Hi bobsue2,
If the furnace is not ON, and temps drop to the mid 20s overnight, the temps inside the coach and in the underbelly could get below freezing and you stand a chance of getting some freeze damage. Even if you leave the furnace ON, if you run out of propane or have a malfunction, it'd be like leaving the furnace OFF.
Faucets, toilet valve, shower, water pump are all areas of concern.
If your refrigerator has an icemaker and/or water dispenser, the water feed line and solenoid are a point of concern. If the frig is in a slideout, the water feed line is exposed to outside air and will be damaged for sure. The solenoid may be heated, but since it's exposed to outside air, it's also a possible point of failure.
The pex water lines will probably survive a dip below freezing, but a hard freeze might cause fittings to expand, leaving you with drips and leaks.
I'd guess you'd have to be below freezing for more than a few hours for the contents of your holding tanks to freeze. But if you're away for a few weeks, who knows.
I'd suggest winterizing.
You might want to review our
user guides on Winterizing and Water Systems Winter Usage.