Porsche A/C Observations over 40 years

[Coastr]

I must say the fuse panels and CDI systems are not cheap so I'm guessing it will be around $4k AUD by the time it gets here.

pure speculation on my part though.

[Stu]

$4k that sounds interesting if it is all it appears to be i.e. Works, not hard to install and no lasting damage. Based on comments above I was expecting engine rebuild prices - keen to see if it lands here!

[Joshstix]

Surely the amount of current draw at 12v to turn a compressor equal to the belt driven compressor would be massive.  Hell I've driven cars where I needed to turn off the A/C for up hill sections of road.

I'd struggle to bring myself to pay big money for an A/C system developed in a market where low 20 degrees C is considered hot.

[Coastr]

Surely the amount of current draw at 12v to turn a compressor equal to the belt driven compressor would be massive.  Hell I've driven cars where I needed to turn off the A/C for up hill sections of road.

I'd struggle to bring myself to pay big money for an A/C system developed in a market where low 20 degrees C is considered hot.

if you read the technical details it has a 40a draw on the alternator.  I doubt it would pull 40a all the time.  It has smarts built in so that it doesn't overtax the electrics somehow.  I would guess a new alternator and voltage regulator is a smart buy at the same time.

they have been doing hot weather testing in the USA (clearly that is the market) and they rented a heat chamber for testing in 45deg heat.   An electric compressor has the possibility of being more efficient than a crank driven compressor because it can run at a constant peak speed.  Car compressors have to deal with 800-8000 rpm.  From reading everything that has been written, it seems the airflow was the biggest area of concern rather than compressor performance.

[clutch-monkey]

I must say the fuse panels and CDI systems are not cheap so I'm guessing it will be around $4k AUD by the time it gets here.

pure speculation on my part though.

making my own system cost that much so save yourself the time and get the CDI system.
will report back how well it works.

my alternator was beefed up at the same time.

Edited 23February, 2017 by clutch-monkey

[SimonN]

Surely the amount of current draw at 12v to turn a compressor equal to the belt driven compressor would be massive.  Hell I've driven cars where I needed to turn off the A/C for up hill sections of road.

12v a/c compressors are now well proven(along with 24v) and are fairly common in trucks and large mechinary. Now mainstream car manufacturers are using them. For the after market, there are a number available and they get great reviews. I actually haven't heard bad things about them. I started investigating this technology 2 years ago and was going to build my own system. I have been looking at the SHM electric compressor which draws 32a, coupled with a Vintage Air Heat, Cool and Defrost Unit in order to get rid of the heat exchangers. This system is pretty well proven for both porsche and VW, but there is still a fair bit of messing about to fit it.Now the above system is nearly ready and seems to be very complete, which will take out a lot of hassle, I am going to wait and see how much it is. The only downside for me is that it still relies on the heat exchangers.

 

[Joshstix]

So even if it drew 40A constantly at 12v that is only 480 watts.  Would you buy an A/C unit with so little power for even a single room in your house that has about 10% of the window area to air volume that your car has?

Actually forget about the home A/C comparison, if the advertising for this stated it was a 0.66hp A/C system would you buy it?

I'm not saying its impossible to make a decent DC electric A/C system and yes I'm sure in a modern car where the system has been designed to fit the job it would work satisfactorily.  However modern cars are far better insulated and sealed than an old 911.

[MFX]

Talking to Jonny, you need to have a minimum of a 95A alternator. These came out on the 3.2s. If you have an SC or earlier you will probably have a 75A alternator. Apparently the 75A can run the system, but if you start to add in headlights on windscreen wipers, it can't keep up. 

I looked into what it would take to fit the later 95A alternator, and it doesn't fit in the older fan housing. You either need to machine the housing or get a later one. That whole process is a rather expensive addition on top of the cost of the A/C system. 

I then searched everywhere around the country to see if someone could rebuild my 75A alternator to a 95A output. I had 7 or 8 places saying it was not at all possible. I finally found http://www.rapidpower.com.au/index.htm in Qld who said no problems. They can rewind the stator to whatever output you want for $150+gst. 

[SimonN]

So even if it drew 40A constantly at 12v that is only 480 watts.  Would you buy an A/C unit with so little power for even a single room in your house that has about 10% of the window area to air volume that your car has?

Actually forget about the home A/C comparison, if the advertising for this stated it was a 0.66hp A/C system would you buy it?

I'm not saying its impossible to make a decent DC electric A/C system and yes I'm sure in a modern car where the system has been designed to fit the job it would work satisfactorily.  However modern cars are far better insulated and sealed than an old 911.

It isn't as simple as you are making out and you are not comparing like for like. You are quoting input and comparing that with output. While I have no idea the specification of the compressor that is being used in the kit above, but the one I linked to uses 32a and has an output of 4000 BTU/hr, or 1.2Kw which, if you take a decently efficient system, is about what you would expect for the power input (COP of 3.125). Check this against specs and performance of conventional car systems and it stacks up very well. All things being equal and assuming the same performance, I would expect the 40a model being used in this kit to produce about 5000 BTU/hr, or 1.5Kw. While that might not be enough for old school condensers and evaporators, it should be more than enough for modern efficient ones and as such, those numbers make sense as being able to cool a Porsche. I also know that the 32a compressor is well proven with VW Beetles in very warm parts of the USA, so I would imagine the kit with the 40a compressor is going to lead to a very well cooled car.

This is why car manufacturers are going over to electric compressors for AC systems and most people don't even know that it is happening. It started with trucks and large scale plant. With the trucks, they needed systems that would work when the engine is off. Power requirements are key, because the last thing you want is the truck driver to wake up after a night's sleep and have a flat battery. I know that both VW and Toyota are using these small electric powered compressors, and I can't believe they are the only ones.

[Stu]

Well I might be able to afford/get an air on for the SC. This thread is like Dr Jeckle and Mr Hyde! ?

[clutch-monkey]

as per simon's post i have a renncool truck cab compressor in an E9. i'm still finalising final parts for it but will report back how effective it is considering how big the glasshouse is on an E9

[Peter M]

Interesting: http://www.rencool.com.au/product/ev-2208/

 

[scashin]

This electric AC system sounds interesting.  Just found this link posted 5 days ago 

http://www.ferdinandmagazine.com/porsche-911-electric-air-con

[Stu]

@scashin that sounds amazing! They sound like the have thought of all the issues and have solved them well. I wonder how much it is!?

@buchanon automotive what do what do you think of it?

[scashin]

Like anything new and potentially game changing...

 

 

[SimonN]

This electric AC system sounds interesting.  Just found this link posted 5 days ago 

http://www.ferdinandmagazine.com/porsche-911-electric-air-con

@scashin that sounds amazing! They sound like the have thought of all the issues and have solved them well. I wonder how much it is!?

@buchanon automotive what do what do you think of it?

Guys

Look further up the thread. We have been discussing this very system and you will find links to a lot more information on the previous page I have been following the development for at least a year. No prices yet, but I believe the target is under GBP 2500 or AU$4000

[Buchanan Automotive]

Actually is not game changing at all , its just changing the pump( compressor ) from being mechanically driven by the engine crankshaft pulley( factory design ) to an electric driven pump ( compressor ) & there are some quite potential issues that are not addressed & one of these is too much A/C hose ( again )& the other is excessive amperage consumption

First of all , lets take a 1984 to 1989 ( example only ) 3.2 911 or a 3.3 Turbo , these cars have an excellent quality Nippon Denso compressor as a factory fit ( factory A/C ) and nicely alloy brackets to secure it , remember with the A/C on ,this compressor will not ( in its self ) draw on the very limited amount of "Spare" amperage the 3.2 NA or 3.3 Turbo Alternator can supply at idle & or low speed in traffic ( Sydney / Melb /Brisbane traffic conditions )

Note } The 2.7 , 3.0L , 3.2L, 3.3L ( up to 1989 ) has only ONE very small already taxed fan belt that also has to drive the engine fan , upping the strain on the alternator with extra amperage demand is not ideal

Note 2 ) With the factory ND comp ( 1984 - 1989 ) there is no amperage consumption needed once the compressor is engaged because its mechanically driven = less load on the alternator and battery ( So its not archaic , but sensible and proven to work for decades )

Note 3 } there were only one thing that were quite nice on the factory first A/C system on the 911 NA & 3.3 Turbo 1984 - 1989 & thats the ND compressor & alloy brackets & front 1986 to 1989 there two nice things , first is the ND compressor & the 2nd is the larger dash air vents ( just needed more air flow ), the rest of the factory A/C is basically crap by todays standards , but OK for the 1970's Euro standards in a mild ambient temp country 

But with an aftermarket electric driven A/C compressor this is going to be a significant amperage ( consumption) draw , and remember you will have the evaporator fan running & the condenser fan running & the engine management system + electric fuel pump & headlights & wipers + stereo etc etc , these cars have a very limited alternator capability at idle in traffic = battery amperage discharge ( opposite to battery charging )

So straight away we can see the advantage of the good quality "Factory " 1984 - 1989 911 Japanese made ND compressor & the way its driven by the engine ( no issues here )

So thinking logically in respect to A/C and the heat conditions is Australia and the above model 911 ( 1984 - 1989 )with factory A/C , all it needs is three main design changes 

A )  Short flexible A/C hoses from the A/C compressor ( Thats on the engine ) to fixed to the body alloy A/C tubing ( insulated ) from within the engine bay , reducing the 36 feet of A/C hose to say 3 or 4 feet of hose MAX ( less hose= less A/C gas lost over time )

B  An aftermarket evaporator unit ( like the evaporator unit shown in the Ferdinand Magazine )& naturally air vents from the modern small "ish"evap unit venting to the standard dash vents , naturally the 1986 to 1989 911 will work the best here ( large air vents ), mounted near the existing main demister fan unit in the luggage bay
 

C  )  An aftermarket A/C condenser & fan unit( to shed heat) in the N/S/F guard ( like in the Ferdinand magazine ) which is what Porsche did with the 964 & 993 911 , but to go one step further , have a 2nd ( optional )A/C condenser & fan( to shed more heat ) unit in the N/S/R guard , because the single condenser size is a bit too compromised ( too small ) for high heat conditions in Australian bumper to bumper traffic , having two of these condensers will increase the cooling efficiency a lot  & where possible alloy tubing to connect everything ( minimal A/C hose )

A lot of re-engineering & lots of money( buckets loads ) , but where there is a crap load of money everything is possible

-------------------------

Now to a 911 that does not have any form of factory A/C , well the electric compressor idea has merit , I am just a bit concerned about little standard alternator and its ( period correct ) small wiring from it & its age is going to be an issue , I would not be surprised one bit ( say in a year or two ) that with the electric compressor A/C system there will be a recommendation to fit a 2nd alternator to the 911 that has the electric A/C comp to make sure that the amperage will be perfect no matter what , I know it sounds like an overkill , but thats a lot better than a very flat battery on arriving at ones destination or not quite making to the destination 

And where better to fit a standard small extra alternator ? 

Answer = where the factory A/C compressor would of been ( there is plenty of room there if there is no factory A/C )

The other obvious thing with the electric A/C ( if fitted )  will be what to do with the lack of air vents in a 911 ( up to 1985 ), may be the return of what Porsche had from 1970 to 1976 & nice under dash ( very wide ) under dash vent system , but naturally this all has to be remanufactured as this vent design spare part from Porsche went NA decades ago 

There is some food for thought 

Regards
Bruce Buchanan 

Edited 28February, 2017 by Buchanan Automotive

[Coastr]

Bruce not sure if you've read the technical documents on the electric AC system - there is some interesting stuff there about power management.  I think the kit connects direct to the battery terminals instead of the alternator and actively reduces the load when there is not enough power available.

But the most interesting part was their heat chamber testing where they concluded airflow was the limiting factor rather than compressor or condensor.  So I think the rest of the work went into coming up with a big fan unit that could blast the air out the factory vents.   I haven't seen it but by reading it looks like they are hijacking the fresh air intake because they say the system can defrost as well as blow through the floor vents, and that it can mix with heat as well.

It all makes for an interesting take - I think the market really is people with no factory AC or people doing a fresh build and deleting factory AC.  You do get a cleaner engine bay, less hoses and better weight distribution.

waiting to hear the reports from the first people in Texas who install and try it out.

[SimonN]

Bruce

I also recommend you take a closer look at the electric AC system. Consider that it has been developed by a good electronic engineering and auto electrical team who has a great track record with other electronic products for Porsches. These guys know what they are doing, and coming at it from the electronics side, I would be very surprised if there were any issues in that area. I agree with you that hose length is a real issue, which is why their system is so impressive. IIRC, the total hose length is under 3.5 metres because the compressor is mounted up front, close to the single condenser they use in the front guard and their evaporator unit which is also well situated. So little hosing has got to be the way to go.

What is really impressive with what they have done is the performance figures they have proven, both in testing in the USA in real conditions but also in a specialist climate chamber used by the automobile industry in the UK and they tested up to 42 degrees C. I also thing their work to identify that the size of condenser was not a factor is really interesting. In their words "We looked to Italy as a hot country with a history of producing small cars with good a/c systems. Can't find a Fiat car or any small city car that has more than one condenser and some of them are tiny. With regard to the comments about having a single 'small' condenser, our testing which was done in a climate chamber at 42 C / 110 F, did not suggest that condenser size was a problem. Our system actually held the vent at a lower temperature than the modern car (that we also tested alongside).

I love the idea of a small, light system that doesn't drain power and works significantly better than the existing system, even with upgraded modern condensers, evaporators etc,  which is easy to fit and which gives some real benefits over anything Porsche produces even today (conditioned warm air for defrost). Best of all is the saving of 18kgs. While I will need to see a bit more evidence, based on what i know so far and their other products, I am really excited about this product and if all checks out, I cannot see any downside other than lack of originality.

 

[Buchanan Automotive]

I am concerned about the said 911 >1989 with an electric A/C compressor sitting in traffic while idling the 1970's style alternator is not coping at idle where alternators do not work much at all , meaning I am concerned about sufficient amperage in these conditions ( meaning battery going flat )

However driving along at normal road speeds( out of traffic congestion ) the amperage that the small last century alternator will produce be higher & more manageable ( may be ), I hope it works , but I am not convinced "Yet" , I may well be later  & I would not like to be among the first to install into a customers car , I think I will wait until its proven in real Australian city / suburban conditions 

Remember , after 40 years working on Porsche's I am not one to take to something expensive unless its a proven product 

Question } in the R/H/D version , how do you get the car battery out( to replace) with the electric A/C pump fitted next to it , or was I looking at a pre production photo ( out of date photo ? )

PS } Plus I have seen , read about ,heard about , talked about so many "air cooled 911 A/C fixes "( mainly for > 1989 models) for sale , mentioned in independent Porsche magazines  in the last 15 - 20 years ( as I am sure you have ) and all of them have been a fizzer or a not what was advertised or just completely useless , so you could imagine I have become more sceptical 

As you said, time and real world testing will tell over the next few years , I hope it goes well

Regards 
Bruce Buchanan

Edited 28February, 2017 by Buchanan Automotive

[SimonN]

PS } Plus I have seen , read about ,heard about , talked about so many "air cooled 911 A/C fixes "( mainly for > 1989 models) for sale , mentioned in independent Porsche magazines  in the last 15 - 20 years ( as I am sure you have ) and all of them have been a fizzer or a not what was advertised or just completely useless , so you could imagine I have become more sceptical 

As you said, time and real world testing will tell over the next few years , I hope it goes well

 

 

Bruce

I think you are right to be cautious. I certain was, but I have been following the project for a long time. This isn't actually something new and to give the developers a lot of credit, they have kept the details quiet while they have been developing and proving the system. It has been subjected to very professional testing to date and based on their other products, which were developed with a lot of testing as well and have proven to be very reliable and do what was claimed, I am optimistic about the product. They haven't rushed the product to market. Most who have followed the project would say they are frustrated at how much testing is being done before they are prepared to sell it to customers. It's hard to know exactly how long they have been testing, because the story on broke after they had been working on it for some time and nobody really knows when they started, but the pre-production version has been on test for the best part of 10 months, ranging from UK to USA driving coupled with the use of the climate chamber.

I understand your caution about draining the battery in traffic, but they have thought of that and have a clever power management system to ensure that when in traffic, the system is suitably regulated. Seeing that the standard system is not that good in traffic, I wonder if this will be an issue. I also feel that as they have been testing it in UK trffic, which is far worse than anything i have experienced in Aus, there is a chance they have got something that is reliable. If it out performs the standard system in most conditions and only equals it in traffic, that would be a huge win.

I can also understand you skepticism having read about "breakthrough" products for our cars that don't deliver or even make it to production. Too many people seem keen to get the market fired up way too early. Although I understand it from a commercial point of view, it is very frustrating as so many fail to deliver. In this case, they haven't even shown the details of the product until it is in production form. I also know of at least 3 other electrical a/c systems projects. This is the only one that IMO, is "real".

I hope to see the system in use in April when i am in the UK. It might not be the best time of year with temperatures, but it should be interesting.

I should add that I have no affiliation at all. I simply admire the way they have gone about this and in the time they have taken to develop the project, i have also been working on a set up using Australian available components. The problem i have faced is the power management issues, which is why i have followed what they have done in this area. i was going to have to use a better alternator and battery, which is still an option with the above kit.

Edited 1March, 2017 by SimonN

[Buchanan Automotive]

Thanks SimonN , going from what you have mentioned in the above post , it sounds much better than I first thought or at the very least a product with a lot of detailed work has gone into it

Good Luck with it

Regards

Bruce Buchanan

[SimonN]

Bruce

It's great to have somebody with your level of knowledge asking all the right questions, which keeps everybody honest and highlights where we need to really be paying attention. And as you point out, until we see it in a car over here, we won't know for sure. Thanks for your contributions.

[OZ930]

The other obvious thing with the electric A/C ( if fitted )  will be what to do with the lack of air vents in a 911 ( up to 1985 ), may be the return of what Porsche had from 1970 to 1976 & nice under dash ( very wide ) under dash vent system , but naturally this all has to be remanufactured as this vent design spare part from Porsche went NA decades ago 

Regards
Bruce Buchanan 

RetroAir actually offers the under dash wide vents similar to, but not the same as, the BEHR vents.

http://www.retroair.com

cheers

Edited 1March, 2017 by OZ930

[Buchanan Automotive]

Yes , that's the idea , the under dash vent design is a good way to get decent air vent volume to the vehicle occupants in a reasonably neat way without wrecking the dash , meaning in a 911 (Pre 1986) that has terribly small dash vents

Regards

Bruce B