Author Options:

What to do with an old A/C unit? Answered

I have recently purchased a new window-mount air conditioner, and now I am looking at the crappy old one saying "I can't just throw this away after having read the Dumpster Dipping instructable!" Any ideas on how to reuse/recycle this horribly used (purchased ca. 1988) A/C unit that hardly puts out cold air anymore?


Hmm... you could open it up, remove all the nasty grimy dust, try it again, and if that doens't help its cold-air output, see about getting it professionally drained (although I bet it's drained already due to the lack of cold air, draining A/Cs is not a home project), then use it as an electric air compressor. They're actually pretty handy for that.

I've been thinking of hooking a wind turbine straight to the shaft of the compressor to make a co2 neutral cooler. If you do take it apart use the blower fan for a small wind turbine.

...thinking of hooking a wind turbine straight to the shaft of the compressor...
Wow. Since window air conditioners have all the compressing stuff sealed inside a heavy steel shell with just the electrical connections going thru it, that would truly be impressive. Well, best of luck!

. Yep. The shell is part of the suction side of the pump. Have to have a good mechanical face seal (ie, expensive and alignment of the stationary member would be difficult) where the shaft penetrates. Certainly not impossible, but probably not practical for a DIYer. I'd try to find a compressor designed for an external driver.

????? Have we been tearing apart the same type of air conditioners? I find a metal cylinder with rounded ends, just inlet, outlet, and electrical connections. Smooth down the sides with a grinder and it'd make a good cannon projectile.

. Right. The compressor motor (another good source of Cu, BTW) is sealed inside the metal cylinder (shell). To use an external power source, you would have to pierce the shell.

Or just follow the wiring diagram with the AC unit to hook up the capacitor and power lines to the compressor and plug it in? :-) (And now I'm reading killerjackalope's comment and wondering if "throwaway" window units are getting confused with central AC systems...)

. LinuxH4x0r and I hijacked this topic and started talking about using a turbine to drive the compressor. . . Central units and window units are essentially the same, just the former having the evaporator further from the condenser/pump. All units I've seen have a sealed compressor (to reduce fluorocarbon emissions?).

Look down, at the comment I posted, it's got a solution to the motor replacement problems and to the drive... Plus it's better use of space...

And... I'm still confused. I could get a pulley on the shaft of the double-ended blower motor, but as I've yet to crack open one of those compressor / motor units I fail to see how to add a belt drive. Or how to extract the motor for a disco ball. Or how to even make those small sputtering things into a "carbon neutral cold air pump." For all I can tell, there's one or more sliding pistons in there being driven like a solenoid plunger, no shaft at all! Things almost make sense if we were talking about a compressor similar to an automotive unit with an electric motor on the other end of the shaft, the combo then sealed inside the heavy shell, but it'd be constructed so tightly together there would be no available shaft to work without removing the motor part, which is likely an integral structural piece as for compactness within that small sealed shell the shaft can be supported with one outside bearing on the compressor end, one on the motor end, and that's it. Both motor and compressor could actually share a housing, a true integrated unit, under that shell. That would be the best engineering. And there is no freon tank. If I was to ever pursue a wind-driven "carbon neutral" cold air pump, I'd start with an automotive supplemental air pump (smog pump). They spin easily and take pulleys. They also generate enough air pressure to counter the outgoing pressure in an exhaust system, while an A/C compressor generates even more pressure to liquefy the refrigerant. That just adds inefficiency as it's unnecessary for the application.

At some point I had started thinking about fridges aswell, that's probably why that was so confusing... The smog pump would be easier to drive by the sounds of it, the idea of the carbon neutral one is simply to replace the drive of the motor with the output from a windmill or a waterwheel maybe, I suggested using the motor since it's not being put to use by that but could be used as a generator instead... I haven't seen the unit so I'm not really sure about how it actually looks and is laid out. I think the best actual use for this may well be as a vacuum pump or compressor...

I think the best actual use for this may well be as a vacuum pump or compressor...

Long long ago, my father used an old refrigerator sealed compressor for a portable air compressor, good enough to pump up tires, remember it from when I was a young boy. You know, just ten years after the last T-rex was killed? Then he got ahold of a small piston air compressor, hooked it up to a motor and mounted the assembly up in the rafters of the garage, later mounted a wall switch instead of just plugging it in, then used plumbing parts and air line quick disconnects to use two old propane tanks for pressure tanks. Then when I was working and thought I had money, I got a large horizontal 240V portable cheap, needed a belt, and the rest just went away. Except for that little former refrigerator compressor, which had been tossed out almost two decades before.

I can get a 12V that will pump up my truck tires in about 10 minutes at Wal-Mart for $10. A small contractor-type portable with tank(s) isn't that much money, unscrew the air filter and use some plumbing parts and call it a vacuum pump.

Spend the $10 and scrap the old A/C compressor. Between the scrap money and not buying the fittings you'll actually end up ahead.

You could make a small but actually quite useful compressor or vacuum pump...

As linux said you could do the carbon neutral cold air pump... However you could do this by adding a belt drive, in the same fell swoop you can make it do cold air and generate some electricity.

The motor for the compressor could be of use in a project like a massive disco ball or similar.

The freon (or whatever other compound) tank can be used as a little air reservoir, which can be pretty handy.

The pipes inside can be very useful for small bodge jobs in other projects.

To give you an example of random things I have now gotten through all the parts of a blown Xbox PSU, very little of the parts were used in making electronics, the magnet wire was harvested and kept for that though... But back on topic, with a little thought almost every part of something can be reused, the casing and frame can be excellent support structures or cases for another project.

If it's low on refrigerant it likely can't be recharged, thus is no good for that.

Take off cover. First off, identify the Very Large Capacitor, short terminals with metal screwdriver while holding the plastic handle. If the design prevents shorting with a straight piece, you can use two screwdrivers, one on each terminal, and touch the shafts together. I've also used needle-nose pliers. After you're certain it's discharged then pull off the wires.

For that age I'll assume it's not digital, so you have a nifty mechanical switch that goes on at the temp setting (thermostat), be careful with the sensing bulb (normally is one). There's the power switch, large capacitor, and the cord.

I recommend bolt cutters, the long-handled ones. Snip off one large refrigerant line near the compressor, higher is better. As it probably was charged with R-12 and related refrigerants that were later banned due to their ozone-depleting nature, venting to the atmosphere is verboten. You can hardly throw out old AC's and refrigerators as many garbage haulers won't take them unless they're drained, which must be done by qualified personnel who'll remove the refrigerant without venting, let alone taking them to a scrapyard. The long handles will keep any escaping refrigerant from freezing your skin on contact (!) as may happen with a hacksaw or tubing cutter. Don't do that near flames as toxic gases may result. There will be some oil in the system, some spraying, so cut high to minimize, drain and discard the oil later.

Now you can use a tubing cutter for nice ends. If you can figure out the wiring you might be able to rig up the compressor for air, but small air compressors are so cheap nowdays it's not worth it. Since there's a motor inside you might try cutting it open and recycling the copper, but that's much effort. Well, with a few cuts you have the two refrigerant cores which perhaps you can use with water for heating and cooling purposes, and at least they're now in a form that gets a good price as scrap.

The motor uses the capacitor to run, if you can figure out the wiring then it's usable and multi-speed to boot. Otherwise scrap. The squirrel cage and outside fan are of course usable, if you can get them off the shafts without breaking.

Then you'll have some plastic normally good for throwing away, sheet metal, other metal for scrap, and lots of screws and little bits for future projects.