Motorhomes that have air brakes will usually also have an air dryer. The line running from the air compressor to the air dryer is made from braided steel. Compressed air within in this line creates moisture, making it necessary for you to drain the air tanks on a monthly basis.

Where the air tanks are located will depend on design of the individual motorhome. If the RV has a full air brake system, the front air tank is usually located between the front axles near the floor of the coach, and the rear air tank is positioned just in front of the drive axle up near the floor. The front air tank is divided into two sections - a dry side and a wet side.

The air compressor is mounted to the engine. Air from the compressor travels to an air dryer that has three functions - cooling, filtering and drying the air. Warm humid air from the compressor condenses into water, or water vapor, before entering the air dryer. The air dryer expels moisture at the end of the compressor cycle. At the bottom of the air dryer is a heater that will heat the air when outside temperatures fall below 45 degrees to prevent moisture in the air dryer from freezing.

How often to drain the tanks will depend upon moisture content in the air where you are traveling. As a rule, it is a good idea to drain the air tanks at least once per month. However, if humidity is high, drain the air tank more often. Wear safety goggles while draining the tank, and remember to close the air tank valves once draining is complete.

On earlier model motorhomes, those built prior to 2003, it may be necessary to access the drain cocks on the tanks themselves. Park the motorhome on a level surface and set the parking brake. Chock the wheels and proceed with caution as you go under the vehicle and open the drain valves to evacuate air and water.

Later model motorhomes, those constructed after 2004, provide three valves, two at the front and one at the rear. To drain the tanks, open the valves. It is possible to add this remote fitting to earlier model coaches, which can be purchased through Monaco Coach Corporation National Parts.

The key is to keep the air system as dry as possible. Moisture can build up and form rust particles that can cause corrosion and contaminate the air system airline fittings and orifices in the one way check valves with rust particles. Preventive maintenance of the air tanks requires routine draining.

On top of the air dryer is a spin off filter. Change the filter once every 2-3 years, or more often if you note extensive water coming out of the air tanks.