Furnace runs, then quits, propane full, shore power

The key is the working of the furnace for a period of time. That makes me think that it is going into lockout in which you must break the thermostat call for heat (see excerpt from manual below) or possibly the over temp switch. The furnace may not be actually be getting overtemp, the switch may by weak and breaking at normal operating temp. If the sail switch was bad I would expect the furnace not to heat at all. The propane should not come on until after the sail switch makes. If no intervening act the switch. most likely will not move so furnace will continue to run.

From suburban manual
"All DYNATRAIL direct ignition furnaces must have a flame sensing circuit through the control module that senses the presence of main burner flame. If proper flame sensing is not obtained or if the burner fails to light, the furnace must go into 100% lockout. When lockout occurs, the valve closes and will remain closed until the thermostat circuit is broken. Re-ignition will not occur automatically. If it could, it would not be 100% lockout.
While 100% lockout is a safety factor, it can prove to be frustrating for the RV owner who has experienced lockout problems. Not only can a lockout problem be difficult at times to diagnose, it will result in continuous operation of the furnace blower (that is, until the thermostat circuit is broken) and can drain the battery if the owner is not in the recreational vehicle.

I have the covers off of the furnace on both sides. There is nothing on either side that looks like a fan and sail switch.

But when I pulled the cover off from that is accessible from inside the trailer I smell the low fuel smell. I did have a tank get low this week, but I switched to the full tank as soon as I recognized that odor. I'm not sure why the odor is still lingering till.

Also, I switched the fridge to gas only and it's working fine.

So, how do I find the sail switch? And, are there any other suggestions?

Thank you for the replies. I located a manual online and it describes the sail switch as being on the fan housing. The installation instructions that came with the trailer shows a microswitch in the same spot. That's gotta be it.

When the sun gets up I'll pull the cover off the furnace to see what I can do. I've never had that cover off, so this will be a good exercise.

If not the sail switch or low battery it could be one of those overtemp buttons tripping. Check them with an ohm meter when it happens if you get no reading it is tripping. If near zero it is good.

Almost sounds like a dirty fan sail switch. Locate it and spray all around it with WD-40.

I always run the stove top for a few minutes to bleed off any possible air in the propane lines before using the furnace.

Also a low battery might cause this as well but since you are on shore power I guess eliminates that being the problem. The thermostat runs on DC...

just a couple of thoughts from here...
Roy Ken