78SC AC Project Complete - Thanks Kuehl!

[Kftca]

Folks:
I have just completed the repair/upgrade of the AC system in my 78 SC (single condenser layout). Very successful result (in my opinion) as i just completed a nearly 2000 mile trip around eastern Canada and New England and having AC made a huge difference. I used the kit from Griffiths and I would like to pass my Kudos along to Kuehl and recommend that if you decide to tackle the AC, the Kuehl solution is the way to go. There are lots of threads on how to do this, but I'll add just a few lessons learned from my experience;
- A Newbie can do this job. You just need patience, and time.
- Parts quality and fit up very good.
- Everything is included in the Kuehl kit including excellent instructions
- Suggest you purchase the evap rebuild kit as well, as it is important to ensure you get all the air delivered into the cabin from the existing setup.
- Clean/flush everything you intend to reuse. (In my case it was the evap, TXV valve, and condenser). I did not clean or backflush the TXV, this was a mistake as it turned out it was plugged solid with black particulate. (I think it was hose particulate from the degradation of the old hoses). I had to disassemble the system and replace the TXV and then it worked perfect.
- Uncover the bowtie vent and use a Kuehl center vent or a duct or hose to route this this air into the cabin. I used a old piece of duct and I was amazed at how much air came out of this. Really helped in making you feel cooler.
- Test the AC t'stat as well if you intend to reuse this. (Mine was stuck in the on position). Griffiths sells the replacement and it was a perfect fit.
- I want to acknowledge the excellent technical support from Griffiths. Charlie was very helpful in trouble shooting my blocked TXV.
- Lastly, ensure your expectations are aligned with the system capabilities. For me, as i live in eastern Canada, satisfactory AC is achievable with a single condenser system whereas, in hotter climates,ii would expect more modifications wold be required.

Thanks Griff.
~
Karl

[Coastr]

Great start to a thread! Couple of questions:
- which kit did you use? They sell many
- did you reuse your condenser?
- what was the max temp/humidity you encountered on your trip?

[Kftca]

Hello:
To answer your questions,
1 I used the complete kit which includes compressor, adapter bracket to mount it on the old York sole plate, hoses, and drier. I also bought the evaporator overhaul kit, a new ac thermostat and txv valve.
2 I reused my original condenser and evaporator. Both were in good shape. The condenser needed a good fin straightening in a few places which I did with a fin comb and tweezers.
3 Sorry, I did not take any real measurements so my satisfaction with the system is only based on anecdotal opinion . ( I do believe that objective measurements are always best) However I would guess : OAT 75 deg F max, with low rh, vent temp was measured on fan speed 2 = 36 deg F. I also encountered one full day of rain so rh was high but OAT was quite low (maybe 60 deg F or so). AC running on fan speed 1 and windows were alway clear.
Hope this is of some help to you.

[Coastr]

Yes thinking about whether I need to go a second condenser or not, and whether to reuse the Evap and condenser. I’m guessing with the overhaul kit it might work. I need to handle temps well into the 90s with high humidity. I’ve been in sticky eastern summers but sounds like that wasn’t what you had.

Not sure if a modern condenser instead if the original will do better or keep the original and add a wheel well unit. I don’t like the wheel well ones just from the point of view of extra stuff under there, but I guess others have tried and this is the accepted solution.

[GH85Carrera]

Since I live in the hot areas, I put in the Griffith’s dual condenser, 11 years ago. I love the performance it produces with the two original condenser and the two new ones. 4 condensers is needed for really hot days. His products are top quality, and I have put 60,000 miles on my 911 since having good ac.
So 11 years, 60K miles on the rear condensers, Zero problems, just cold air.

[Coastr]

It seems nuts that you need 4 condensers when later models (and cars with similar cooling requirements only need one small/medium sized one.

[Steve Marshall]

Coastr - have you thought about adding fans to your rear condenser? You can get these on Amazon for cheap. Relay, harness and wiring included...

Modern cars use parallel flow condensers which are much more efficient.

https://www.amazon.com/American-Volt-Electric-Radiator-Thermostat/dp/B01GD4ZO7U/ref=sr_1_6?crid=47YINK97X7BS&keywords=american+volt+dual+electric+fan&qid=1561952073&s=gateway&sprefix=american+volt%2Caps%2C163&sr=8-6

[Coastr]

The condenser is in the cupboard in the garage. I’m scoping out a reinstall and trying to figure out best way forward. Fans might be an option. Happy to get new compressor and hoses, I was trying to avoid hanging another condenser if I could avoid it.

[GH85Carrera]

Originally Posted by Coastr

It seems nuts that you need 4 condensers when later models (and cars with similar cooling requirements only need one small/medium sized one.

The air cooled 911 is a weird beast. The factory put one little one in the front with a fan that blows a little air over it, but not much. The one over the engine is most of the condensing capacity. Adding two more in the fender and their fans gives the system sufficient condensing capacity to get all the evaporator can handle. Any less is well, just less. There are also long long hose runs and that makes an impact on the system.

The only original part left in my system is the rear condenser. The compressor is a replacement OEM type unit. Everything else is a replaced component.

Charlie Griffith has almost certainly tested the 3 condenser system vs a 4 condenser system. For Canada and up north, 3 is likely plenty. For my trip to Florida in a few weeks, I want all 4 working hard to cool me and my passenger.