Thursday, June 1, 2023


A/C concerns in long-term shady campsite for camp hosts


gary-736Dear Gary,
We start our first 8-week camp hosting activity in a few weeks. Our campsite is very shady with hardly any sunlight making it to the ground because of all the trees.

My real concern is our air conditioners will always be wet/moist causing mold/mildew to form. One of our A/C units has duct work throughout the roof. I can just imagine having mold spores flying through the duct work then ending up inside the trailer for us to breathe. Also, will our roof and awnings end up getting very nasty? Am I overly concerned? Please help! —Gene Bennington

Hello Gene,
The important thing to know about RV air conditioners is that they really don’t “make” cold air. Their sole design is to remove moisture from the air inside the RV. This particular process of refrigeration causes the air temperature to go down. I don’t think you’ll have anything to worry about concerning being in a shady enclave in the campground since the process is centered on lessening the moisture content of the air.

It’s also important to realize that heat cannot be destroyed. In an air conditioning system, the heat is simply moved from one place to another. And heat always moves from a hot area to a cold area. The same with an RV absorption refrigerator. The process of absorption removes heat from inside the refrigerator (and its contents) to the exterior of the refrigerator. In an air conditioner, this process of thermodynamics is propelled by a compressor and the refrigerant through a condenser and evaporator inside the sealed system.

Whenever a refrigerant is compressed and heat is removed (as in the air conditioning condenser), the gas will lose heat as it liquefies. As the pressure on the liquid is reduced (entering the evaporator), it returns to the vapor state, minus the heat that was lost in the condenser. The absence of heat makes the evaporator cold. And since the laws of physics make heat travel to cold, heat from the interior of the RV is absorbed by the refrigerant in the cold evaporator and carried to the compressor, which forces it into the condenser, where it gives up the heat to the outside air. The air is sucked from the living area by the spinning evaporator blower wheel that also passes the cooled air back into the RV. That’s a complete cycle: The refrigerant picked the heat out of the interior air (where it was objectionable), through heat absorption, and released it using the properties of evaporation and condensation.

You might have to read that paragraph a couple of times, but the bottom line is this: There should be no undue moisture forming regardless of the lack of sunshine. As the removed heat condenses and is released to the roof of the RV, it will either evaporate or simply roll off the sides of the roof. In a sunny location, this happens quicker, of course, but the formation of mold is rare in a normally operating A/C system.

The key is to keep the air conditioner evaporator and condenser coils clean. A clean return air filter is also vital for proper operation. Once a year, take the cover off the roof unit to inspect the condenser coils and remove the ceiling shroud or plenum inside the coach to inspect the evaporator. You may need a flashlight for the evaporator to be seen clearly. In rare instances, the coils will require cleaning. The filter is always located within the path of the return air to the air conditioner inside the coach. Keeping it clean will keep the evaporator clean in most cases. You should be good to to!

For the awnings, the operative words are “clean” and “dry”!

Hope this was helpful to you. Remember, RVing is more than a hobby, it’s a lifestyle! —Gary

Read more from Gary Bunzer at the See Gary’s videos about RV repair and maintenance.



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5 years ago

Yes, yes, yes, your awnings and outer skin will absolutely get a coating of mold. And so will your Windows and interior window frames. We suffered through it in GA, where one side was close to a cabin and never saw sunlight. We kept the shades drawn for privacy and rarely ventured over on that side…boy, were we in for a rude awakening when we packed up after our 4 month gig. Keep em clean and dry and you will minimize the issue.

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