I have just finished installing an AC system with an electric 12V AC compressor with an "odd" collection of condensers which to my happy surprise appears to be working well or at least well enough! I committed to this some four or so weeks ago after much input from Steve, who has done most of the research, and had already bought most of his parts and tools to install a similar system to mine. He kindly lent me the tool to crimp the hose attachments, and the tools to charge the refrigerant into the system.

I purchased: 1) a new Benling 12V electric compressor from Steve, 2) a new Mini- cooler AC only evaporator from Southern Rods, 3) four used radiators/condensers (two 911 front condensers, and two early 2000’s Ford Explorer auto transmission oil cooler radiators from a wrecking yard (“El Cheepo”), 4) a new drier, also from Southern Rods, and 5) most of the Reduced Barrier hoses and fittings from Air Parts and some from Mesa Hose.

The pics show the compressor installed in the frunk behind my oil cooler shroud, the evaporator under the glove box, two 911 condensers “sandwiched” together with my Mazda engine oil cooler – all threes under the same slightly modified cowling with the 12” fan pulling/pushing the heated air through the bottom of the frunk, and a poor picture showing one of the modified Ford radiators (now AC condenser) with a 7” fan located in front of the passenger side rear wheel – the other similarly located in front of the driver side rear wheel. The drier is attached to the driver side frunk wall. I had the Ford 10”x7” radiator hose fittings modified to fit AC O ring seal hose fittings.

Other than simple challenges to fabricate the mountings for the compressor and the evaporator, the space and angles of available surfaces to attach the two condensers in the wheel wells were challenging but doable after much trial and error and adjustments to the aluminum brackets I fabricated.

The hose sizes and fittings were a challenge. The normal #10 and #8 hose fittings to the compressor are too bulky for my application, but Classic Retrofit came to the rescue supplying their efficient/elegant compressor/hose fittings. I learned that the modern Reduced (outside dimensions) Barrier (required to contain R134a refrigerant) hoses are more flexible, and need less space.

With the system running now, I measured the amps being generated by the alternator and the amps being absorbed by the compressor, all with a fully charged battery. The compressor is pulling 40 amps, and the alternator is generating 40 amps at 900 rpm engine idle speed, but 70 amps at 2000 and above RPM. I have a Denso 175 amp alternator on order, which should arrive tomorrow!
So we will see how all this performs later this week.

My grandson’s 3D printing skills produced three 45 degrees slip-on cold air “direction adjustment tubes” which is a nice finish for this application (see pics)!

The road test today was short but encouraging. I am joining the caravan from S. Cal Wed. morning to the Red Rocks Classic 2020, and expect to give this system a serious test through the desert!!

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Nice Keith, can't wait to see how it works on your trip.

Be Safe...



Oscar

Nice work. Please update us on this after your drive. Very interested in your thoughts.

Safe travels!

I’m very interested in a AC setup as well looks good.

Nice install, looking forward to a progress report.

Nice setup, and being electric definitely has the advantage of letting you put the compressor wherever is convenient.

Curious on the use of 4 condensers vs 1 - was that because of the space you had available or another reason? Also hadn’t thought of if before but interesting that those are good for the pressures in the system also.

Stay cool

Very cool Keith

Strong work......

Great idea - I saw this on the episode of Vintage Voltage but they never aired part 2 due to the Vid. Curious why so many condensers too?

After I had bought the two 911 front condensers and had mounted them in front of my oil cooler, various “experts” suggested that they were not enough and less efficient then the new aluminum condensers, especially after Jonny pointed out that two together sharing the same air are only 10 to 15% better than one with the same air. This coupled with the already in place very effective Mazda oil cooler left me with little alternative than the space in front of the rear wheels for mounting additional condensing with fans.
If I was starting on a clean slate, I would design a frunk cowling to accommodate an oil cooler and an AC condenser that are angled so as to accommodate a wider AC condenser of modern design, say approx. 24” wide by 15” or so. That should be enough for our small volume cabins.

Nice ....

What a great installation The adaption to electric is a breakthrough for the 914s
Have a great trip to Durango...

Hey keith .i new you were crazy when you sold me that engine ( still running strong )btw.

But wow. Thats some ac setup .
Vanity plates should read ..... Meat locker

It will be fine going there. They are forecasting some hot Wx on our return trip. Congrats and cheers.

Get a cheap digital / cooking thermometer before the trip. A good system will see a 40F drop between ambient and output temps. Some of the newer cars I'm seeing a 50F drop.

Being such a small cabin and recirculating even if it sucks it will still cool good enough.

Are the condensers plumbed series or parallel?

In series, out the bottom and in the top of the next one.

Impressed by results ,though there would be a higher power consumption ?

[quote name='914Toy' date='Sep 7 2020, 03:50 PM' post='2849294']
I have just finished installing an AC system with an electric 12V AC compressor with an "odd" collection of condensers which to my happy surprise appears to be working well or at least well enough! I committed to this some four or so weeks ago after much input from Steve, who has done most of the research, and had already bought most of his parts and tools to install a similar system to mine. He kindly lent me the tool to crimp the hose attachments, and the tools to charge the refrigerant into the system.

I purchased: 1) a new Benling 12V electric compressor from Steve, 2) a new Mini- cooler AC only evaporator from Southern Rods, 3) four used radiators/condensers (two 911 front condensers, and two early 2000’s Ford Explorer auto transmission oil cooler radiators from a wrecking yard (“El Cheepo”), 4) a new drier, also from Southern Rods, and 5) most of the Reduced Barrier hoses and fittings from Air Parts and some from Mesa Hose.

The pics show the compressor installed in the frunk behind my oil cooler shroud, the evaporator under the glove box, two 911 condensers “sandwiched” together with my Mazda engine oil cooler – all threes under the same slightly modified cowling with the 12” fan pulling/pushing the heated air through the bottom of the frunk, and a poor picture showing one of the modified Ford radiators (now AC condenser) with a 7” fan located in front of the passenger side rear wheel – the other similarly located in front of the driver side rear wheel. The drier is attached to the driver side frunk wall. I had the Ford 10”x7” radiator hose fittings modified to fit AC O ring seal hose fittings.

Other than simple challenges to fabricate the mountings for the compressor and the evaporator, the space and angles of available surfaces to attach the two condensers in the wheel wells were challenging but doable after much trial and error and adjustments to the aluminum brackets I fabricated.

The hose sizes and fittings were a challenge. The normal #10 and #8 hose fittings to the compressor are too bulky for my application, but Classic Retrofit came to the rescue supplying their efficient/elegant compressor/hose fittings. I learned that the modern Reduced (outside dimensions) Barrier (required to contain R134a refrigerant) hoses are more flexible, and need less space.

With the system running now, I measured the amps being generated by the alternator and the amps being absorbed by the compressor, all with a fully charged battery. The compressor is pulling 40 amps, and the alternator is generating 40 amps at 900 rpm engine idle speed, but 70 amps at 2000 and above RPM. I have a Denso 175 amp alternator on order, which should arrive tomorrow!
So we will see how all this performs later this week.

My grandson’s 3D printing skills produced three 45 degrees slip-on cold air “direction adjustment tubes” which is a nice finish for this application (see pics)!

The road test today was short but encouraging. I am joining the caravan from S. Cal Wed. morning to the Red Rocks Classic 2020, and expect to give this system a serious test through the desert!!















Nice Work Keith!

Nice talking to you about the alternator, and have fun on your trip!

Joe Foster is new to our community. Long time Porsche Phile and he has a bunch of parts. I've bought from him and he is, well he is a good Joe. Sorry, I couldn't help myself. He is in Fontana. 775-771-3190

Keith, fasinating AC project and engineered like everything on your car. Looking forward to seeing it at Crystal Cove sometime-Have a fun trip to Red Rocks

I too am considering using an electric AC compressor when I add Ac to my car. Which model of Benling compressor did you use?

I found an interesting old book entitled "How to Air Condition Your Car" written in 1993 by Timothy Remus and Jack Chisenhall, and published by Motorbooks International. It advised that the condenser used should be 25% larger than the evaporator in capacity. From your post, am I understanding it correctly that you used two Porsche 911 condensers, as well as a Ford 10"x7" radiator repurposed into a third condenser?

Where did you get the Denso 175 amp alternator? And is it a direct replacement for stock?

Benling DM18A7
https://benling.coowor.com/shop/product-det...09087VFAMP1.htm

I used two 911 front condensers (one 911 SC (pressure hose fitting) and one Carrera series (O ring fittings)) sandwiched together directly in front of a Mazda oil cooler, and two (one in front of the passenger rare wheel and the other in front of the driver side rear wheel) Ford 10"X7" transmission oil coolers with AC modified hose connections, each with a 7" fan placed directly on the modified condensers. I was advised, after purchasing and installing the 911 condensers, that two identical condensers sharing the same cooling air passthrough would only increase their cooling capacity by about 15%, not 100%!

That's why radiators are only 1" thick on new cars these days. The temperature differential is negligible after that. Your oil cooler is hardly cooling anymore.

How did the long test drive go?

I was expecting a 170 amp alternator to arrive in time to be installed before Red Rocks, but it arrived a day too late. Given the possibility of overheating the existing alternator and burning it up, including a possible fire, I chose not to test it further than the 20 minute successful test I did before leaving. I will be installing the new alternator this week and will be reporting back.

Jury is in: The compressor has three choices of rpm speed.

1) On low compressor speed with ambient temperature of 86F, the evaporator exiting air was down to 60F, so delta of 26 degrees. The new 170amp alternator was generating 66 amps at engine idle, and at + 2000rpm was still generating 66 amps. The compressor was pulling 44 amps at any engine speed.

2) On medium compressor speed with ambient temperature of 88F, the evaporator exiting air was down to 57F, so a delta of 31 degrees the amps from the alternator and amps into the compressor did not change much from above setting.

Full disclosure: temperature measurements were with a new digital meat cooking thermometer. Not easy to measure/record numbers by myself in the car, but these numbers are close averages. Will check again with an assistant.

So far so good!

BRAVO Keith!! !Hats off to you Sir.
I was thinking of doing this set up as well. One of the reasons I wanted to go electric ac was to not draw power from the engine when the compressor kicks on. On newer cars the ECU would bump up idle speed to make up for the load of ac compressor operation. Do you notice any difference in idle speed when your ac kicks in? I wondering if electrical load would change your idle speed?
I also see you have it hard mounted to the car. Can you feel when the compressor when it is operating?

AL

The alternator is generating power to feed the compressor, and although the compressor is not mechanically connected to the engine, the energy required to turn the alternator is obviously coming from the engine, thus slows it down very slightly at idle, and reduces HP to the driving wheels. But I cannot feel any difference in engine power when accelerating.

The compressor is mounted on four rubber “thingies” that insulate sound and any vibration.

I was thinking about your AC today. Hang the numbers. Drive it around town this afternoon and if your comfortable then you are good to go. Cheers

You are right, and I did drive it for an hour pr so. That cool air blast from the cabin mourned evaporator is pure luxury

That is awesome news!!! Can’t wait to get mine working!!

Great job Keith. Let me know when you want to sell and start in on something else?

The ac is impressive
But im not to surprised . watching you build those carbs was more impressive.

Youre old engines still running like a freight train no speeding ticket s yet ..


U the man

Thanks for your comment.

Luxurious it is but more importantly the heat doesn't rob you of your energy. The AC makes a world of difference on long drives. Enjoy the Hell out of it Keith.

I’m speechless.

When we announced our electric AC kit for 911s on Pelican 4 years ago, this started a 45 page ‘naysayer’ fest. That was despite climate chamber testing at 110F, a comprehensive published test report and two years of real world testing.

A 914 guy gets 57F at the vent on a warmish day and he’s a hero. You sure are a nicer bunch!

The key to getting these compressors to work at maximum efficiency is in the speed/power management. And if you were wondering, that’s what the software in our ECU does.

The following video was filmed at 34C / 93F with blower fan on full. 3C / 37F at the vent in less than 5 minutes.

https://youtu.be/735lNeSgfGs

Can anyone tell me where to get these AC compressors? Ive been searching the web and found some in china but need to buy in bulk and not sure to trust foreign seller because of risk of getting ripped off. Does anybody have a trusted vendor anywhere that can supply these compressors? What is the best price for one of these compressors?

I'm looking forward to installing your kit in my 930. Black interior with black exterior is quite hot in the summer. I'm tired of driving to/from work in the 930 and arriving in a total sweat.

Steve will probably respond to your request for sourcing the compressors.

My next step is to put some heat reflective film on the windows.

The Benling DM18A7 shows up on eBay for around $799.00
https://www.ebay.com/itm/202916972654
This is the model that we used.
Click to view attachment

What kind of a controller are you using to control the speed of the electric AC compressor?

The compressor has three rpm speeds one can select by connecting one of three wires (orange, green, and white, need to check colors:wacko:) to the evaporator signal wire. Or a three way switch is available to select speeds "on the run". I did not want one more controller, so tried the slowest wire connection and then settled on the second one after considering amp draw by the compressor and generation from the alternator. Not optimum or sophisticated but adequate for my purposes.

Thanks for answering my question. I was thinking of using an electric AC compressor because I did not want to be cutting up the engine compartment and cooling tins. You have persuaded me to do so!

I am jealous of a 914 with a 170 amp alternator. Why is it only producing 66amps of power though? I'd think at 2000 RPM you would be making more power.

Did you notice any issues running all the other stuff with only 22amps remaining power? Did you do any tests like turning on the headlights, wipers etc and seeing how everything held up power wise?

I know there was a guy making 140 amp alternators for TIV motors some time ago, and Joe Sayre was running one of them to power his HID lights and big stereo/amp/second battery setup. I wonder if they still exist.

Zach

My red car as a stock 180A alternator. But it was for a 964 with lots of power accessories.

So Electric AC is in my future.

Clay

66 amps might be the total load, the alternator should only be producing the required load. I don't think many have a charging system load tester around the house.

For a 911 engine, do not trust any alternator ‘rewind’ that claims more power in a standard casing. The windings can’t take the heat and there is no internal fan in the old casing.

I personally hold the world record for setting fire to rewound alternators in 911 fan housings.

That’s why we designed a unit based on modern internals. You can learn more here:

https://youtu.be/P9dy5wSbeHk

Curious? 964 alternator is 115/40. That’s 115A peak but only 40A at idle.