[retrodog]

Yeah, I'm a noob here so maybe there is a thread that you can point me to.

I'm in the planning stages of doing a car conversion and since I live in the Houston area there would be about 6 months that I need ac of some sort. I'll probably be using an RX-7, Miata, or MR2 so I won't need tons of cooling. I've seen some 1.5 hp motors for running the ac compressor and power steering pump. Do these work or is that inadequate for this work load?

Also, do I just build a new bracket system for mounting the existing compressor and pump so that the existing plumbing reaches adequately?

I have a small machine shop (drill press, cut-off saw, MIG welder, etc.) so I could custom-build the brackets.

 

[Greenflight]

Hey retro- there aren't a whole lot of guys running A/C, so you're kind of on your own here.

I would imagine one of those small Ametek tape drive motors would be adequate. Can't say for sure though.

And of course, if you want to fill it with ice every so often: http://www.instructables.com/id/Portable-12V-Air-Conditioner---Cheap-and-easy!/

As far as power steering goes, I've never thought that it's really necessary. Especially on cars in this size range. Heck, I drive my truck without it.

Good luck!

 

[moldiebrownie]

Like greenflight says, alot of guys don't run it because of the extra weight and or battery drain. Those that do, either run the compressor from a small electric motor via a v-belt like this guy http://www.geocities.com/electric_honda/civic/civic3.html
or they buy a dual shaft drive motor like this http://www.evparts.com/shopping/product_details.php?id=536&product_id=1123 and install a pulley on the other side to drive the compressor like this guy http://www.saabrina.blogspot.com/ who is actually running a/c and p/s off it.

One other alternative (of which I know nobody doing it yet probably because of price and availability) is to use one of the new compressors from Nippondenso that comes stock in some hybrids. Denso has married a electric motor to a compressor in one neat package. They did this because when hybrids stop at a light or something..the gas engine is off and the traditional belt driven compressor will not function..hence no AC. For the same reason...there are now electrically driven steering racks. Here is link to one of these compressors being sold on Ebay http://cgi.ebay.com/ebaymotors/2004...ressor-OE_W0QQitemZ320015485444QQcmdZViewItem
This particular one is Toyota part # 88370-47010 and happens to retail for $961.58 (US) new at a Toyota dealer. If you do go with a regular compressor and run it off a small electric motor...you can use a very small compressor like from a Geo metro since you say you don't need much ac. I attached a pic of the Denso compressor since after the ebay auction the link will be useless.

 

[pandaran]

And of course, if you want to fill it with ice every so often: http://www.instructables.com/id/Portable-12V-Air-Conditioner---Cheap-and-easy!/

That's genius! I was wondering how I'd get a/c, and that looks like a distinct possibility! Plus I like the cheapness. ^_^

 

[KiwiEV]

I like that idea too. It's almost summer here and I'm keen to try and make one myself out of foil-lined flexi-pipe and a big chilly-bin. The next EV will definitely have proper air conditioning for those 2 or 3 months of the year that it can be uncomfortable to be sitting in traffic with your back adhering to the seat.

I also just thought of something to make it even more impressive - buy "dry ice". Dry ice is simply frozen carbon dioxide. It's cheap to buy, stays cool a long time in a chilly bin and is something like -70° C (-94° F) when frozen. A bag of it would last a few days in a chest at home, and you just pour some into your portable cooler when you're heading out. It evaporates leaving no moisture too so there's no water to remove!
I like it! I think I'll try that this summer!

 

[pandaran]

So, would you just have dry ice in a box with fans blowing the air out, instead of having the water circulating through the heater core?

 

[KiwiEV]

Oooo that's a good question. I haven't thought of it in detail. The idea bowling around in my head is that You'd have a large chilly bin in the back seat with some foil flexi-pipe - like you use with home ventilation systems - running between the front seats and aimed at the driver.

Let me whip up a picture of what I had in my mind...

There! It's very simple but you get where I'm coming from. Perhaps having the air travel through a sealed metal box at the bottom of the ice water would help too? For me to create it, it would have to be ultra simple and cost effective too.

 

[elevatorguy]

So, would you just have dry ice in a box with fans blowing the air out, instead of having the water circulating through the heater core?

I'm not a chemist, but wouldn't that be piping carbon dioxide into the car?
I think keeping the dry ice in a bin and exchanger would be a good idea

 

[pandaran]

I like the idea of the dry ice being colder, but the thing that really draws me to regular ol' water ice is that I can make it in my freezer, or stop off at any sort of Kwik-E-Mart for more along the way.

Of course, I'm completely new to these sorts of projects, and it would be wonderful to see a different take on that a/c. More options = good!

One thing that would be nice is finding a way to make the ice last longer. The long drive I make the most often is to Sacramento and takes me a bit over an hour and a half. It'd be annoying to have to stop on the way for ice. Then again... I still have to do research to see if I can get that kind of range on an EV in something resembling my price range in the first place. (I love your on-the-cheap take on things, Mr. kiwiev. I'm already planning on implementing your heater design! ^_~)

 

[KiwiEV]

Hehehe, you're very welcome. I should find out if the heater works this weekend if I can get all my main cables in. I'll blame Nick Smith if it doesn't work.

 

[Mr. Sharkey]

I just have to poke my nose in here and kick my own A/C system. Depending on what type of car you choose to convert, you may not need to do too much of anything to take advantage of the cooling power of ice:

That's two bags of ice cubes in the "rain tray" of my VW Rabbit EV, with room for at least two more. All of the air that enters the car's ventillation system has to pass over the ice on it's way into the passenger compartment. No pumps, no additional circulating fans, has automatic melt water draining, the whole works, built in at the VW factory!

 

[mattW]

I wonder if it is possible to kill two birds with one stone by combining the pressure pump for the AC with the vacuum pump for the brakes. I realise that AC is usually using freons or something instead of just air. But it seems stupid to have one pump to bring things up to pressure and another to bring other things to low pressure. Does anyone have any ideas about how to combine these two functions? Is there such a thing as a pressure exchanger like you can do with heat? It might even make the vacuum pump a bunch quieter!

 

[pandaran]

Awesome! How much would you say it cools the passenger compartment with passive cooling like that? It gets pretty toasty here during the summer (105ºF/40ºC+) and a/c can be more than just a matter of comfort on some days.

 

[Mr. Sharkey]

It's not like having "real" A/C, but neither is one of those cooler units. Just having some cool air blowing on you can help. Personally, I would refuse to live anywhere that the temperature extremes require life support.

 

[pandaran]

Haha, yeah... sometimes it's a pain, and I definitely don't like the sheer number of people (since most of them are grumpy too much of the time), but it's sure nice to be within a two to three hour drive of the ocean, the snow, lakes, mountains, rivers, and desert! Although, I haven't really had a huge urge to visit that last one.

 

[Nick Smith]

And if it does work you can all address the checks to me... I need lithium (ion) for my condition.

 

[mattW]

Ok here is my idea for relatively efficient AC based on no experience and a dodgy knowledge of what it is I'm talking about. Get a slightly larger vacuum pump then you would have otherwise and install a really small used turbo on the 'exhaust' of the pump. Rather than using the turbo to compress the air going into the engine you could use it to compress the gasses in the air conditioner. This is based on a bunch of assumptions but it works in my mind. I'm a bit worried about the scale of the turbo to the amount of air exiting the vacuum pump and also whether or not the turbo even could be used to compress AC gas but if it could work, or could be made then you would only be using slightly more energy to do twice the work. What do you think?

 

[xrotaryguy]

I wonder if it is possible to kill two birds with one stone by combining the pressure pump for the AC with the vacuum pump for the brakes. I realise that AC is usually using freons or something instead of just air. But it seems stupid to have one pump to bring things up to pressure and another to bring other things to low pressure. Does anyone have any ideas about how to combine these two functions? Is there such a thing as a pressure exchanger like you can do with heat? It might even make the vacuum pump a bunch quieter!

You can do this with the power steering pump and a hydo-boost brake booster. You can't do this with an air conditioning compressor.

 

[xrotaryguy]

I think you guys are on the right track with the ice in the cowl. This is similar to keeping the ice in an ice chest and blowing air through it. Here in Arizona, many golfers actually buy systems like this for their golf carts. Here is one example.
http://www.swampy.net/golfcartairconditioner.html

The unit on the top blows cool air onto the cart's occupants while the ice chest in the back supplies the icy cold reservoir of ice. This system uses a 12v fan to move the cool air, but it has no capacity to freeze the ice.

I think that the best way to go would be to install a small recreational electric ice chest that can be run off of a 120v household ice chest. That way it can refreeze the ice when the car is charging.

I wouldn't simply toss an ice chest into the car and run an extension cord to it though. I would probably fill the ice chest with water and submerge a heater core in the water. The heater core would have antifreeze in it and would be plumbed to the car's evaporator core or to its heater core. Using the evaporator core would probably make more sense. That way the air conditioning controls/vent doors, etc would still function properly. A small fluid pump would be required to move the antifreeze. The car's stock blower motor would be used to blow the cold air.

This has the potential to be totally transparent to the driver. In other words, the driver could be totally ignorant as to how the system works, yet he could still operate it as though it were a standard automotive air conditioning system.

Some manufacturers, like this one make coolers that can cool their contents to as low as zero degrees Fahrenheit (or -18 degrees celsius for those of you who aren't lucky enough to use standard measurements ), so the air coming out of the vents could potentially be VERY cold!

This system would use an extremely small amount of the traction pack's energy. Only the system's small fluid pump and the car's blower motor would be consuming energy. This is in contrast to the design that was linked to earlier in the thread.

Holy Crap! That's a HUGE compressor drive motor. That thing must shorten range considerably! That's not "cool" at all.

Here is one more link to consider for cooling your car with ice.
http://www.kooleraire.com/index.htm

 

[Mastiff]

I like that idea too. It's almost summer here and I'm keen to try and make one myself out of foil-lined flexi-pipe and a big chilly-bin. The next EV will definitely have proper air conditioning for those 2 or 3 months of the year that it can be uncomfortable to be sitting in traffic with your back adhering to the seat.

I also just thought of something to make it even more impressive - buy "dry ice". Dry ice is simply frozen carbon dioxide. It's cheap to buy, stays cool a long time in a chilly bin and is something like -70° C (-94° F) when frozen. A bag of it would last a few days in a chest at home, and you just pour some into your portable cooler when you're heading out. It evaporates leaving no moisture too so there's no water to remove!
I like it! I think I'll try that this summer!

Gavin I'd recommend against leaving Dry Ice evaporating in a closed environment, that's a quick way to get dead.

I'd do like someone else suggested and keep the Dry ice outside the passenger compartment and use a heat exchanger, that would be safer.

If you did use that system, I think you'd also have the only Pure Electric Vehicle that also emits Carbon Dioxide.

I'm not sure how much power it takes to run an A/C compressor but I think the simplest way is to power the A/C off of a small Permanent Magnet motor for maximum efficiency.

Maybe a small 1/4 or 1/2 Horsepower Permanent magnet motor, probably a 12 volt.