Making my own APU

Can a roof mounted A/C unit like the ones you see on RVs be mounted on the back of the cab? If not then why? Thx!

 

They can be mounted on top but I don't think you could mount them vertical on the back wall if that's what your asking. I'm not 100% sure but I think the way they are made to operate would prohibit them from being mounted vertical. I think it has alot to do with the compressor and freon. Kinda like if you put a fridge on its side or back to move you are suppose to wait for several hours before plugging it back in.

 

That's about the only way I would even consider buying one of those.

 

In 1985 I mounted a vw rabbit diesel motor behind my cat in my k100 110" coe. Tied into the fuel and water off the cat and into the a/c of the truck worked great for 10 years. Early apu heat and a/c for very little.

 

How in the world did u do that ??? I bet was ingenious but did u build a box ? It was enclosed ? How noisy was when running ? What about weigh ?

 

The vw sat on the frame rails behind the cat coverd by the cab (110") teed into the truck a/c and heater hoses wired the fan to run key off. A muffler kept it quite and an alternator charged the batts. and a compressor kept it cool and hot water kept it warm, it weighed about 150# or so. start and stop inside, I was proud of it and we rigged 3 all togather the engines were hard to find.

 

Also Colman makes a roof top called the roughneck that can be mounted veritcal, cost about 2k

 

I know I'm bringing this from dead but has anyone considered using a fridge's guts to cool the cab? Its all electric?

 

A window AC is cheaper than a fridge.

Every year summer starts creeping near these dead APU threads get dug up.

 

These threads aren't dead. Just rescued. I just installed a 12,000 btu with a Honda 3,000 gen. In my kw. a/c is one of those that sit on the floor and you run the exhaust hose to a window. Sat it on my top shelf I built that replaced my upper bunk. Does a great job of frosting my windows up in 80 deg. Weather. One thing I also did was had a vinyl letter place cover the top of my bunk with white vinyl. Made a big difference in what heat is absorbed through the roof on a sunny day. $2400 in the gen and a/c. Probably another $500 in everything else. I don't use one that much but I just don't want to idle my new overhauled engine.