RV A/C Overview: How Cooling Units Work
RV Lifestyle & Repair EditorsDescription
There’s a fairly common misunderstanding about the capabilities of RV A/C units in the sense that many RVers expect them to cool a hot vehicle in no time flat. After returning from a hike on a 95-degree day, my RV should be cool and comfortable as soon as I kick on the A/C, right?
That would be pretty great, but it’s an unrealistic fantasy. The fact is, that’s not how air conditioning works. In this lesson, we dispel the myth of the magical RV A/C unit, teach you how these appliances actually operate, and give you a few important tips for making your unit run a little more efficiently.
What Goes on in Your RV A/C Unit?
To help you better understand how your RV A/C unit works, RV maintenance expert Dave Solberg and RVIA Master Technician Steve Albright walk you through a quick overview of the types and functionality of the air conditioning units found on most vehicles. Whether you opt for a roof-mounted, duct-driven unit or a newer model that sits underneath the carriage of your motorhome, it operates in generally the same the way.
There are four major components that make up an RV A/C unit, each of which Steve inspects on a demonstration model. The evaporator is the most essential part in the cooling process, responsible for pulling warm air out of the vehicle and slowly recirculating it to drop the temperature by small increments.
Making Your Unit More Efficient
Addressing the belief that A/C units should be able to instantly cool a space, Dave and Steve talk about the limited capabilities of all units, regardless of quality, cost, and type. There’s simply no way to make the temperature plummet. So what can you do to help your RV A/C unit run more efficiently and expedite the cooling process? First and foremost, get your vehicle under shade—stat! Limiting sun exposure will keep your baseline temperature lower, and you’ll get comfortable much quicker! Keep your RV in the shade as much as possible throughout the day.
There're several different types of RV air conditioners in the market. First of all, we have the type that is on the roof air that just blows directly down underneath, kind of like a window air conditioner in your home. You've got this model that sits on the top but it actually is ducted so it goes out to vents around the different areas. Ceiling. And then we have a true air 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 Steven 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 efficiently. So Steve. Sure. Well, let's take the cover off of this rooftop unit. And basically you've just got four major components. You have a condensing unit on this side which blows 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 is 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 and it's drawing insight air and cooling that down. Actually what's happening is in 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 discharged 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 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 100, 110 degrees and then it really... From what I understand it 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 shifts going to keep recirculating. As long as you keep the windows closed, 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 and 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 fencer open drawing some of that heat out and just understand how this works to make it run more efficiently and cool your unit down.
My 1999 fleetwood a.c.,s arooftop first a.c.,has 2 wires 1 black,1 white. Coming out opposite wall all runs however no cool at all?
So its OK to have roof air vents open when running the AC? I understand the sense of having doors and windows closed, as well as that hot air rises so it would make sense that the hot air in the RV would travel out of the roof vents. But how long do you leave them open? Just a short time?
The roof air conditioner on our '72 Winnebago Scrambler has slowly stopped cooling. Can anyone recommend someone in the Minneapolis area that might be able to check it for leaks and then put new coolant in it? We last put coolant in it back in the mid-90's, which got it working fine again, but now the original type freon is not commonly available, plus the air conditioner might have developed leaks since then. It worked somewhat two years ago. We haven't used it very often, as we don't travel much in the hottest part of summer, plus have a ceiling exhaust fan that works wonderfully, but there are times the air conditioner comes in handy.