Classic Retrofit A/C Experience & Guide

[Jonny H]

I must thank Chris for a number of reason. First and foremost, he has been patient and calm with working through getting his system commissioned.

As he states, Florida climate is not easy on any AC system, let alone one that uses one fifth of the power of a regular mechanical system. We also only use one small condenser so the system is all about efficiency.

Chris has been into the system a lot deeper than most folks. This has been in part to help us both understand how to get the best out of it in extreme conditions. I realise that some people reading this will probably be thinking that adjusting all these parameters look really complex. For the most part, you don’t have to know about this stuff, but Chris has taken time to add some detail here and to explain the inner workings. Thanks Chris!

Finally, we live in the UK so we don’t have access to hot and humid conditions. Getting real world feedback has been massively helpful so I’ll be forever grateful.


THANK YOU CHRIS!!!

[Jonny H]

Originally Posted by Discseven

Exceptional AC posting Chris.

Am curious, and forgive me if I missed it, what controls electric AC's compressor's cycling if there's no temp sensor inside evap?

Electric compressors change speed rather than cycle. We found that regulating the speed based on cabin temperature works equally well to evap temperature.

[austria3]

I do not want to ruin this thread so I only post a link to my install report thread where I have shown my foot well / blend valve cover design

[Duc Hunter]

Stefan, no worries. Thanks for sharing.

Jonny, agreed most don't need to know all the details. Since we went through a lot of things getting my systems to where it is today I thought it was a good idea to share them though. As others “run into issues” hopefully they can come here, see that I struggled & my systems current performance, and where to find some performance and where not to.

To everyone, I am still playing with some of my settings etc. As I learn more I will try to post it here.

[Hi_Fi_Guy]

I live in Arizona and truly appreciate this thread. I believe this documentation will help others who are interested in purchasing and installing this system.

[rrcrawford70s]

I recently had the kit installed in my '73 911. I also had the CR alternator installed.

Here are my numbers..

The fan was on the highest, 3rd speed.

Using the software, will I be able to increase the amount of air coming out of the 2 footwell locations and lower the temp?

[austria3]

Originally Posted by rrcrawford70s

The fan was on the highest, 3rd speed.

Using the software, will I be able to increase the amount of air coming out of the 2 footwell locations and lower the temp?

No you only can set the cabin temperature to a lower level. But if you believe there is not much air coming from the foot well you might want to check the setting of the leaver of your exiting ventilation system. The new blower does move much more air volume. You might want to check that there are no leaks and the air is directed to the location you intended to.

I would stay with a fan speed a 2

[GH85Carrera]

Great write up. I did not read it all, as I have a good working system.

One question, do you have rough ballpark on what the overall cost from start to finish? I know it is not cheap, and none of the AC systems that work are cheap.

I was in the Florida Keys this summer. My car sat in the sun for a hour, while we ate lunch. We got in to head further south at 35 MPH Florida Keys speed limit. The car was boiling hot at first, within minutes it was cooling off, and in 30 minutes I had to turn the fan speed back because we did not need more cold. Our glasses would fog up when we got out of the car. I have no temps or measurements, just the observation the system flat works.

Welcome to the world of COLD AC from a air cooled 911. It is a great place to be!

[paulmose]

Chris, even though I went with a Griffiths system (I was so close to yours but Griff was more inline with my budget) I have learned so much, thanks.

You mentioned some changes in your vents, I just did about the same thing, adding the F-150 vent on the left, moving the gauge, and adding a vent to the radio hole, using the Porsche radio blanking plate. I found Dorman, a company that makes vents for large industrial trucks, their 216-5101 vent (Amazon, $10.80) looks sensational in the radio spot.

Good luck and thanks again for all of your info.

[JK 911]

Looks great Paul!

[plasgar]

Chris-

Do you have any updates or findings after a year of running with your new AC? For those of us looking to get into one I know one of my questions is the long term. I know the factory ACs have many problems but I know I can get parts. So at least an update on how the system has held up for a year could help out. Thanks!

[Jonny H]

Originally Posted by plasgar

Chris-

Do you have any updates or findings after a year of running with your new AC? For those of us looking to get into one I know one of my questions is the long term. I know the factory ACs have many problems but I know I can get parts. So at least an update on how the system has held up for a year could help out. Thanks!

Update from Chris here:

Classic Retrofit: Lightweight Electric Air Conditioning

[gremlin]

When you turn the system on how fasts do you expect to see the temp come down? On mine the temp in the evaperator dropped maybe 2 degrees in 5 minutes. It doesn’t really feel like it gets cold. I can see the compressor on and the cabin temp and evaporator temp are about even when it starts. The set point is 5-6 degrees below that reading

I think it’s probably not working correctly


Sent from my iPhone using Tapatalk

[Jonny H]

^ that doesn’t sound right. Let’s say it is 28C ambient.

Compressor takes maybe 30 seconds to ramp up speed, then the evap temperature should drop below 5C in a couple of minutes.

This sounds like you have lost gas or have a leak.

[plasgar]

Jonny-

Checking to see if your site contact submittal is working, I understand if it is just backlogged. I have some questions about your current order system and recommendations for an 88 911. Do I need to resubmit on your site? Thanks

Gary

[Jonny H]

^ it should be. I personally answer all enquiries but it can take a while at peak season. Typically I get 10 non trivial questions A DAY! I am also overseeing development, tech support and shipping so fairly busy!

[plasgar]

Anyone have experience with removing the footwell blowers during a full AC replacement? I need heat in the winter for defrost/defog. Does the new retrofit blower move air from the heat exchangers well enough to remove the footwell blowers?

[horolicious]

I have been running a CR AC in my car since Spring 2019. I have a black car cabriolet. I adapted your settings and ran it this summer. There is an improvement. Thank you.

Sent from my VS996 using Tapatalk

[Duc Hunter]

With lots of A/C and electric A/C threads pooping up recently I thought I would address my current performance. I am still running the same Classic Retrofit system that I installed in 2019. My car went thought a 15 month partial restoration (rust repair) recently, and it's been bloody hot here in Florida lately. I am still running the same settings as noted above, the same software version (I know Jonny, I know!!)......nothing has changed since 2019/2020 with the system. The car....well now its got all it's metal, all the holes in the frunk are plugged, it has a new custom built front bumper, and its metallic blue vs black.

Old black/white version of the car (was a Rat Rod, pictures make the paint look much better than it was)......


New (Gemini Blue, and pictures really do not do this color justice).....


I took these the other day to illustrate how well the CR system is working for me in very hot and humid Florida. On this day humidity was 65%, air temp in the shade was 96F, feels like was 115F. Car had been sitting in the direct sun for 4 hours (12pm-4:14pm). As many of you know high humidity really loads the A/C more than just hot/dry temperatures do. Personally I think this performance is pretty dam good. This is my my 1975, with no heat insulation in the roof, or the rest of the interior, and with an RS carpet kit and door panels. My 1989 3.2 has its normal full interior...which has carpet padding and insulation foam in the roof, factory insulation mat on the rear package tray etc....which would help a lot more. Remember CR has now produced several new software versions, a much improved blower over mine, etc. This is the performance of their Generation 1 systems with 2 condensers from 2019.

When I started (4:14pm) the car the vent temp was 123F (fan only, compressor had not kicked in yet).


3 min later (4:17pm) vent temp was already 67F. I was feeling comfortable with the air blowing on me, and the car was still warm for sure, but my passenger and I were not sweating and were getting comfy. The car has SC style dash vents, and a vent replacing the fuel gauge (most people replace the clock).


9 minutes in (4:23PM) vent temps were 53.6, fan had been turned down to #2 several minutes before (we were plenty cool and comfortable), and the blue gauge in the background shows the evaporator was 43F (5.9C on the gauge).


13 min in (4:27PM) vent temps were 47.8F, evaporator temps were 37F (2.8C), fan was on 2 still and we were SUPER comfy/cool.


18 min in (4:32PM) vent temps were 45.4F, evaporator was 36.5 (2.5C). The system had backed off to maintain temp long before now.

[RDM]

Great info. Thanks for the update!