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Classic Retrofit AC Write Up

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Hey Guys, my install is very near complete and when I’m back from travel and have the opportunity to see and experience the kit in my little brown SC, I’ll post up some detailed images and give you the low down (my lowdown). Be around mid Feb.

Getting a few PMs so thought I’d let ya’ll know.

Cheers.

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Mate  I am also interested on your views about the product also looking forward to hearing what you thing about it  ....

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On 21/02/2018 at 10:27 AM, clutch-monkey said:

i believe he is deciding on a colour for the coolant pipes

Jeez...:).

Sorry for the delay in responding but there has been a delay with the car.  Skunk are all done with it and it's been at Nineauto getting the alternator upgraded.  This is actually a good place to start the feedback as the alternator and the entire electrical system needs to be up to scratch for this AC system to work.  In my case I've got a '78 SC with a 75A alternator which didn't have the grunt to run the AC system continuously.  This was in fact something I did know about, but in the process of deciding to put the kit into my SC rather than the Hotrod (I've got another kit ordered for that) I'd forgotten as my mind was dwelling on the 3.6 in the Hotrod which has 110A.

So, my alt is getting re-wound, or the static magnets replaced, to make it 110A.  This is a good solution as it will still fit in my older smaller fan unlike the 110A unit out of a 3.6.  The delay in getting my car back is the autoelec has let Stu down on time frame.  Unsure of cost as this stage.  If you've got less than 90A you will need to do this step.  More amps the better and if you're upgrading then go 110A or wait for the Classic Retrofit 160A jigger that I think is out soon.

There are a number of items (battery terms and earths etc) that all need to be in good working order or new.  Its not big stuff but it needs sorting.  Might be a good point to ask Jonny from CR to confirm what these things are.  @Jonny Retrofit can you assist here?

Next step is for me to get the car back which might be tomorrow, so I'll post up once I've got some seat time.

 

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Got the SC back today.  Melbourne was overcast, muggy and mid to late 20s on pick up.  First impression is that you can't perceive it's running in terms of hearing or feeling the compressor, and that the air is nice and cold.  I drove with the window down as it my preference when I want to be engaged with a car so can't really tell you how quickly it cooled the cabin.  I'll openly admit I've got no idea what the dash levers do other than the fan speed which I had set to max, and the levers are half jammed on my car.  I managed to get it so it was blowing on my feet which was nice and I think it was coming out of the dash vents too but they're so effing small on the SC, who really knows.  Overall I was a little underwhelmed with the amount of air blowing, but maybe that won't matter with the windows up and if the cabin cools nicely.  If you think modern car AC where you literally get a blast of cold air, it's not like that.

To operate you simply push the button and it turns blue and it's on.  I've no idea if it has settings, or if it's simply on / off and it's a matter of adjusting fan speed and where you want the air.  Will have to go back and read the paperwork, which is somewhere...

Re the install I think it could be neater in terms of the wiring etc, but maybe that's me being picky.  With frunk carpet it will probably be very neat.

So, first drive was about 10 klms and that's what I reckon so far.  I guess the options are no AC, traditional AC or this system.  I can't have the trad AC as it would ruin my engine bay with the ITBs, so for me it was a case of no AC or Electric AC and no AC makes for sweaty balls which I'm not into.  As to how the electric compares to the engine driven compressor I personally can't say.  As to cost it's what it is from CR and the target install time is 8 hours.  This is with some more experience of installing the system and is probably double that for the time being.  Again how long this is compared to a trad system I don't know but I'd say that's very little.  Strikes me that keeping the whole thing up the front of the car is a good thing as far as complexity and neatness is concerned, not to mention cost and weight distribution if either were a concern to you.

I need much more seat time over different conditions to provide any real feedback on how it performs and will do so over the coming weeks and months.

Photos.

Button on dash

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New wiper washer reservoir location

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Under Frunk

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i-BJm9zhh-L.jpg

i-qmMTGzf-L.jpg

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I had conventional ac in my sc and it sounds like it at least matches that, whilst weighing less and keeping engine bay clean.

the e9 electric AC is almost as effective as conventional Ac (almost up to modern systems!) but the condenser is absolutely massive due to more space at the front compaired to a 911 front fender.

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I think the issue as you have noted is lack of vent size.  I doubt any AC with those vents could cope with the window open and driving along.  The amount of air coming in the window is much more than the vents can flow.  If you compare to the blower size and vent size on a modern car there is no comparison - I would say the SC vents and blower fan are 20% of the size of my BMW AC which I disassembled and reassembled.

As a comparison, my mostly-stock SC unit performs at it's best on overcast muggy high 20s days.  Anything with bright sunshine and 30s and it is cooling a bit not not keeping it nice.

Am I right in understanding the jack is in a different location now?

 

I think the tidiness is OK - certainly beats engine mounted compressor, condensor and hoses as it can all be covered by carpet.

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Nick,  I'm surprised about your blower comment so think something is amiss.

it is quite specific how to set the sliders to get the recirculation to work so please try this:

For max blower flow,  fan on full and ALL other levers to the left.  Jammed ain't good ;)

Then, just use the top left lever to blend between face and feet.  Fully left is all face which will have the most cooling effect, but I like a little on my feet to slide right just a tad.

Please also check that your heat 'flappers' are fully closed.  Easiest way is to feel the pipes in the front foot wells when you are driving.  If they are at all warm, then the AC is being fed hot air which isn't good.  Often they don't close fully so you could disconnect the hoses behind the carpet and block them if this is the case.

We have a car in Singapore right now and the customer is more than happy so I think you have a little bit of detective work to do.   Check that the air is not leaking out anywhere under the cowl.  Put the blower on full and have a feel aroind behind the blower cover.  

Let me know how you get on.   Btw, having the windows open won't help much!

P.s. See page 12 for lever info:

ac-setup-and-test-manual.pdf

 

 

 

P.s. Your wiring is a little untidy.  The jack should still fit in the car fine:

p1000407.jpg

 

 

 

P.s.  The blue clips on the hoses are meant to be taken off after they are crimped.  Clip off very carefully with sharp side cutters.

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19 hours ago, Coastr said:

I think the issue as you have noted is lack of vent size.  I doubt any AC with those vents could cope with the window open and driving along.  The amount of air coming in the window is much more than the vents can flow.  If you compare to the blower size and vent size on a modern car there is no comparison - I would say the SC vents and blower fan are 20% of the size of my BMW AC which I disassembled and reassembled.

As a comparison, my mostly-stock SC unit performs at it's best on overcast muggy high 20s days.  Anything with bright sunshine and 30s and it is cooling a bit not not keeping it nice.

Am I right in understanding the jack is in a different location now?

 

I think the tidiness is OK - certainly beats engine mounted compressor, condensor and hoses as it can all be covered by carpet.

When Nick masters the sliders the vent sizes are just about ok but only because we have reconfigured them differently.  Now, we can get AC air out of the centre, both side vents and the footwells.

It is only in quite recent years that car AC works with the windows open but still not as well as when closed.  We are still fighting (and loving) a 50 year old car!

 

 

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I'm with Coastr, unless the face vents - centre and sides - on the pre'87 cars is supplemented with additional face directed vents, the AC's not going to feel effective.

The post '86 cars, 964's and 993's with their much larger standard vents and air volumes cope OK, albeit without to much margin.

Jonny,

Could your unit be reconfigured to supply additional underdash vents like the Kuelh ones or even the old Behr style full width ones? 

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7 hours ago, Peter M said:

I'm with Coastr, unless the face vents - centre and sides - on the pre'87 cars is supplemented with additional face directed vents, the AC's not going to feel effective.

The post '86 cars, 964's and 993's with their much larger standard vents and air volumes cope OK, albeit without to much margin.

Jonny,

Could your unit be reconfigured to supply additional underdash vents like the Kuelh ones or even the old Behr style full width ones? 

Re read my last post.  We don't use the vent system like Porsche did.   Until Nick sets the sliders correctly, the system won't chuck out as much air.  

Adding more 'registers' does nothing for improving airflow, it's just a marketing trick.  Loads of vents equals loads of air, right?  No, same amont of air, just moving slower.  The restriction is the cross sectional area of the duct work.  We have about twice as much as the Porsche system.

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Jonny,

My point is that it needs to be done together to provide the comfort we are after.  More flow capacity plus bigger vents just like modern cars have so there is a comfortable balance of greater volume but pleasant velocity.

There is a reason that no modern car has side vents the size of pre '87 911's.  No marketing trick at all.

Certainly interested in your evaporator setup though.

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Sorry, what I meant was the Porsche aftermarket 'underdash' systems with a row of vents are a marketing trick.  If you look at the back of them, they all connect back to a single 80mm duct!   You may as well have one vent with faster flow.

 

Please also refer to page 27 of our main install manual on this page http://www.classicretrofit.com/electrocooler-complete-kit-for-911-1974--1989/  The way our system runs gives you two additional hidden body vents which makes a big difference.

So we have:

Centre vents on 1 X 60mm duct

2 X Small side vents on 40mm duct

2 x hidden vents on 60mm duct

Total 11,000 mm2 cross section

 

Compared to an original or aftermarket Porsche AC system which has just 1 x 80mm (5000mm2) duct for the whole system!  

Hope that makes sense.

 

 

 

 

 

 

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Thanks!  Page 27 and a page or two either side explained the thoroughness of your design and the foresight to include the extra hidden vents.

Has anyone asked if you sell the evaporator alone as an upgrade for the standard set up?

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Here are the airflow measurements (made with a handheld anemometer).  

Engine at idle, battery voltage 14V (battery voltage affects fan speed).

Both centre vent registers open and facing straight ahead.  Small side vents rotated to the 'down' position.

Max face level cooling:

Fan on full,  All other levers left.

Centre vent:  2 x 7.1 m/s

Small side vents.  2 x 7.0 m/s

Hidden vents.  0 m/s

Full body cooling:

Fan on full,  Top lever right.  All other levers left.

Centre vent:  2 x 5.5 m/s

Small side vents.  2 x 5.1 m/s

Hidden vents.  2 x 7.5 m/s

And some maths...

You can convert the air speed readings to volume of air moved based on the vent sizes and this gives the following for both settings:

Max face position:  78 CFM 

Full body position: 120 CFM

We estimate the air volume in the cabin of the 911 to be approximately 50 cubic feet.  So in other words, to recycle the whole cabin air through the evaporator takes roughly:

38 seconds on max face

25 seconds on full body setting.

There will be some losses due to air leakage and the windows must be shut or the cold air just gets pulled straight out the window.

Perversely, even though less air is exchanged, the max face setting can 'feel' colder as your head is more sensitive to temperature.

(Peter, yes the blower / evap is available individually - listed on our website.  A guy in Dubai has got one.)

 

 

 

 

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Ok, here is a shit photo of the dash HVAC levers under the dash. Essentially the cable on the bottom lever (which is the red one) is bent, and as a consequence is fouling the lever above which is the one that needs to be hard left. It has its only problems too as the cable sheath seems to be stopping it moving completely freely. 

The engine is running like shit and needs to be tuned properly so I think I’ll throw it back in the workshop and get that attended to, and get the HVAC controls fixed too. Bills bills more bills.

Once done we can problem solve from there.

@Jonny Retrofit I’m not convinced the system isn’t cycling like it was for Rohan before alt upgrade as I sensed it got cooler then warmer in cycles when driving on the hwy. I could be wrong but if I can plug in a cable and interrogate it that might be an idea too. Also why don’t I have the natty CR cover on my compressor as it looks ace and really finishes it off? Question for you or Rohan?

Cheers.

Ps never look under your dash as it’s scary!

i-82FR8jv-L.jpg

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looks like you have a kink in the cable to the long bell crank.  This in itself will give you grief.

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1 minute ago, OZ930 said:

looks like you have a kink in the cable to the long bell crank.  This in itself will give you grief.

Yes kink. Yes grief. Grrr.

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Ouch, bent cables.  The red lever must also be fully left for the AC to function properly.  If it isn't, the recirculation will be goosed and the AC will not pull the hot air out of the cabin. 

The top left slider connects to the lever on the front left of our blower.   If the lever is screwed,  you could loosen the adjuster screw on the lever and set it 'manually' from the frunk.  Left would be full face and right would be full body.

Potentially, if someone adjusted the cables in the frunk with them bent, then the whole shebang could be misadjusted.  

Did Rohan do the under dash 'snorkels' on your car?  Makes a massive difference.

Natty cover?  Do you mean the sticker with our logo on the ECU case?  It was a bit too 'showboat' for me.  I have a transparent yellow case on mine so I can see the internal led indicators, you have the boring old black case, more befitting of the Porsche way...  I can send you a sticker if you insist.

 

p.s. If it makes you feel any better, I got my SC out today for a winter blast as it was sunny but crisp here.  Had a great time until I got stuck behind a salt spreader in full deployment.  I'm sure I can hear the rust eating away in the workshop.

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