furnace turning on and off, and no heat.... was working fine...

[scottknight1]

have a 2017 big horn 3160.... when the furnace comes on, it pushes cold air...

the meter shows 4 lit lights with 50amp plug in.... show 1 light on the dash board when not plugged into 110v.... new to RVing... assume the batteries all need to be replaced..... they are 3 hole 6 volt batteries..... do I buy them from camping world? they have interstates for 200 per battery. amazon has trojan batteries for $400 each..... any advice would be appreciated.. the propane tanks I just filled.....so they are not the problem.

 

[Dahillbilly]

I'd remove the batteries make sure they are fully charged & take them to an automotive parts store & have them tested(load). They will be able to tell you if any or all are bad. Another test is using a battery hydrometer after the battery is fully charged uo the meter & compare the readinds in each cell should have 12.50 in a good cell. If any cells have more than .50 difference between high & low reading the battery is going bad. Learned this from a battery manufacturer years ago.

 

[BigFry]

One possibility for the furnace just blowing cold air is that the Sail Switch has failed. This switch, attached to the furnace itself, detects if the fan is blowing air. If it thinks it is not, it will not allow the burners to ignite. The part is inexpensive, and assuming that there is available propane to the furnace this might be a place to start. I believe there are youtube videos on how to replace.

 

[thewanderingeight]

Listen closely when it first comes on, if you can hear a clicking sound coming from the furnace, then it's most likely not getting propane. It will usually try three cycles before shutting off. The clicking is the ignitor trying to start the flame. If there is no clocking noise, then as BigFry mentioned, there is a good chance it's the Sail Switch, which makes the furnace think it's not getting enough airflow. Always a good idea to double-check your vents to make sure something didn't accidentally get placed on top of them restricting airflow.