Griffiths AC Upgrade Install In '88 Coupe

[TheGanzman]

So, here's how it went down: My newly acquired '88 Diamond Blue 41K miles 911 Coupe wasn't holding a charge. We diagnosed it to a bad evaporator core (we thought) so we replaced it with a new Porsche part - still lost refrigerant. Subsequent hose investigation on the lift showed numerous deteriorated areas on most of the non-barrier stock lines. I made the executive decision to replace ALL lines w/Griffiths barrier hoses; while I was at it, I opted for the "Duel Kuehl" front and rear LR wheel well condensors. Less than a week later, I rec'd my VERY high quality kit. After blocking out 3 days for installation, we put it up on the lift (I recommend this highly if possible!) and started in. Since the evaporator had been recently replaced, all was well and tidy in the "smuggler's box". We ganked out all the old hoses, and proceeded to string the new ones in. Though I was DREADING this part of the job, it actually went fairly smoovely, thanks to well-marked lines AND the car being on a lift. We got all the lines run in maybe ten hours w/2 people - clamped in and ready to go! Mounting the rear condensor in the LR wheelwell wasn't bad either; the front wheelwell condensor was a bit more tricky, due to having to remove the seat belt retractor bolt and install a longer one. I was struck by JUST how ingenious the whole kit is - I've installed "aftermarket AC" in a half dozen street rods, and the Griffiths kit is CLEARLY the best thought-out, with the highest quality components. EVERY fastener is stainless steel, and the kit comes with "more than you need" of about everything. Also, it's fairly "intuitive" to install; we really didn't need the directions much 'til the front wheelwell condensor install, and the electrical part. The directions BTW are OUTSTANDING - even a caveman could figure 'em out!

The devil's in the details - cutting the stone guards proved to be a tedious job, mainly because I'm SO picky, and wanted MY guards to look EXACTLY like the Griffiths guards pictured in the directions! Tracing them out was a bit time-consuming too, and an area for improvement - I'd like to see a set of paper templates for the given year you're working on included in the set, even if they were only "suggestions" which you could deviate from slightly if desired...

Got it all buttoned up at the end of day two (about 14 hours for two people) and got all ready to evacuate/charge the system the following AM. This went pretty well, though we DID have to do the evacuate/charge procedure twice; it is after all 40+ feet of lines! Charlie was available for the 2-3 phone calls we generated, and patiently went over the fine-tuning of the evacuation/charge procedure (he must be getting pretty bored of this by now, but didn't act like it - you would have thought it was HIS car we were working on!) Finally on the afternoon of day three, our efforts were rewarded - 110 degree outside ambient temperature in the sun (thanks to the Santa Ana winds/heat wave!), 51 degrees at idle and 40 degrees at 2000 RPM's, also not moving...

This morning I drove up to "Cars & Coffee" in Irvine, digital thermometer protruding from my center vents. 85 degrees outside ambient, 5% humidity, and 37.5 degrees at the vents on the freeway at 75 MPH. Interestingly, the temp. dropped to 36.5 as I pulled into the parking lot, I think due to the compressor-controlled condensor fans in the Duel Kuehl units - these babies move a LOT of air! As a further experiment, I got home, jumped out of the Porsche, and jumped into my 2007 Chrysler 300C SRT8, digital thermometer in hand, for an A-B comparison. Now HERE's where it gets interesting: I've always felt like the AC in that car has been VERY capable; NEVER had the first complaint - but this was the FIRST time I checked the temp at the vents. Anyone wanna guess? It NEVER got below 41 degrees the entire time, even on max. AC! Which leads me to my conclusion - Feeling "cool" is as much a "perception" as a firm reality. What the Chrysler (and I suspect MOST new cars) do and do VERY well is move a LOT of air, properly aimed, at a very high speed (when set to "Max."). Automotive engineers have HAD to redesign their systems accordingly, 'cause as we all know, R134A is maybe 85% as efficient as good 'ole R12. We of course used R134A in the Porsche, but I elected NOT to go with the Griffiths 30% increased velocity evaporator fan, the "rheostat-like" variable speed fan control, and the ancillary center vent addition that eliminates the center "bow-tie" factory air diverter. My reasoning was that I could always add one or all of those items later without "cracking" the charged AC system. I can tell you, I'll be adding ALL of those items as my budget dictates, after my little A-B experiment today! Not that I feel like I NEED to - the upgraded Duel Kuehl system does do a fantastic job. But most of us have become accustomed to modern automotive AC systems, which have done a great job of making us "perceive" that we're being cooled as good or better than the ole "R12 days". I think that these items in concert with the additional duel condensors will usher my '88 into the modern age of AC cooling. I'm sure too that if I had used the Griffiths serpentine front condensor and the serpentine evaporator, I would have seen additional marginal cooling; mine were both fairly new factory items, so I just couldn't cost-justify replacing them.

In closing, I must heartily recommend this albeit expensive upgrade. What a pleasure it is motoring along in your '80's Porsche will all the windows closed, listening to the confident vaccum-cleaner sound of your air-cooled beast, while you are NOT sticking to your fine German leather seating surfaces! Kudos to Griffiths on a VERY well-thought out product set, executed to near perfection. Thanks too extended to the TruSpeed Motorcars boys that helped me with the lift time and the install - The Ganz is cool and dry!

[mlfox]

Great post, and a good confidence builder for us DIY's out here. This upgrade is on my list.

Regards,
mlfox

[GH85Carrera]

Your experience was just like mine. I love my Griffith' system. I have driven many miles in very hot areas and my 85 Carrera has kept me cool and comfortable. Every part looks like it was built with quality, not price in mind. Top quality is never bottom price. I can't say that the Griffith's system is the only way to go, but I can say that I was very happy with my results. The engineering was very clever and top quality. The tech support was 100% and the result was without compromise.

[mthomas58]

Originally Posted by TheGanzman

Kudos to Griffiths on a VERY well-thought out product set, executed to near perfection.

I too am a big fan of Griffiths A/C upgrade products. Customer support is world class. My adventures chronicled here:

A/C Upgrade Project starts tomorrow!

[ruf-porsche]

Most people think that max a/c is when you have the blower at the highest setting, but in reality max cooling is when the blower is set at the slowest setting. Because you are pushing less air through the evaporator, the air has a longer time to give up heat, where as if you push a greater amount of air through the evaporator it doesn't have as much time to give up heat. Measure the temp at both slow setting and max setting and you will see that at the slow setting the air temp is colder.

FYI

[Jim Sims]

Actually the idea of air conditioning is to remove heat not just reach the lowest temperature coming out of the vents. The lack of air flow from the inadequate dash air distribution systems in the SCs and Carreras is one of the reasons for their poor air conditioning performance. Heat removal is the product of both the temperature of the air and the amount of air flowing. In my experience, to cool the car down quickly, a lot of air flow even if at the cost of higher vent temperatures is generally better especially in the basically closed system of a 911. I'd rather have a lot of air blowing at 45F than a whisper at 34F. Further, if the vent air is in the mid to high 30's ice is likely accumulating in the evaporator (especially in humid climates) and is blocking air flow and ultimately heat removal.

[TheGanzman]

Originally Posted by Jim Sims

Actually the idea of air conditioning is to remove heat not just reach the lowest temperature coming out of the vents. The lack of air flow from the inadequate dash air distribution systems in the SCs and Carreras is one of the reasons for their poor air conditioning performance. Heat removal is the product of both the temperature of the air and the amount of air flowing. In my experience, to cool the car down quickly, a lot of air flow even if at the cost of higher vent temperatures is generally better especially in the basically closed system of a 911. I'd rather have a lot of air blowing at 45F than a whisper at 34F. Further, if the vent air is in the mid to high 30's ice is likely accumulating in the evaporator (especially in humid climates) and is blocking air flow and ultimately heat removal.

Totally agree, Jim - absolutely clear on my little A-B comparison between my 911 and my 300C...

Drove the Porsche today in the heat of the Santa Ana winds, specifically WITHOUT the temperature gauge in the vent. Actually had to turn it DOWN to the low speed fan setting, and had to back the temp. off to about 6 o'clock on the dial. Hell, I might not have to do another thing!

[khamul02]

Jim,
I agree. I still have something up with my AC. It only blows 45 to 50. BUT with the Retro Air upgraded fan it works very well. Tons of air flow. I went through last summer and didn't even track down the bug (which can only be the x valve) down.

[kuehl]

"Max A/C, Max. Cold, etc." We all know what we would really like that to be.

Most ac systems, other than the 911/930, max a/c means "recirculation". On most other cars when you hit the max ac button you can usually hear a change in tone of vent air movement and sometimes a change in the speed of the evap blower (that relative to the resistance or non resistance). This change is usually related to the ventilation system closing off the outside air coming in through the system so that only cockpit air is moving through the evaporator; hence recirculated air. The 911 and 930 use a recirculated air system full time.

The benefit of running an ac system at lower than 40 F temps is when you can't have it any other way, the ventilation system (number of vents, size shape, flow, location, cubic feet per minute) is inadequate. Freezing of the evaporator core under 40F usually happens more near or below an evaporator core temp of 32F and depending upon the humidity. However that is what the thermostat is for , in the case of the 911/930, having the ability to adjust the air temp as well as prevent freezing of the evaporator core (when it is properly set up) by temporarily turning off the compressor so the evaporator core can defrost.

While I'm helping out my kids cut snow flakes to put on the windows for the Holiday I'll ponder on what we can do to resolve the stone guard templates, however part of the fun of installing the system is that you get to put your art talents to work in that particular step.

Enjoy, Stay Kuehl, and have a wonderful Thanksgiving.

Griff

[1982911SCTarga]

The 911 and 930 use a recirculated air system full time.

This is a really interesting point that rarely if ever gets mentioned. I've always thought Porsche was unusual in designing the A/C system this way.

Brian