goes off when I turn off the 15A breaker but maybe that breaker may have a function over the 15A fuses???
So now I know how to tell the difference of locations. The furnace is next door under the fridge.....
Now to figure out why it is running...
I did notice when I was running my landing gear up to bring the 5th Wheel home from the dealership that my battery was at 11.6V so it was drained down a bit. Noticing that I plugged into the truck to finish hooking up...

[JRTJH]

Please reread my post. The fan you're hearing is, as Bob Landry agrees, is the converter fan. The reason it turns off when you turn off the AC Circuit Breaker is because that fan is a part of the "Converter" which is powered by AC. ie: Turn the circuit breaker off will turn the converter power (and its fan) off.

If you want to hear the furnace fan, turn on your thermostat to "heat" and dial up the temperature until the furnace activates. You'll hear the furnace fan come on. It is an entirely different sound, not the same as the converter fan.

Bottom line, the converter fan operation is "normal" and you will hear it any time your converter DC output is above a specific level. You're at (or above) that level with a battery at 11.9 VDC and one or two 12 volt lights burning.

[msubobcats]

Please reread my post. The fan you're hearing is, as Bob Landry agrees, is the converter fan. The reason it turns off when you turn off the AC Circuit Breaker is because that fan is a part of the "Converter" which is powered by AC. ie: Turn the circuit breaker off will turn the converter power (and its fan) off.

If you want to hear the furnace fan, turn on your thermostat to "heat" and dial up the temperature until the furnace activates. You'll hear the furnace fan come on. It is an entirely different sound, not the same as the converter fan.

Bottom line, the converter fan operation is "normal" and you will hear it any time your converter DC output is above a specific level. You're at (or above) that level with a battery at 11.9 VDC and one or two 12 volt lights burning.

To update: I went out to the fifth wheel yesterday and remembered the fan issue. I turned on the breaker that feeds the fan and, voila, it was no longer "fanning". So it is a normal operation when the battery has drained below the acceptable voltage limit.
THANKS to all for your input.

PS: that means we can cancel our appointment with the dealership.

[sourdough]

You probably already have them, but it you don't, replace all your lights with LEDs. It will make a huge difference in now often you hear that converter fan.