As we approach the dog days of summer, we find ourselves “recreating” in some extreme temperatures and high humidity conditions. In our homes we can maintain a comfortable temperature just by setting the thermostat and not worry about it. Every time we walk into the house the temperature is the same. Too many new RV owners expect the same performance from their RV roof air conditioner and become frustrated when they step into an uncomfortable rig!
To optimize the performance of your roof air conditioner and help it run more efficiently, you need to understand how the system works, what limitations it has, and how surrounding factors can affect your overall comfort.
How the System Works
The compressor “compresses” the refrigerant into a vapor and then the condenser removes the heat and condenses it to a liquid. As it passes over the evaporator coils, heat is drawn from the return air to make it expand vaporize. The removal of heat from the air provides the cold air to the RV. The system is completely closed so there is no “recharging” refrigerant like you would do for an automotive system.
The biggest culprit in low cooling in an absorption system is a dirty return air filter or even dust and contaminants in the cold air return. You should clean your cold air filter every two months and check the return air for signs of dog hair or even dust.
If you have a ducted roof air conditioning system, the cold air return is usually behind a vented grate in the ceiling and the ductwork is embedded into the ceiling.
To make your roof air conditioner operate at maximum cooling capacity, here are some tips:
1. Make sure your filters are clean and unobstructed. Clean them in lukewarm water with a mild detergent and rinse thoroughly, and then let dry overnight. You can also use an air compressor to blow them out as well.
2. Verify the air return to the A/C unit is not clogged with dirt or other contaminants.
3. Check the condenser coil up on the A/C unit to verify the coils are not obstructed or pinched and will let the fan blow out hot air to the outside.
4. Make sure you have at least 115 volts of A/C going to the unit. Low voltage at the campground source will still allow the unit to operate, but not at maximum capacity.
5. Park in the shade. Getting out of the sun can mean a temperature change of over 20 degrees during hot weather. The roof air conditioner can only cool the ambient inside temperature about 20 degrees, so if it’s 100 degrees inside the rig, you will only be able to cool it down to 80 degrees if everything is working perfect!
6. Keep the window blinds down and windows shut (again, getting the inside to cool down by insulating the windows and not allowing the cool air inside the rig to escape).
7. Limit the use of heat generating appliances such as the stove top, toaster, oven, and even the microwave which will exhaust hot air into the coach.
8. Add fans inside the rig to circulate air help get rid of “pockets” that air sits and gets warm.
9. Develop “zones” that need to be cooled and those that don’t. You may not be able to cool a 40’ rig when the temperature is 110 degrees outside, so close off the bedroom and bathroom and close the ductwork if available and have both air conditioners cooling the living room and kitchen. Then cool the bedroom at night when the temps go down and zone off the living room.
10. Install LED lights as they not only draw about 10 times less power, they run about 10 times cooler.
11. Use the patio awning and window awning to help provide shade and a cooler interior.
12. Install a MaxxAir roof vent cover and bring in cooler air when temperatures are good, and exhaust hot air out during the heat of the day.
Now that you have a better understanding of your rig’s cooling system, hopefully you can use some of these tips to make yourself comfortable. Stay cool!
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