Rennlist Techies, does anyone know how many 928s were made with “rear A/C” (Option Code M570) between 1983 and 1995?

 

Rear AC started in 1985, there are 5268 US market cars with rear AC between '85 and '95.

Unless it was specifically not reported before 1990 in the ROW market, the first ROW car with rear AC is an early 1990 GT in the German market. Between '90 and '95 there are only 124 ROW cars with rear AC.

 

Thanks Rob! It's interesting that so few RoW 928 had rear A/C. Maybe they knew something that we didn't?

 

Germany is colder than the US. Only east germany has continental clima. Here the few hotest days in summer have ~ 95 degrees Fahrenheit.
German 928 cars haven´t the rubber and interieur destruction from heat like california cars.

 

Karsten, thanks for the feedback!

I started this thread b/c I was trying to get data on "rear evaporators" to help my mechanic convince a German company to make a limited run of rear evaporators. As you may know, Porsche and Behr make them NLA back in 2007. Currently, mine is leaking and my repair efforts have yet to work. My mechanic found a German company that has the parts and could make them, but doesn't have a business case yet to do the "retooling".

Are there shops over there making an "aftermarket" version of this part over there, to your knowledge?

 

They did.
They knew that there wasn't enough condenser to get a solid stream of Freon to both the front and the rear expansion valves, at the same time.

 

Greg, are you still selling your A/C upgrade which adds the secondary condenser and associated condenser fan? Is it sold as a kit? Also, is there a way to install it that doesn't delete the washer fluid reservoir?

 

The use of a sun blocking foil on the rear Windows is an effektive way to help the ac.

 

Karsten,

Thanks for the tip. My car came with dark window tint; but had to "lighten it up" so the car would pass state inspection (which it did).

My challenge isn't the A/C efficiency; its Freon containment. Since the "928 Wizards" made this rear A/C option as a "dual evaporator" system, a leak anywhere in the system means no Freon for any part of the system. There are aftermarket choices for the front evaporator; but, none for the rear evaporator. This probably is due to the limited number of rear evaporators sold overall (5258) against the total number of 928s sold (~66,000, I think). So, for months now, I've been on a quest...After mulling over all of the possible options--e.g., deleting the rear A/C by blocking the lines with JB Weld or repairing the rear evaporator either by re-bonding the copper tubes and aluminum core or using "Loc-Tite, Acetone, and Tape"--my mechanic found a German company who said, after researching my VIN, that they could make new ones--that is, if I can place an order for 100 of them at a time. Currently, my mechanic is trying to see if they will do a smaller order. If not, my next option would be to try to get them to make the parts (assuming that they don't already have them in inventory) and then find a state-side shop to do the assembly.

However, given that you are IN Germany, it occurred to me that you might know some in-country radiator shops (small or mid-sized) that might want to satisfy desperate 928 folks who want working rear A/C systems. What do you think? Can you help a fellow 928 owner who is down on his luck?

 

No. A bit complex, as a kit.
And I never felt like/could rationalize sitting down, for two days, writing instructions for the few kits that would be sold. (Although I did a
spend a couple of days starting these instructions.)
The other issue was the cars and the people. The cars invariably had leaks and other issues, which people could not realize that they needed a functional system, before they could start improving it.
Funny how that works!
I think this "kit" is destined to always be an "in house only" thing...unless I get a sudden burst of interest, making it worthwhile to build a bunch of them and finish the instructions.

 

Have you tried shopping for a used unit? Are you sure it is the rear evap leaking,as the connection is very prone to leaks for some reason. I usually find that the o rings in my 86 are starting to bleed R12 out of the system every 6 to 7 years.

 

I think the Job is to difficult. Nobody of my near Business contacts repairs coolers anymore.
New parts are the way to go or an old good unit.
I can order parts here and ship it over the big pond but engineering is way to time consuming.
928 International has nothing?

 

928 Fixer,

Yes, I got a used one from 928 International; however, it too had leaks. I've been working with a radiator shop to try to repair it. but is seems to be putting up a struggle. This is why I’m on a quest—hopefully not a Quixotic one—to find a new rear evaporator.

Yes, the rear evaporator is leaking. A dye test identified the leaks in the rear evaporator at some of the joints between the copper tubes and the aluminum core. Why the "928 Wizards” didn't make the whole thing out of aluminum I don't know. On the other hand, this OE design has lasted ~32 years, so who am I to judge.

The same dye test that found the leaking rear evaporator also identified leaks in the OE A/C hoses. As you know, the "928 Wizards” designed the OE hoses to leak R12 to avoid anyone ever over-pressurizing the A/C system. Unfortunately, I didn’t find out about this until this year. So, when I converted my 928 last year from R12 to R134a, the hoses leaked more. This s why I'm replacing them with barrier hoses.

Life would have been so much simpler if it were just the O-rings.

 

Karsten,

It seems repairing evaporators and radiators--especially ones made from dissimilar metals--is a lost and/or dying art. I would love to get a new part; hence, "the quest". I just have to find the right manufacture. I found a new Behr evaporator used on a "Vito Transport" (see below) that would fit the rear blower box. However, my radiator shop tells me that the modifications to the inlet and outlet tubes to have it match the OE tube locations--so it could mate to the expansion valve--could introduce more weak points that could manifest into new leak points.

Why is such a small part so hard to make and/or source? Wouldn't it be nice if someone in "928-land" had a new one just lying on a dusty shelf so I could buy it? Yes, it would be...

 

Given your observations wrt your customers, it makes me wonder how many folks drive their 928s sans A/C. Hmmmm.....