RV Interior Cleaning and Moisture Control Before Winter Storage

I've opened an RV in spring that smelled like mildew and found mouse evidence in three different compartments. I've also opened one that was exactly as I left it in October. The difference wasn't the climate, the storage facility, or luck — it was how thoroughly the interior was cleared and sealed before storage.

The food-and-rodent problem is underestimated

Mice can squeeze through a gap the diameter of a pencil. An RV has dozens of these gaps — wire penetrations, hose fittings, the seam around the fresh water tank access, vent openings in the underbelly. Before thinking about moisture control or chemical management, walk the exterior perimeter and stuff any gap you find with copper mesh or steel wool. Follow with expanding foam sealant where appropriate — rats chew through foam, but mice won't bother if the mesh makes the gap inaccessible.

Inside, remove everything that has any food value: obvious food, but also condiments, sealed canned goods with cardboard labels, pet food, anything in cardboard packaging. Mice don't just eat food — they shred cardboard and fabric for nesting. An empty cabinet without food scent is less attractive than a cabinet with even an empty cracker box. A RV moisture absorber placed in each cabinet and bedroom area handles the second problem: the residual humidity from cooking, showering, and breathing that condenses on surfaces during cold storage.

The refrigerator and appliance sequence

The refrigerator gets its own protocol. Empty it completely, wipe down the interior with a baking soda solution, leave the door propped open approximately one inch — this allows air circulation and prevents the permanent mildew smell that develops in sealed, unventilated fridge compartments. Some RV owners tape a small activated charcoal pack inside to absorb any residual odors. Prop it with a folded piece of cardboard so the magnetic seal doesn't close completely.

The air conditioner shroud should be cleaned and covered with a breathable RV AC cover to prevent debris and wasp nest accumulation over winter. Don't use a non-breathable plastic cover — it traps moisture against the unit.

Plumbing basics if you haven't done them

The plumbing sequence is: drain fresh water tank, drain water heater (bypass it with the bypass kit first), run each faucet to empty the lines, then pump RV antifreeze through the system via a pump conversion kit until pink solution comes from every faucet and showerhead. Pour four ounces of antifreeze down each drain to treat the P-traps. Don't use automotive antifreeze — it's toxic. RV-specific antifreeze is food-safe and drain-safe.

What I'd skip

Skip the professional winterization service for a standard Class B or Class C RV if you've done it once before. The plumbing sequence is the same every year. The first year with a new RV layout, a professional walk-through that you follow along with is worth the cost — you learn the locations of every valve and bypass. After that, it's a one-person job that takes about ninety minutes.

Also skip leaving the battery connected through storage if you're not maintaining it with a float charger. A disconnected battery in cold storage discharges slowly over months but doesn't sulfate as quickly as one that's drawn down by the RV's parasitic loads (clocks, LP detectors, inverter standby). Disconnect, bring inside, and maintain on a battery tender through the winter. The battery will be at full capacity when you reconnect in spring.