# Air Conditioning... Again



## TelnetManta (Jun 5, 2008)

I've read most of the posts here on this subject and still have a few questions. I thought it might be good to start a new thread as I plan/MUST have A/C in my conversion. I'm planning to use a motor to turn the A/C compressor and while I'm at it the power steering pump. 

What I wondered is if I use a smallish 1HP DC motor such as one from a treadmill should I power it directly from pack voltage? If so do I need to worry about anything other than a good relay/contactor to control it? If the electric side is that simple then I can begin to worry about the mechanical side.

Thanks,
Ben


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## judebert (Apr 16, 2008)

I did exactly this, connecting a 1.5HP treadmill motor (120VAC, universal motor) directly to my 144V pack. It went crazy; through the holes in the motor you could see it glowing orange as it spun.

I'm thinking a little controller would be a good idea. I'm in Florida; I *need* A/C for some portion of the year. (Okay, I'm currently doing without; I don't need it, but I would really, really, REALLY like to drive without sweating to death.)


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## TelnetManta (Jun 5, 2008)

We have heat like Fla, maybe a little cooler, but we have crazy humidity. I guess a PM motor would work better but they are HUGE!

Anyone else have experience OTHER than the swamp cooler ideas? Even with the known losses, range etc, I would like to talk about options for connecting a small electric motor to run the accessories.

Thanks!
Ben


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## Jeremy (Jul 12, 2008)

One option might be to look for a late model (NHW20) Toyota Prius AC unit, as it's a sealed electric system already.

I've no idea whether these are readily obtainable from wreckers, or how easy they are to drive, but I'm guessing that it must be do-able as the Prius runs it's AC compressor off the battery.

Jeremy


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## etischer (Jun 16, 2008)

I bought a 1hp AC motor for around $40, and a 2hp AC VFD drive for around $40. Ebay is great! I'm hoping to direct drive my AC compressor and eliminate the clutch and belt. I was going to use the signal which runs the clutch as an input to my drive to start the compressor. 

I also bought a 2hp AC motor, so I may use this for the AC and the 1hp for power steering and a water pump.


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## stormcrow (May 28, 2008)

Another option is using the treadmill electric motor and getting one of those outlet converters you can buy for your car that plugs into the cigarette lighter. Those take the 12vdc from the car and convert it to your standard 120vac current in your house. You could probably pick one of those up, take it apart, and hard wire it into your car for your treadmill motor to run off of. And it would just pull current from your 12v battery instead of your high voltage pack. The only downside I can see is that you might have to add an extra 12V battery if you are going to keep the motor running all the time. Just a thought.


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## TX_Dj (Jul 25, 2008)

I've always felt that I would disable my power steering when I get to that point, but at the same time I really like having power steering when parking... but power steering is more or less useless at high speeds, because it will turn fine so long as you're in motion.

Also, being in the middle of a heat wave here in TX, it'll be a cold day in you know where before I call an EV conversion "complete" without cold AC.

As such, this is what I've been thinking-

1) AC - Either get an all-in-one unit such as (presumably) the prius uses, or similar to that used in a window-unit home AC. Rig it on a contactor that is controlled by the AC system in the cab. Failing that, a small motor of sufficient power to drive the vehicle's stock AC compressor, again with the contactor that will switch the motor on and off per the request of the in-cab AC system controls. Dedicated motor, and the AC compressor clutch assembly would be removed in favor for a solid pulley (for reliability reasons, and simplicity).

2) PS - I'd either want an electric hydraulic pump (a 12v pump probably has enough guts to do it) or something to drive the stock vehicle pump... but in either way, I'd wire it to a relay or contactor that I can switch on and off manually in the cab (near the wheel for easy reach) so I can switch it on when I really need it, and save the power for when it's not necessary. However, I'll probably just bypass the power steering altogether. I've driven several vehicles in this size/weight without PS, and survived...


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## TelnetManta (Jun 5, 2008)

So I've been looking for either a 1-2hp motor that can run at pack voltage of 144V or a motor that can run at 12V can still provide 1-2hp. Either way it's been tough, haven't found a whole lot yet.


The Prius compressor is pretty expensive even if you can find one. Then adaptingit would be even harder in my car because of the different refrigerant.



Ben


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## TelnetManta (Jun 5, 2008)

My cars a BMW so it just wouldn't feel right without AC and PS


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## ngrimm (Oct 19, 2007)

Do any of the rvs or motor homes use 12 volt dc air conditioning or or are they all ac with an inverter?


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## TX_Dj (Jul 25, 2008)

All AC. Though it could stand to reason that if you were so inclined, you could make a heating element type compressor for the car, and have even fewer moving parts, similar to how an RV refrigerator works.

Manta- Really doesn't matter if you're using freon or R134a, to do the conversion, all that changes (if I recall correctly) are the H/L side valves, the orifice tube, and a complete flush of the system to get any incompatible lubricants out of the system. If you're going to do anything on your EV's AC, I'd really recommend looking into converting to R134a for both the environmental benefit and reduced cost of maintenance. (I.E. not all shops handle freon anymore, because it's required to have a vacuum reclamation device to prevent it from going to the atmosphere, and all the freon-capable shops have to have a costly license... not to mention freon is incredible expensive these days and you can buy R134A at any parts store)


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## Qer (May 7, 2008)

TX_Dj said:


> All AC. Though it could stand to reason that if you were so inclined, you could make a heating element type compressor for the car, and have even fewer moving parts, similar to how an RV refrigerator works.
> 
> Manta- Really doesn't matter if you're using freon or R134a, to do the conversion, all that changes (if I recall correctly) are the H/L side valves, the orifice tube, and a complete flush of the system to get any incompatible lubricants out of the system. If you're going to do anything on your EV's AC, I'd really recommend looking into converting to R134a for both the environmental benefit and reduced cost of maintenance. (I.E. not all shops handle freon anymore, because it's required to have a vacuum reclamation device to prevent it from going to the atmosphere, and all the freon-capable shops have to have a costly license... not to mention freon is incredible expensive these days and you can buy R134A at any parts store)


You lucky bastards. Over here R12 is dead since years ago (you're not even allowed to refill a R12-system) and R134A can only be handled by qualified staff. Buying R134A yourself is not even on the scale, unless you know someone with connections.

Personally I'm thinking of going carbon dioxide or possibly LPG if I start tinkering with AC myself since I've heard success stories with both approaches. Only problem, since it's illegal to tinker with AC yourself (due to the freon regulations) there's of course no tools you can buy. Perhaps I can bribe a swede I know that has emigrated to the states but still comes home to visit his parents from time to time to bring me the stuff...


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## TX_Dj (Jul 25, 2008)

And over here, LPG in your AC in a vehicle is strictly against federal DOT regulations. Something about having a flammable liquid moving through pipes. Hmm. I love the irony of their double-standards. Actually I think it has to do with the fact that in some cars the AC parts enter the cab, and an LPG leak could cause a serious hazard, either by displacing air or by killing smokers. 

I would be interested in doing CO2 as a refrigerant, but I don't know if it's potent enough to handle days like today, 105F (40-41C) @ 50+% humidity. 

Some cars w/ R134A have a hard enough time keeping up with that kind of weather.


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## Qer (May 7, 2008)

TX_Dj said:


> And over here, LPG in your AC in a vehicle is strictly against federal DOT regulations. Something about having a flammable liquid moving through pipes. Hmm. I love the irony of their double-standards. Actually I think it has to do with the fact that in some cars the AC parts enter the cab, and an LPG leak could cause a serious hazard, either by displacing air or by killing smokers.
> 
> I would be interested in doing CO2 as a refrigerant, but I don't know if it's potent enough to handle days like today, 105F (40-41C) @ 50+% humidity.
> 
> Some cars w/ R134A have a hard enough time keeping up with that kind of weather.


Well, if I try LPG I sure as hell won't tell anyone! 

I don't worry much about LPG as a fire damage or so since the amount you need for an AC isn't that much + that as long as it's 100% concentrated it doesn't burn (no oxygen). Of course, the real problem is when it starts to leak, not the gas that leaks out but the gas/oxygen mix you'll end up with in the pipes that will eventually turn very dangerous.

R600, which they've started to use in newer cars, is n-butane, whatever that is. I wonder if it's flammable...?

But yeah, I'd prefer using CO2. Sounds a lot safer...


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## DVR (Apr 10, 2008)

Has anyone seen any hard evidence as to what is the smallest amount of power required to run a P/S pump and a A/C? I know that the MR2 P/S pump can pull 60 amp when under load what does that equate to as far as HP?


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## Qer (May 7, 2008)

DVR said:


> Has anyone seen any hard evidence as to what is the smallest amount of power required to run a P/S pump and a A/C? I know that the MR2 P/S pump can pull 60 amp when under load what does that equate to as far as HP?


Some guy in the forum (sorry, don't remember who) said it took about 400 Watt to run the AC in his car. 60 Amps multiplied with 12 Volt (that's the right Voltage?) equals 720 Watt. One horse power is 735-736 Watt so that's a pony for the AC versus a galloper for the PS.


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## DVR (Apr 10, 2008)

So then would a motor like this be suitable?
http://cgi.ebay.com.au/Treadmill-Re...NameZWD2VQQcmdZViewItemQQ_trksidZp1638Q2em122
What exactly is "treadmill duty"?


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## TelnetManta (Jun 5, 2008)

The only problem I see the the RPM at pack voltage.


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## Vwbeamer (Jun 16, 2008)

Because 99% of the cars on the road don't have flamable liquids under pressure under the hood now, right?



Qer said:


> Well, if I try LPG I sure as hell won't tell anyone!
> 
> I don't worry much about LPG as a fire damage or so since the amount you need for an AC isn't that much + that as long as it's 100% concentrated it doesn't burn (no oxygen). Of course, the real problem is when it starts to leak, not the gas that leaks out but the gas/oxygen mix you'll end up with in the pipes that will eventually turn very dangerous.
> 
> ...


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## Qer (May 7, 2008)

DVR said:


> So then would a motor like this be suitable?
> http://cgi.ebay.com.au/Treadmill-Re...NameZWD2VQQcmdZViewItemQQ_trksidZp1638Q2em122
> What exactly is "treadmill duty"?


Well, as far as I can tell it should be just dandy. If the compressor works so hard it keeps turning on and off you can always PWM it down a bit in speed. That might save you some energy, possibly (or it will not ).

Hmm. You might have a problem with if the compressor disengage the coupling btw, the motor will probably run wild so the same circuit that turns on and off the compressor coupling should probably turn off the motor too.


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