Help replacement furnace problem

Does the blower start at all? If it doesn't, the sail switch is stuck closed.

This a front output non-ducted rear direct exhust vent. Nothing obstructing it. So the question I guess becomes, is there anything securing the blower fan from the factory I had to remove that i did not? Or what is the minumum voltage necessary to run the blower?

Check for restriction in air return AND air vents/ducts.

Check voltage at the furnace. As indicated 12.0 is WAY discharged. As a test, put a battery charger on so that voltage is above 12.5 and see if that changes things.

If it does, check voltage at the battery and again at the furnace with the fan running. If more than a .2 VDC drop in the wiring, up-size wiring, clean connections, etc.

Do NOT start by assuming furnace internal problem. The SAIL SWITCH HAS TO CLOSE FOR THE FURNACE TO TURN ON THE PROPANE AND IGNITOR. Insufficient air flow for any/a combination of reasons will keep this from happening.

Before replacing the furnace, I would have trouble-shot the air-flow problem.

Along with airflow into and out of the heating side, did you check for obstructions in the ducting inside the RV? Most likely cause is a mouse nest built inside of one of the heating ducts.

So far in different RVs I have found a mouse nest in the cage-fan, and in one of the ducts. The one in the duct included the nest and dead mouse. Evidently she died from the heat before the furnace shut down from low air-flow as designed.

It is kinda shocking to learn that 12.0VDC is approximately 50% state of charge on our deep cycle batteries.

Here is a chart showing the various Dc VOLTAGE verses the battery state of charge numbers.

Moved from Forum Technical Support

Newer battery & brand new power center.....Voltage close to 12V...little less with lights on


Your battery voltage is very low........at 12V that is only 50% charged.
Need to check you charger output

Low battery voltage will cause furnace blower fan to run slower....less air flow

And you need to be sure return air/discharge air/exhaust ducts are clear...no filters in return, no loose material, nothing up against grills etc.