If you have a washer/dryer in your MH, you CANNOT use compressed air to "winterize' it, you must pump RV anti-freeze through it per mfgrs instructions. The Aqua-hot system should be tested for freeze point.
After that, I follow these instructions from RV University:
If you have any inline water filters remove and bypass before starting.
Drain the fresh water holding tank.
Drain and flush the gray and black holding tanks. Clean the black tank with a wand. Lubricate the termination valves.
Drain the water heater. Open the pressure relief valve and remove the drain plug. CAUTION (never drain the water heater when it is hot or under pressure).
Open all hot and cold faucets; don't forget the toilet valve and outside shower.
Locate and open low point drain lines. Using the water pump will help force water out, but turn it off as soon as the system is drained.
Recap all drains and close all faucets.
By-pass the water heater. If you do not have a by-pass kit installed the water heater will fill up with antifreeze before it goes through the water lines, wasting six gallons of antifreeze.
Install a water pump converter kit, or disconnect the inlet side of the pump (the line coming from the fresh water holding tank) and connect tubing from the pump into a gallon of RV antifreeze.
Turn the water pump on and pressurize the system. Starting with the closest faucet slowly open the hot and then cold valves until antifreeze appears. Replace antifreeze jug as required.
Repeat on all faucets from the closest to farthest away. Don't forget the outside shower.
Flush the toilet until antifreeze appears.
Turn the water pump off and open a faucet to release the pressure. Go to the city water inlet. Remove the small screen over the inlet and push in on the valve with a small screwdriver until you see antifreeze. Replace the screen.
Pour a cupful of antifreeze down each drain. Pour a couple of cups in the toilet and flush into the holding tank.
If your water heater has an electric heating element turn it off. This will protect the element if the unit is plugged in while being stored.
Make sure all faucets are closed.
Consult your owner manuals for winterizing icemakers and washing machines.
The unit is winterized.