Air Conditioner Maintenance Part 2: Up on the Roof

In our last installment we discussed how to handle the "inside the rig" part of air conditioner maintenance. Now we move to the part of the job will take you up topside. You’ll need a sturdy ladder. As a general rule to protect your roof, don’t walk on it. This particularly applies to older rigs that don’t have a solid plywood deck under the roofing material. Best to put a "kneeler board" across the rafters and knee walk across it to reach the ac unit.

At the unit, check out the condition of the condenser fins. These little guys provide a broad surface for outside air to draw away the heat pumped out from the inside of your rig. If they’re bent, like the two photos show, they’ll need to be straightened out to remove that heat efficiently. A thin knife or screwdriver blade may help. Or you can use an air conditioner fin comb--a specialty tool that can help if the fins are not too badly bent. We once spent countless hours with a knife blade straightening out a whole mess of fins that had been completely bent over.

While on the roof, inspect the ac unit "shroud," the protective cover. These are prone to taking hits from branches; plastic ones often get damaged by UV rays. Sometimes they can be fixed with fiberglass cloth and resin--check out a boat supply or auto parts house. If you repair cracks on the inside of the shroud, the work will likely be secure, but not obvious to outside observers. A more expensive solution is installing a replacement shroud.

The shroud should be securely mounted, you’ll find screws around the bottom of the shroud that tie it to the ac unit itself. Too much zeal with a screwdriver can easily crack the shroud around the mounting holes, rendering it useless. Take it easy! Firm, but not over-torqued is the rule for installing a shroud.

Take the screws out and carefully remove the shroud. Again, make sure you have the power disconnected--you don’t want the ac unit to start up while you’re poking around "under the hood." You’ll be looking for the evaporator--it looks like a small automotive radiator. Take a brush and gently remove dust from it--if you have an air compressor, gently blast the dust out with pressurized air. Getting the dust out will make your system more efficient.

Now check out the motor. Some ac units will have oil holes, possibly covered with a rubber plug. Other ac motors are permanently sealed and don’t require lubrication. For the former, carefully remove the plug and add 3 or 4 drops of oil--some recommend "three in one" oil for the job. Over-oiling is worse than not oiling! Replace the rubber plug(s).

Put the shroud back on, while keeping the torque down to a dull roar.

Wind It Up

Now it’s time to test the system. Be sure you have sufficient power--most ac units require your RV be hooked up to at least a 30 amp service. If you don’t have the power, wait until you get somewhere where a 30 amp circuit is available. Turn on the unit and let her rip. You should have plenty of cold air delivery. Enjoy a cool summer!