A/C Compressor & Condenser Replacement

[dr bob]

Oh --

My target suction pressure is about 20 PSI at the conditions I described above. Your gauge set has equivalent temps for the indicated pressure, and lower/colder is better provided you are still delivering liquid to the expansion valve. Heat from the cabin is boiling the liquid inside the evaporator tubes, and the heat required for evaporation is what "cools the air". My high-side pressures range up to -maybe- 225 on the hottest days, but are determined by compressor and condenser/fan capability, heat load from the cabin including condensing that humidity (as suction pressure), and of course ambient temps.

Note that these are my 928 numbers, but shouldn't differ much in the other cars. For the 928, a clean-sheet project allowed the engineers a chance to include plenty of A/C capacity that the 911 series cars lacked. Folks who have owned air-cooled Porsche cars already know that A/C was an afterthought at best, something no true purist owner would even consider adding. With the US and particularly California markets becoming large fractions of Porsche's world efforts at the time, working A/C systems were a top priority. The head of the 928 engineering and design effort was pilfered from GM, where Frigidaire was already pretty good at maintaining cabin comfort. The 924/944 series had the advantage of all of VW/Audi's accumulated knowledge too as well as their parts bins too. No excuses for suffering in the heat!

[JerVegas]

Thank you for this write-up!


Jer

[Gaspowered]

@Tom , great write up.
This is something I need to tackle before it gets too warm to drive around without cold a/c.
Did you use Griffiths house branded "Kuel" compressor, or the Denso unit?

Cheers

[Tom]

@Tom , great write up.
This is something I need to tackle before it gets too warm to drive around without cold a/c.
Did you use Griffiths house branded "Kuel" compressor, or the Denso unit?

Cheers

I used the Nippondenso compressor. I didn't see the benefit of the Kuel and it sounded like you needed to modify a few things to make it fit. I'm sure they are fine, and maybe I missed the point, but I'm very happy with the Denso version.

[JerVegas]

I used the Nippondenso compressor. I didn't see the benefit of the Kuel and it sounded like you needed to modify a few things to make it fit. I'm sure they are fine, and maybe I missed the point, but I'm very happy with the Denso version.

Yeah, I didn't like the "You must cut off one ear" part of the Kuehl compressor install Description on that site. Felt a bit hacky. Never mind my sense of humor picturing Van Gogh under his 944.

Jer

[c5_pilot]

So I am about to order the compressor reseal kit as my shaft seal is leaking. How many people have replaced the barrier hoses? I get with the age of the hose it’s probably good practice to replace, but they’re a little spendy.

[Tom]

So I am about to order the compressor reseal kit as my shaft seal is leaking. How many people have replaced the barrier hoses? I get with the age of the hose it’s probably good practice to replace, but they’re a little spendy.

Looks like they are $189 now? I don't remember paying that much for mine, but I'd still do it if using r134a. I won't pretend to know the science, but all credible sources seem to say that r134a can permeate out through older non-'barrier' hoses. It's hard to replace ALL of the old hoses, but every little bit helps and this one is low hanging fruit. Just my 2 cents (spending your money ).

[JerVegas]

I got the barrier hoses... I figured it would just be dead easy to do now, with a new condenser, compressor AND drier going in. If I'm going to bolt SOMETHING back on, I'd rather it be new too. Same effort, if a few more bucks. Same with the belts.

[c5_pilot]

Yeah, that’s what I figured. It’s one of those things “ while in Rome” . I dislike rework.

[JerVegas]

It's the old adage "If your car breaks, fix it faster". Once the labor is done, it shouldn't just work, it should work better than ever before. That's what motivates me. And I also hate the idea of screwing a janky old part onto a shiny new one... LOL...