Now is the best time to prepare your motorhome’s roof air conditioner for the summer ahead.
By Brett Wolfe, F252125
April 2011
Make sure your motorhome’s rooftop air-conditioning system is ready to pump out cool, refreshing air when the weather heats up by performing the following maintenance steps.
- The air return filter(s) need to be cleaned and/or replaced frequently. Shine a flashlight up into the air return to determine whether dirt has accumulated on the filter(s). The filter area is small, so it is not unusual that you would need to clean the filter(s) on a weekly basis during times of heavy air conditioner use.
- If your air conditioner utilizes a ducted system, check for an airtight connection where the ductwork attaches to the air conditioner’s output, plus all other connections throughout the ducting system, including the air return.
- Do not overtighten the rooftop unit to the inside unit. Just snug the four bolts holding the two parts together. The bolts are accessible by removing the inside cover. Try to compress the foam roof gasket as little as possible. If water leaks in from the roof, try tightening just a little more. If it still leaks, replace the rooftop air conditioner gasket (available at most RV stores).
- Other items, such as the condenser, the evaporator, the fan motor, and capacitors must be serviced from the roof. To inspect and work on these, turn off the air conditioner’s 120-volt-AC power at the breaker box or just unplug the motorhome from shore power. Determine whether it is safe to climb on the roof. (This may be best left to a professional service technician.) In particular, do not go up in windy, wet, or stormy weather, and make sure to wear the proper clothing and shoes. Remove the air conditioner shroud to service these items.
There are two sets of coils on the roof. The one you will see when you first remove the shroud is the condenser and can be cleaned easily with water or compressed air. Be sure that you do not get water into the electrical area.
The other coil, the evaporator, is located inside the evaporator housing. If you ever get that moldy, cave-like smell in the motorhome when first starting the air conditioner, this is where that smell is coming from, and it needs to be cleaned. This is likely a once-a-year job when the motorhome is stationed in a humid area where the air conditioner is used frequently and the evaporator stays wet much of the time. Use a professional evaporator cleaner, available at any HVAC store, and an old toothbrush.
While you are on the roof (with the power still off), check all electrical connections. Also, inspect the electrical capacitors to make sure they are not deformed or leaking. Do not touch the terminals on the capacitors, as they do retain a charge even with the power off.
- Some fan motors have oil ports on each end of the motor; others have sealed bearings. If your air conditioner has a fan with oil ports, add three (and not more) drops of light machine oil or sewing machine oil to each port. Also, ensure that the fan motor is tight on its mounts. Finally, check and remove any mud dauber nests or other debris that can throw the fan off balance or short out the electrical connections.
Follow these simple preventive maintenance steps and you should enjoy the cooling capabilities of your rooftop air conditioner through the sweltering days of summer.