Converting a freezer to an A/C unit

Many of you have no doubt heard that parts of Europe are having a pretty bad heat wave.

What with one thing and another, it is neither practical nor economical for me to buy an A/C unit right now. For one thing, the available ones suck. We had one where I used to work, so I know the short comings of the typical European A/C unit. For another, they are are too expensive - and right now, I’m not sure I could even find one to buy.

I don’t think I’ll do it, but for the last few days I’ve considered going to the dump and getting an old refridgerator with a freezer compartment and rigging an A/C out of it. The biggest thing stopping me is knowing that it would (at best) look like a piece of junk, and the wife won’t let me keep something like that around.

Aside from certain mechanical problems - which I can figure out how to handle - are there any reasons why it wouldn’t work?

What kind of duty cycle is a fridge compressor rated for? I would expect the rig to have to run hard to cool off this big rock pile - even cooling just one room would mean cooling the warm walls. That’s one thing I see as a problem - the compressor not being up to a long time running.

A thermostat wouldn’t be a requirement - cheap and simple would be the rule, and I could turn it off if it should ever approach being too cool.

I could tear it apart and put the compressor and evaporator outside, and run the lines through a board I could put in the sliding door, so separating the hot from the cold could be done.

Would the cooling coils be a problem? Would they tend to freeze up, and would it help to keep a strong air flow over them? I expect that at the very least I’d need a bucket underneath to catch the condensing water.

Anyone ever done this before, or have any ideas about how to do it?

Refrigeration theory is the same for AC units as refrigerator units and the hardware is basically the same, just on different scales. You would have to put the compressor and the condenser coil outside. The condenser has the job of losing the heat. You would need additional refrigerant lines to go to the evaporator which would be inside. Its job is to absorb heat. Here in America, residential freezers and refers use aluminum tubing rather that copper. I don’t know how to braze aluminum with out burning it. Also, would additional refrigerant be available to you? You would need a fan or blower across the evapoator to keep it from freezing. It would, however, be way too small to cool a room.

OK, that was the answer I was looking for. Not enough capacity for the job.

It looks like I muffed the terminology, too. Evaporator (cold) inside, condenser (hot) outside.

Oh, well. At least it was fun thinking cool thoughts about having A/C again.

I don’t see you needing to weld or add refrigerant, so long as each bit is nailed to opposite sides of a board. Taking it apart seems complicated and dangerous, as releasing/replacing refrigerant isn’t my idea of a fun project.

I can’t find any duty-cycle info for 'fridges, but I hear they almost never break in regular use. Perhaps you could use the supplied one and modify it for higher temperature use. So long as the motor got a 10 minute break every now and again, I don’t see it breaking down before your wife does. :smiley:

I was hoping to not need to cut or solder the (copper) coolant lines. My thought was to remove the housings - cutting them if need be to spare the coolant lines - and then place a board in my sliding glass door between the door and the frame. The coolant lines run through holes in the board, with the lines (carefully ) bent as needed to let things sit evenly.

So, how many BTUs of cooling power does a fridge have, anyway?

What about leaving an old fridge/freezer running (outside of your house/apartment, of course - it would be a heating appliance else) and using it to

  • cool down your clothes

  • cool down Kühlakkus - don’t know the English term; the high-thermal-capacity packs you use in a cooling box without its own energy supply) and take them to bed with you

  • run a hose in and another out of the fridge; attach a small electronics-type ventilator, direct cool air where most needed

That’d be one way to go. 29 degrees Celsius in the house is just getting rather old, and I’d really like it to cool off.

Just replace your outside door with the refrigerator sitting on your porch facing (sealed right up against) your door opening. No need to modify the fridge, but what are the odds of finding a working unit in the dump?

Duty cycle? I just found that my fridge was set to 9 (run continully) for about 10 months, it still works fine, actually got colder when I put it in th emiddle due to disapation of heat in the back.

Combining Google with my limited Deutsch, I think the closest English equivalent would be “ice pack”; we freeze them and put them in what we call coolers, which is odd, because by and large, I have seen very few coolers that actually cool – that is, most coolers are just insulated storage chests that don’t have a power supply. That’s what threw me at first when you said “cooling box without its own energy supply”. Of course, this is American and not British or Continental English, YMMV, etc.

The compressor and coils on a residential refrigerator provide about one eigth of a ton of refrigeration. The typical window unit is about one or one and a half ton.

What does a ‘ton’ mean in this context? To me it means 1000kg, but that doesn’t quite seem to make much sense…

That’d be the easy way to do it, all right. Actually, the odds are pretty fair on finding a workind unit at the dump. I call it a dump, but it is more of a recyling collection point. The stuff doesn’t stand around and rot and rust for too long - if there’s one there, then it hasn’t been there for long.

Contrary to the environmental conscience that you hear attributed to Germans, there is a rather strong tendency to dump perfectly usable furniture and replace it with the latest “in” thing. It is common to find furniture put out on junk pick up days that is in perfect condition - but just too old and not “modern” enough.

Our living room furniture came to us that way - my wife placed an ad in the paper looking for a living room set for free. The first day the ad was out, we had calls from several people looking to get rid of their “old” furniture to make room for the new stuff. All it cost us was going to pick it up. We’ve got living room furniture in good shape that cost us a couple of bucks in gas - and when the kids (5 years and 2 years) rough house on the furniture, I can dress them down for breaking the rules instead of being pissed at them for jumping on our expensive stuff. When the kids get older we’ll buy new stuff, but by then the old stuff will really need replacing.

I think this kills the idea, though:

The only room in the house I could do this in is the livingroom/dining room - one big room about 15.5 feet by 33 feet. This would be a big job for a window unit, and it is made worse because of the way the house is built. The walls are made of blocks like cinder block about 12 inches thick, and have an inch of plaster on the inside and a couple of inches of stucco on the outside. To cool the room, you’d have to eventually cool the blocks - and that’s an awful lot of mass to cool.

The worst of the heat seems to have passed now. Temperatures outside were a good 18F lower than they were yesterday. The house itself hasn’t cooled much, but it will if the temps stay down.

I have successfully turned an old freezer unit into an ac that cools off my 8x10 shed using nothing more than the lines in the freezer, some solder a length of pvc some expanding foam and a couple 2x4’s and ply wood and an old hardshell suitcase, a small fan and some silicone caulking .

The shelves in the freezer were the coolant coils so I cut them out and dismantled the unit and put the 5 cooling coils inside the suitcase and used the copper lines to connect them and placed them in a condensation pan I made from some old milk jugs and cut holes in the suitcase to mount the fan, condensation drip line and run the refer lines.

I cut a small hole in the wall to run the lines through the pvc pipe and filled it with expanding foam and attatched it to the suitcase inside the shed.

Next I built a shelf and housing for the compressor to sit on and ran the 2x4’s up so to mount the outside coolant coil. i used the temp control from the freezer and mounted it on the wall and soldered it all together and it works like a charm.

Granted I have to turn it on and off manually but it cools my 8x10 shed perfectly. It just depends on the coil configuration. And how much room your working with. I don’t think it would work on a room any bigger than 8x10.

But yes it is possible.

To the OP: The cooling coils are inside while the compressor and coolant coil are outside. Otherwise you are going to simply heat up the room more.

To DenisZen: You are a mad genius. Why did you need a 8x10 refrigerated shed? Or do I not want to know?

The heated coils are mounted outside with the compressor and its my fortress of solitude.

And thank you for the compliment, I appreciate you noticing. :blush:

The OP hasn’t posted since 2004, so it’s unlikely they’re going to see your reply…

My BIL did something like this for a garden shed, but he put the whole refrigerator outside under a shed roof where he parked his lawn tractor. He then ran two pieces of 6" flex duct from the shed to the unit’s door, where he cut two 6" holes (one high and one low. Finally, he put a fan in the shed on the duct that ran to the lower part of the door so it pulled cool air into the shed (i.e., the duct to the upper part of the door was the return air from the shed). He just caulked all the seams.

It was a small undercounter unit and the cooling was quite effective. I believe he ended up putting some metal scrap in the refrigerator so there was a cold mass and not just cold air. When the weather got cooler, he just propped the door open slightly and let it sit there for months at a time. I don’t remember if he covered it. I will also mention that I could not force the door open when the fan was on because the negative air pressure inside the unit was significant.