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Air Conditioning Window Units

Car Window AC Unit

We've all seen the photos floating around the Internet of the cars with the home window air conditioners sticking out their windows and the massive amounts of duct tape that usually accompany them. Some even have very creative use of clothes dryer duct and other implements to enhance the aesthetic appeal of an A/C unit sticking out of a car window.

So... are those setups a joke, or do they actually work?

What Is Required To Set Up a 110V AC Unit In a Car Window

First, this is just a bad idea and not recommended at all. But some people are desperate and there may be semi-legitimate reasons to do this. The setup would apply to small camper trailers, pickup bed sleepers, and so forth. Obviously, everything you're about to read is used at your own risk.

To start, you need to know the power requirements of your A/C unit. Most likely it's a 120V (household) and probably pulling in the neighborhood of 400W. Amperage may be relatively high, but is likely less than 15A, which your car should be able to output.

Knowing these numbers, you'll need to figure in the needs of your car itself, since you will definitely have to run the engine as a generator to keep the battery powered while it's running this heavy load. Your alternator needs to be putting out enough power for the car plus the air conditioner's draw. Most modern engines (post-2000) use in the neighborhood of 1,200 watts while running, so your alternator needs to have an output of at least that plus your AC unit plus a little for fudge room.

Now, you'll need an inverter capable of converting the 12V of your car into 110V for your A/C unit. This is where it gets pricey as one capable of outputting 450W is going to be expensive.

So, if you have those things in place, you can run your window A/C unit in your car.

Setting Up the Window A/C In Your Car

Now for the jerry-rigging to get this to work. Figure out which window and realize that the rear of the A/C unit (where the condenser is) needs to be outside of the car as this is the part that gets hot. Having it inside defeats the purpose of the A/C. This means it needs to hang out the window or, if you're brave, the custom-cut hole you make for the unit. On a trailer or motor home, it will probably fit in one of the standard windows.

Realize that while the vehicle is moving, the unit needs to be removed and stored somewhere safe in the car and should NOT be running or used. Otherwise, you're looking at a real safety problem.

Once you have the unit mounted, plug in the inverter (or wire it to the battery) and plug the A/C unit into the inverter. Keep the engine running and give the shebang a test. If the engine cuts out when the A/C comes on, your alternator is definitely not up to the task.

If you have a meter, monitor the battery's load (it should maintain 10-12V while the car is running) to be sure the A/C unit isn't slowly draining it.

Now show off your ingenuity to your sleeveless friends and toast your success with some cheap domestic!

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