Porsche A/C
 

I have/drive a SC coupe in deep south Georgia. One hundred plus degree weather is fairly common during the summertime. I too decided to upgrade the a/c in my car, doing so over a period of several years. The first steps were to replace the York type compressor with a Sanden 507 and to replace the old hoses with home made barrier hoses. I also added a Pro Cooler at the same time as I was changing from R12 to R134. That helped a good bit, but still was not where I wanted the a/c to be. Next step was to delete the "bowtie" air diverter under the dash and replace it with an additional center vent. A bit later, I added the Keuhl end vents, again a bit better. My latest mod was to replace the front condenser with the "Desert Duty" version, replace the rear condenser with a new stock unit and to replace the evaporator core with one of the new serpentine type units. Again, better air. Most recently, I have replaced the front valence with one that has a place for a front oil cooler. Instead of moving the oil cooler there, I am thinking of moving the front condenser from it's hidy-hole spot to front center behind the airdam. There will be room also for fans for slow city driving. The other thing that I am considering doing is to put some small computer cpu fans in the ducts going to the side vents. I found some that are 12volt and are only 40mm in diameter. With the addition of a square to round adapter on each side, it will fit the existing hose size. Even without these last couple of mods, my a/c will keep the inside of my car "comfortable" but not frosty. Eventually I want to get to the "frosty" level!

Good luck with your project!

Yours is a perfect example of the snake oil salespersons selling you FIRST, slight system improvements without having you first address the core, BASE problem.

IMMHO the very first thing you should have done is buy/install any one of the fender mounted condensor/fan combined systems. I suspect, am of the belief, that had you done that initially none of the other purchases would have been a true requirement.

The ProCooler, for instance, was likely a step backward, simply making the compressor work all the harder. The only time you are likely to have "excess" refrigerant cooling capability DOWNSTREAM of the evaporator is AFTER the cabin/atmosphere has been cooling down to your satisfaction. And most of us, at that point, would be throttling back on the compressor dutycycle anyway.

Interesting. I didn't know you had airflow data for this. Could link to the post where you shared that experimental data with PP readers?

Thanks.

I did Retroaire, and although it was a new install I am quite happy with it. I ended up deviating from the plan (put vents in console, used the Porsche AC compressor mount etc), but it works well. Good parts, good support from the vendor, not so good instructions but I was able to get it to where I wanted it fairly easily. I did the charging myself (R134a).

Dennis

wwest - where do you live? I'll ship you sensors to test your car with since you seem to think it's easier to send your car across country. Why do you never respond to my comments when I say we'll get you setup with someone local?

John Walker's Workshop or Redmond European could (and does) do anything with respect to 911 AC. They could do the pressure test that answers the "overpressure" hypothesis. IIRC, Redmond European has a leak detector that could sniff the connections for refrigerant leaks. The very simple answer as to why he doesn't take to these experts is that once his hypotheses are shot down, he'll have no reason to further bash Griff. He takes great pleasure in it, obviously.

Hell, I'd help pay for all these tests.

You don't seem to understand. Here, where I reside, east side of Seattle, most days the factory A/C system will be quite adequate. Only exception might be a long commute in stop and go traffic on a relatively HOT day.

But my business of years ago required me to travel to the eastern WA, high desert area, Wenatchee, Yakima, TriCities. And...Amazingly as it may seem my wife and I both enjoy(ed) traveling (KS, NB, OK, AR, TN, MS) with the '78's Targa top stowed but with the A/C at full blast.

So I began experimenting with how to improve the A/C capability of the system.

I can't say for sure today but I suspect the kernal for my idea came from recognizing that the aftermarket availability, and obvious success, of the fender mounted condensor fan combination played a hand in my solution.

Was an additional condensor needed or would simple more consistent airflow through the existing condensors suffice..? Know that Porsche made this veru same first step in improving the A/C performance didn't hurt.

By his posts I'd guess he is in Seattle. A heat wave there is 72F with 45 minutes of full sunshine. Bingo! :D

Doesn't matter. Whenever I ask him to line up his car with another, he stops responding to me. So, anyone willing to go this far on the keyboard on literally *every* AC post, but, won't provide a lick of hard evidence, and avoids all posts asking him to demonstrate this with another car - should tell you that he's probably a bit scared what the data will say.

Were I to have a profit stream as a result then maybe.

This is place where your credibility starts to fall down. "Adequate" in Seattle would be "holy crap it's so hot in this car - WTF is up with the AC" just about everywhere else. Over here in E. WA, the stock system just can't keep up. *Even at freeway speeds*. You know, when all kinds of air is moving over the condensers. Right there, this little tested fact shoots your decklid fan mod down. Makes it moot. Puts it in the grave of half-baked ideas.

I have no doubt that in Seattle, you find very little use for AC. Heck, when I lived over there, none of my cars had AC, and I never gave it a thought. Open the windows, and presto! plenty of cool-enough air. When you start making comment about Kuehl and the aftermarket products in general, everyone but you understands that your opinion is worthless. You don't have the experience to offer an informed opinion, and you don't have the test data to verify your hypotheses. Another reason your opinion is easily rebutted. This is a technical forum - why do you constantly avoid offering test data? (Wait for it, here comes the subject change(s).)

Again, as many SOUTHERNERS have dutifully pointed out, in the climate conditions readily available to me ANY Porsche factory A/C system of the era of concern would provide A/C cooling capacity just as adequate as mine with the fan modification.

A comparitive test with a fully dressed out Kuehl system in the deep south on a HOT and HUMID August day would be the only was to quiet the naysayers, and justifiably so.

PM sent regarding Griffith's system and my experience.

WHAT? You want to make money from the deal? Someone want to pay for the test to be done, but you want the further step of lining your pocket? Unbelievable.

Here's what's to prove - that actual pressure in the system rises like you say it does. You *hypothesize* that this is where the refrigerant goes. I do not agree that your hypothesis, because others claim that you are mistaken - others that have more credibility. Now, you don't have to prove that your hypothesis is grounded in reality - that isn't what ANYONE is asking. We have been asking you to actually hook up equipment and prove, with actual testing, that what you offer as a hypothesis is actually happening. In actual reality. If the system DOES NOT behave as you claim, then your refrigerant loss hypothesis is false, you will have either form a new hypothesis or accept the already-tested solution as valid.

Your attempt to recast the question is becoming a tired tactic.

"..everyone but you.."

How about those that have added rear lid condensor cooling fans with stated

Jeepers jumpin Jehovah. It always amazes me how far sideways these threads go.

The guy just wants some useful information.

Key word. Useful.

I try to send the OP a PM to let him know what is going to happen to his thread before it gets to this point.

Has anyone ever actually tested the "hypothesis" that the refrigerant leak results ONLY from the use of non-barrier A/C hose. Used the old o-rings, connectors, etc. Has anyone, anyone, changed ONLY the hoses. And if so what was the result? High system pressures STILL resulted in leaks...??

Well, not really. My a/c system would not hold pressure very long (a few months at best), R12 was even then expensive and I did not like working around the York type compressor in the engine compartment. Knowing that I was going to swap over to R134a coolant, it was also necessary to change the non-barrier hoses and dryer. Siince I was going to replace the dryer anyway, I decided to give the Pro-cooler a shot. Changing to the Sanden compressor took several pounds off the tail of the car and made it easier to do things like adjust valves and change plugs, etc. While the first steps did not make the car as cool as I wanted, it did improve the situation noticibly. It was 2-3 years later that I did the other work. There actually seem to be two real problems with the SC a/c. The first is that there is insufficient air coming from the dash vents. The end vents especially are too small. The second problem is that the front condenser is not in the air stream. The fan that blows thru the front condenser does not move enough volume of air to do a proper job. When I got around to replacing the evaporator core and the condensers, it was largely because they had been abused over the years with lots of fin damage. As I said earlier, I will likely move the front condenser to the center of the air dam where it gets a healthy flow of fresh air and put a couple of small fans behind it to use in slow traffic. Once the two real problems are resolved, insufficient air flow from the dash vents and over the front condenser, I fully expect my a/c to work as well as in any other car.

You are being deliberately obtuse.

Nobody disagrees that your hypothesis on working fluid loss is plausible. But the difference between "plausible" and "that's what is happening" is where the disagreement comes - not because the possibility doesn't exist, but because the possibility has no data to support it. The counter hypothesis - that 40 feet of non-barrier hose fixes the leaking refrigerant problem, well there have been more than a couple of folks who have testified to that. So, they replace the hoses, and don't have to recharge their systems. I would suggest to you that this very strongly implies a problem with the hoses, and not system overpressure. But you can show otherwise by showing not only system overpressure, but leaks from the o-rings.

You shifting the burden of burden of proof from your own hypothesis to someone else's is transparent and tiresome. If the system pressures track as you say, hooking up hoses to prove it will be simple and easy. The "profit" to you, personally, is that you have actual data - so you get to shut up the "naysayers" as you so cleverly call them.

Shut up the naysayers...no hope absent 3 or 4 of them as witnesses.