RV AC Overview: How Cooling Units Work

There are several different types of RV air conditioners in the market. First of all, we have the type that is on the roof here that just blows directly down, underneath, kind of like a window air conditioner in your home. We've got this model that sits on the top but it actually is ducted. So, it goes out to vents around the different areas. And then we have TrueAir which Winnebago brought out a few years ago, which took the compressors and put them down, below the floor and brought them up above.

And I brought Steve in here today just to give us a little idea of the overview of how the units work and a couple of things you can do to make them run more efficient so, Steve. Sure. Well, let's take the cover off of this rooftop unit. And basically, you've just got four components, four major components. You have a condensing unit onto this side which blows the heat, takes the heat out of the coach.

Out of the Freon. You have your evaporator, this is where all the work is taking place to give you your conditioned air. Now, an air conditioner could be something as simple as spraying some, air freshener in your coach. That's conditioning air. This is actually drying and pulling heat out of the interior of your coach.

So, that brings up a good point. There's a lot of people that think an air conditioner's gonna be dumping cool inside. It's got Freon, it's cold. It's gonna be dumping cool but instead, it's actually pulling inside air. It's a closed system.

Yep. And it's drawing inside air and cooling that down. It's actually, what's happening is, inside the evaporator, down at the bottom, on this particular unit you have a discharge duct which lets the conditioned air go into the cabin or the area you're trying to condition. And on the outsides of that duct, you have return air. So basically, what it's doing, it's bringing up the return air.

It's washing it through the coil of the evaporator which at that point pulls out moisture and drops the temperature, just actually pulls the heat out which drops the temperature. And then it discharges it through a small duct, either into that cabinet through the louvers in the ceiling or it blows it through the entire ceiling assembly through ports that they would have on an inducted roof system. Okay so, that's why it's important to understand that you can't take a unit like this that's sitting outside in 80 degree temperatures and let it bake inside 'cause it could get up to a hundred, 110 degrees. And then it really, from what I understand, it'll only be able to drop temperature about 20 degrees, typically. Yeah, 16 to 22 degrees is optimum.

Now keep in mind, ambient temperature, outside temperature has a impact on that as well as the interior temperature. If you have all your windows closed, what's gonna happen? Say you start out at 96 degrees. The return air is gonna pull that 96 degrees in. It's gonna run it through the evaporator coil.

It might drop it two degrees. It's gonna extract some moisture. Now that air that's coming out instead of 92 might be 91, 90 and it's just going to keep re-circulating, as long as you keep the windows closed, the doors closed and it recirculates that temperature is going to continually drop. The differential between your intake air that's coming in from the cabin, to the discharge air that's coming out of the air conditioner into the cabin will be about 16, like you said, to 22 degrees. And that is about the most efficient any of these units will do, but it's continually, keep in mind, that 16 to 22 degrees is constantly being lowered as the return air cools down, so does the discharge air.

So, that's why it's important to understand that you can't just come in here, turn this on and then five, 10 minutes, expect it to be down into 75 degrees. No. So, you're gonna have to find some shade. You're gonna have to make sure you vent, some of the roof vents are open, drawing some of that heat out and just understand how this works to make it run more efficiently and cool your unit down.