How To Service and Repair a Motorhome or RV Air Conditioner A/C

The rooftop air conditioners used on motorhomes are made to give many years of dependable cooling efficiency. But in order for the AC to operate dependably each season, it is necessary to keep the rooftop AC unit on your motorhome clean and properly maintained.

Occasionally the motorhome rooftop AC needs repairing and this article will assist you in knowing which parts of your RV AC to replace or service.These repair and maintenance tips are very simple to follow, even for those with less than good hands-on experience.

If you are unfamiliar with how a motorhome air conditioning system works, this article will help you understand which parts of the motorhome rooftop air conditioner unit to check, service, and repair.

Roof air conditioning units are the same as ones used on other types of RV campers such as travel trailers and pop-up campers. Your motorhome AC system may have one or two units to help keep the camper cold, or warm if the RV AC units have optional heat elements. These repair and maintenance procedures are identical for all types of the aforementioned campers.

After a few seasons of use, it isn’t unusual for the AC unit(s) to not cool the motorhome as quickly or as efficiently as it once did. Even though you have kept the filters clean on a regular basis, the evaporator and condenser coils will eventually become coated with dirt and grime which inhibits airflow and cooling efficiency.

Before attempting any maintenance or repairs on the rooftop AC unit be sure to switch off the electrical supply to the unit, either by tripping the breaker or by unplugging the motorhome from the electrical receptacle. You are now ready to remove the RV AC shroud by unscrewing the four bolts securing it to the RV AC unit itself.

After removing the AC shroud you will be able to see the evaporator and condenser coils on either end of the RV AC unit. If they appear similar to those in the photos at the right then they need a thorough cleaning. to allow unrestricted airflow through them. A good wet/dry Shop Vac will help to keep you from making a big mess during the cleaning regimen.

Although regular household cleaners may clean the coils to a certain extent, AC coil cleaners made especially for the purpose will remove the grime build-up much more efficiently and will not harm the coils themselves. Several types of these fine products may be found on this page.

Follow the instructions carefully for the best results and use the Shop-Vac to remove any excess cleaner or grime from the RV AC unit. Use a coil fin comb to straighten any bent fins because they too wull keep the airflow from moving through the AC coils. These fin combs are very inexpensive and may be used many times in the future on both RV and home AC coil fins.

While the RV AC shroud is removed, it is a good time to service the fan motor and clean the fans themselves. Whether your RV AC unit is made by Coleman, Carrier, Duotherm, or Dometic, it will have one fan motor which turns both the squirrel cage fan and the heat exhausting fan. This motor should be oiled at this time.

If your RV AC fan motor has regular bearings in it there will be oiling ports at each end of the motor. It may be necessary to remove the top metal sheeting from over the fan motor to access the bearing oiling ports. A few sheet metal screw will have to be removed to allow you to add oil to the ports.

If no oil ports are evident, then your rooftop AC unit has sleeves instead of bearings. You may still oil the shaft at the point where the sleeves are contained in the fan motor housing. The oil will seep inside and help the fan motor last much longer. A fan motor with sleeves cannot be rebuilt economically, as can the bearing models, and must be replaced with a new one.

If your AC fan motor is slow to start even after oiling, or needs a nudge to get it going, it will need rebuilding or replacement with a new one. As stated previously, a bearing model fan motor may be rebuilt fairly cheaply and will last for many more years. But not so a sleeved bearing AC fan motor.

If your unit seems to be in pretty good shape a new AC fan motor may be ordered to fit your particular RV AC unit. Check out the links on this page to find the type of fan motor you need to replace your model Click on the ads to look further on the Amazon site if you do not see your model of fan motor.

Replacement of the AC fan motor is a simple job with only a few tools required for the project. Mark the wire colors before removing the fan motor if the connection isn’t a simple plug-in type electrical connection. Test the new RV AC fan motor before replacing the AC shroud to check for proper alignment and fan clearance.

If the fan or compressor fails to start and the AC unit merely hums or trips a breaker, it is possible the starting capacitor is malfunctioning.  The capacitor stores electricity to give both the fan motor and the compressor an extra boost when the RV AC unit first starts.  It is not unusual for this item to go bad.

The capacitor is easily replaced in the event it has gone bad.  Note the wiring before removing the old AC capacitor and install the new capacitor in the same manner.  Your AC unit should now start and run fine.  Check the required voltage and model numbers on the new AC capacitor when ordering a new one.

If, after determining the switches, capacitor, and relays are not at fault, the RV AC compressor fails to operate correctly it is usually better to just junk the unit and buy a new one.

Unless you have access to a used compressor and have the means to replace it and recharge the system yourself, it will be too expensive to repair in most cases. Under normal circumstances the compressor will last much longer than the warranty covers.

The thermostat and switches may be purchased online by finding the correct model and serial numbers before ordering the new parts. These items w\are very easily replaced in most cases. Pay attention to the wiring connections as always when replacing these electrical components.

Your motorhome AC unit should give you many seasons of dependable operation if serviced annually. The use of a cover for the RV AC unit is highly recommended during the times when the motorhome is not in use.

These inexpensive RV AC covers protect the unit from being exposed to moisture, extreme cold or hot temperatures, and debris from storms, birds and insects. They will more than pay for their cost over time.

If your RV AC unit needs replacing, please see my article on how to install a new rooftop RV AC unit. Replacing your old unit with a more efficient RV AC unit is a very simple and quick procedure you can do yourself. Don’t be afraid to try these service tips yourself. You will learn much about these wonderful RV air conditioners.