Classic Retrofit AC in a 1965-68 911?

[Fleming]

Has anyone done this type of install? Would like to see what was necessary to get this AC into an early car.

Did you use any 1980"s body grafts to make it work. Did you have to make custom fittings? What did you do to the dash? What wiring mods were required beside the upgraded Generator and battery wires?

If you have thought about doing this let us know, this seems like a very good but complicated project.

Thanks.

[FA-18C]

There are some long threads, I think the main challenge will be your alternator. CR may have an alternative for you.

[mepstein]

I’m planning on doing one on my 67. When I asked Johnny he referred me to a couple pics on his website but other than that, there was no info on how to fit it up. It’s a bit more custom than LWB cars since SWB lacks the blower fan in the cowl so the electric unit has to be custom fit.

[mysocal911]

Originally Posted by FA-18C

There are some long threads, I think the main challenge will be your alternator. CR may have an alternative for you.

Always good to do some basic calculations:

1. Typical A/C compressor power demand - 4 hp = 3,000 watts




2. Typical battery/alternator current; 3,000 / 12 = 250 amps, which results in R* I^2 losses in the wiring most don't consider.
The alternator's current output at near idle RPM needs to support over 100-150 amps for acceptable A/C performance, e.g. @ traffic light.

Converting to a DC compressor @ 12V laughable!

[Nditiz1]

Originally Posted by mysocal911

Always good to do some basic calculations:

1. Typical A/C compressor power demand - 4 hp = 3,000 watts




2. Typical battery/alternator current; 3,000 / 12 = 250 amps, which results in R* I^2 losses in the wiring most don't consider.
The alternator's current output at near idle RPM needs to support over 100-150 amps for acceptable A/C performance, e.g. @ traffic light.

Converting to a DC compressor @ 12V laughable!

And yet it still blows cold air in my porsche. Weird huh? Must be some kind of dark magic happening in there.

[mepstein]

Originally Posted by mysocal911

Always good to do some basic calculations:

1. Typical A/C compressor power demand - 4 hp = 3,000 watts




2. Typical battery/alternator current; 3,000 / 12 = 250 amps, which results in R* I^2 losses in the wiring most don't consider.
The alternator's current output at near idle RPM needs to support over 100-150 amps for acceptable A/C performance, e.g. @ traffic light.

Converting to a DC compressor @ 12V laughable!

[RSTarga]

This looks like a good option for less than 3k
https://www.classicautoair.com/shop/complete-ac-systems/1973-porsche-911-non-turbo-lhd-air-conditioning-system/

Add an 85amp valeo

[mysocal911]

Originally Posted by mepstein

The key alternator parameter for an electric A/C system is the current output at idle, i.e. 1000 RPM.
It's not the maximum current output rating at 3,000 RPM.
Remember, the problematic A/C mode in hot weather is stop & go city driving, and not cruising at 70 MPH.

Sorry to find that many don't understand the basics of an automotive A/C system, especially an electric system.
When these guys convert the 911s to an electric motor running at 360 volts, then an electric A/C becomes practical.

[Nditiz1]

Dave, do you actually have a CR kit installed?

[mepstein]

I used to work at a shop that installed at least a half dozen of these kits. Customers were happy with them and that’s why I plan to put one in my 67. I don’t know the math or science behind the system. I just know it blows out cold air in the summer so that works for me.

[Jonny H]

Originally Posted by Fleming

Has anyone done this type of install? Would like to see what was necessary to get this AC into an early car.

Did you use any 1980"s body grafts to make it work. Did you have to make custom fittings? What did you do to the dash? What wiring mods were required beside the upgraded Generator and battery wires?

If you have thought about doing this let us know, this seems like a very good but complicated project.

Thanks.

The blower will fit in the space on a SWB but you will need to remove the cowl stay bar and the rain tray. The underside of the cowl air inlet panel is also different so the blower will not fit straight to it - will need something made up.

There are no holes into the cabin from the 'frunk' on a SWB. You are going to need at least 4 x 60mm holes in the bulkhead - two for outlets and two for inlets. I would also run a face vent in the clock since you have no dash vents on a SWB.

Since the SWB has a single battery and no front oil cooler, dual condensers up front should be relatively straightforward to install.

Electrically, you will need a 3 speed fan switch. We have 175A Alternators for the early engine as already posted.

[Jonny H]

Originally Posted by mysocal911

Always good to do some basic calculations:

1. Typical A/C compressor power demand - 4 hp = 3,000 watts

2. Typical battery/alternator current; 3,000 / 12 = 250 amps, which results in R* I^2 losses in the wiring most don't consider.
The alternator's current output at near idle RPM needs to support over 100-150 amps for acceptable A/C performance, e.g. @ traffic light.

Converting to a DC compressor @ 12V laughable!

'Typical' numbers are just that.

You agree that high voltage electric AC compressors work in electric vehicles, yes?

The Toyota Prius uses a 20cc compressor. It uses between 1000 and 1500W of input power and delivers between 2000 and 3kW of cooling depending on where you set the dial.

We are using an 18cc compressor which we usually run with an input current of 75A, giving an input power of around 1000W and a cooling capacity of 2600W. So, we are not far off the Prius but the 911 has a much smaller cabin.

[tsuter]

Originally Posted by Jonny H

'Typical' numbers are just that.

You agree that high voltage electric AC compressors work in electric vehicles, yes?

The Toyota Prius uses a 20cc compressor. It uses between 1000 and 1500W of input power and delivers between 2000 and 3kW of cooling depending on where you set the dial.

We are using an 18cc compressor which we usually run with an input current of 75A, giving an input power of around 1000W and a cooling capacity of 2600W. So, we are not far off the Prius but the 911 has a much smaller cabin.

Duuuudde.....stop!. You do know that since 2011 at least, the Toyota Prius Gen III uses a 201V battery pack and a 12V inverter converter. The Prius provides 201V to the AC Denso 200V Compressor and with temperature controlled RPM that compressor at a max of 7500RPM will use around 3.4kW and draw 17 Amps! No one is running 12V AC compressors except as auxiliary units for beer coolers, on idle cooling cabs....if they are...post it up...

You guys need to have a signature block that says... :I sell product".....

[tsuter]

Now I only happen to have a Prius 2006 Repair Manual handy, but even in 2006 they were using a 200V A/C Compressor.

[tsuter]

Now why won't a 12V electric compressor work? And why does no one use it as the primary compressor in an auto?

Because in simplest terms it cannot produce the PSI necessary to convert the high pressure R134a gas to liquid at high ambient temps across a condenser(s)
See pic.

Blue is where the 12V compressor will "work". In red ...it will not "work"
For high ambients you must produce 300psi. A 12V compressor cannot do this without a Amp draw so high you will burn up your car.

Now in the red zone, your 12V compressor will run, but you will see 55-65F at the vents.
In the mid zone...maybe you will get 50F at the vents.
Only in the blue zone will your 12V compressor get "cold"

Take your pressures and post a pic. The pressures do not lie.

And maybe this blue zone and 225psi is all you need? Maybe so. Depends where you live.


But if you want cold air at high ambients, then run this system with a nice modern Sanden or equivalent and belt drive. Not a 12V compressor. Or look at one of my other post for how to run a 24V compressor and double your cooling capacity! It may still not be enough, but it will be better.

The modern rotary belt drive compressor on 911 AC retrofits has never been the critical path.

The critical path is in the other components. But it is not the compressor.

[Nditiz1]

@tsuter - ima just leave this here for you

https://youtu.be/hzE5UauN8uQ

But what you don't understand is that even modern cars are not blowing 32 out the vents. Also, who cars about what the temp out of the vent is honestly. The ONLY reason I have this hooked up to my vent is for test runs. Once I'm done, that little temp gauge is gone. I only care about am I getting cool or not. As I have said in my other thread my s10 with a 2003 modern system does not blow ice cubes, but blows cold air with force. In 100 weather I am eventually turning it down after maybe 20 mins of driving AND that is 20 year old tech. Today's cars are probably more efficient. The VWs of that Era were terrible at cooling on hot days, I know because I have a 2004 r32 black on black that seems like the cabin never gets cold. Holy S it's got 30 years on these Pcars yet the AC sucks off a compressor how is that possible. Because the system was poorly designed even off a belt driven compressor.

So stop with all the pressures and hvac jargon, who cares about vent temps. It's all about whether it cools you down or not. Anything under 55 blasting with force will make you feel cool and cool down a heat soaked cabin.

[Jonny H]

tsuter, we design and build HVAC systems from 12V right up to 750V for EVs so I don't need the lecture. Right now, we are designing a system which will do thermal management for battery packs as well as cabin for a major OEM.

The Prius compressor I referred to is a high voltage one as you point out, but there is no fundamental difference to the mechanical design whatever the voltage. It's a rotating machine with a displacement - that's all. I was just stating that the 12V units we use are 18cc / 2600W and the Prius ESB20 is 20cc / 3000W.

Interestingly, your manual from 2006 shows ES18 which is 18cc - the same displacement as the 12v unit.

As you rightly point out, the other components chosen are also critical to operation of an AC. We are a Denso 'specialist' (their words) so we only use OEM heat exchangers which have the latest evaporator core technology (which has only been around for a few years). These are matched to the electric compressors so that the system is as efficient as can be. There are no aftermarket AC blower units that have this technology - it is heavily protected by the OEMs.

Every AC system has its limit of operation but by using the correct combination of components, efficiency can be maximised. On the plus side, the 911 has a small cabin which results in acceptable performance in climates up to 40 deg C.

Regarding your pressure chart, electric compressors run far less pressure. If you look in your Prius manual, the normal running PSI is stated as 1.37 to 1.57 MPa (199 to 228 psi)

Our last designed 12V system is fitted to the McLaren Solus GT. If you looked at the size of the components, based on 'conventional' AC thinking you would say it couldn't work - condenser is just 14 x 5 inches, placed in the side skirt (there is no frontal area on the vehicle as it open like an F1 car). Again, small cockpit and driver targeted vent system. It works great.

p.s. I didn't come on here to 'sell product'. I came to help out the guy with the SWB. But as usual, the trolls come out and start having a pop with supposed 'facts'. Sorry if having to correct that is viewed as 'selling'.

[Jonny H]

Originally Posted by Nditiz1

https://youtu.be/hzE5UauN8uQ

Looks pretty cool to me.

[tsuter]

Originally Posted by Jonny H

Looks pretty cool to me.

Dude!!! Just give it a break! His ambient is 85F! His garage is 75F! That is in the "blue" zone as I posted above. And from all his posts he is happy with 50s with fan on high.

But he won't show us the pressures will he??

That is great (maybe) for a portion of the population.

But not where I live....

My garage is 96F and ambients today are 104F. That 12V compressor cannot deliver the PSI to condense the R134a. And it never will in these temperature zones.

You and he are misrepresenting the EV technology and doing it intentionally to push sales.

He and you would get much better results with a Sanden Belt drive rotary instead of the 12V compressor and still using all your other technology. There would be no comparison at high ambients because the Sanden can deliver 325psi plus.

There is no reason in these cars to use a 12V compressor. The compressor was never the critical path of the 911 once updated to modern Sanden type rotary.

If you guys have all this design expertise, then design a 24V system and double the cooling capacity! I already told you how.... And did not even require and NDA.

[Jonny H]

Give what a break - defending our products against misleading posts? Not gonna happen.

For the record Nick (Nditiz1) is our customer. He is not paid and did not receive any free goods so please do not imply he is anything to do with us.

I did not come here to 'push sales' - I posted to defend our products against misleading information that is derogatory.

You are posting pictures of pressure charts that are aimed at clutch based mechanical systems. You are implying that pressure is the definitive 'proof' that our system can't work.

Yes, our pressures will be low compared to a mechanical system (between 160 and 220 PSI). Operating pressure is typically maxed at 220 PSI even for a high voltage EV compressor. The guy in this video at 8.15 is running a Prius system in 90F and shows a pressure of just over 200 PSI. Now, according to your chart, a Prius A/C can't work above 80F!

https://www.youtube.com/watch?v=cFy_570ecKM

Originally Posted by tsuter

.
There is no reason in these cars to use a 12V compressor.

Many reasons:

Reduce weight ( less than half the weight of the original )
Move weight to the front
Shorten the hose length
Less HP used
Non-Invasive - no mods to car/engine required.
Easier to install.
Engine compressor sure looks looks ugly.