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So the summary of your upgrade is this:

- Griffiths front condenser
- sandwiched condensers in tail
- Griffiths fender condenser and fan

Is that correct?

Based on your experimentation, it didn't really start working until you added the upgraded front condenser and the fender condenser?

I'm trying to scope out the rebuild of a SC system and was hoping that upgraded front and rear tail condensers with fan on rear would do the job. Seems like that would only work up until about 90-95?
Old 08-16-2019, 07:49 PM
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Quote:
Originally Posted by Steve Marshall View Post
GH85 - That's some serious AC stress tests you've put your system through. I've not road tripped yet and I'm curious how performance will be over time.

Throughout his AC adventure I would stop in a parking lot and idle for 10 minutes to see how hot the engine got. It never exceeded 2/3's hot when the ambient was in the mid 90's. Which is about as hot as it got before I started messing with the AC. This didn't concern me at all but I decided to add a 7" fan to the oil cooler just to be safe. It's a cheap and easy upgrade. It's not connected to a thermostat it but it is wired to run only when the AC is on. I figure if I'm not not running the AC, it's not hot enough to need the extra cooling.

It's hard to tell for sure, but I'd say with the addition of the fan the temp now stays between 10 to 15 degrees below 2/3's hot.

I'm not convinced fans on the condenser are an engine heat issue. I can see in how in theory it might be? Maybe? Kinda? But in reality I'm not experiencing it. How can more airflow at idle hurt?



The ONLY important measurement is driver comfort, and engine temps that are not hot. More air flow is always a good thing on a air cooled 911.

The fans on the rear condenser are blowing warm air into your engine, and the added air flow to engine cooling is negligible compared to the giant fan powered by the engine for engine cooling. As long as the air flow is enough, and it sounds like it is, you are golden.

The main thing, enjoy driving your cool car in the hot summer now!
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Glen
43 Year member of the Porsche Club of America
1985 911 Carrera; 2017 Macan
1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!
Old 08-17-2019, 07:27 AM
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Summary in order of trial and testing:

Sandwiched two universal PFC condensers, 12 x 26 and 11 x 20, in tail with 2 x 7" fans (OE front condenser removed) Cooled just fine but couldn't keep up over about 20 minutes in 95°. I suspect I was getting evaporator freeze up but didn't know it. For all I know this solution was all that was needed?? I didn't figure out the freeze issue until later on.

Added Griffiths front condenser and figured out thermostat setting and properly located the probe in the evaporator. This brought the temps down a few degrees and the system kept up on longer drives.

Added 12 x 16 universal condenser and 12" fan in the front of left rear fender. Zimms and Griffiths offer these but I opted to implement basically the same thing with parts I assembled.

I'm going say fans on rear stock condenser, Griffiths front condenser and left rear front of fender condenser is a good start. I think SC's might have vent issues. 1986 was the first year of the "big vents". You should read up on that.

Maybe consider Enviro-Safe freon? People that use it love it. I personally don't have experience with it. Yet. I might be trying it on a buddies 86 Carrera in the future.
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Old 08-17-2019, 07:48 AM
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Fan switch.

Quote:
Originally Posted by Steve Marshall View Post
GH85 - That's some serious AC stress tests you've put your system through. I've not road tripped yet and I'm curious how performance will be over time.

Throughout his AC adventure I would stop in a parking lot and idle for 10 minutes to see how hot the engine got. It never exceeded 2/3's hot when the ambient was in the mid 90's. Which is about as hot as it got before I started messing with the AC. This didn't concern me at all but I decided to add a 7" fan to the oil cooler just to be safe. It's a cheap and easy upgrade. It's not connected to a thermostat it but it is wired to run only when the AC is on. I figure if I'm not not running the AC, it's not hot enough to need the extra cooling.

It's hard to tell for sure, but I'd say with the addition of the fan the temp now stays between 10 to 15 degrees below 2/3's hot.

I'm not convinced fans on the condenser are an engine heat issue. I can see in how in theory it might be? Maybe? Kinda? But in reality I'm not experiencing it. How can more airflow at idle hurt?


Over and above adding the cooler fan
(Us early '86 owners did not get one),




^^^^^
I added this front oil cooler temp switch which can be ordered at most on/off values.

Ours is:

On-215f

Off-197f

Admittedly, we very rarely get the "Texas" heat,
but on a 90f day, we hold very steady at 220f,
which help boil off the moisture in the oil.

Best,

Gerry
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Per Road and Track magazine:
Only in L.A.:
In the window of a bar in Hermosa Beach, California.
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Last edited by 86 911 Targa; 08-31-2019 at 05:45 PM..
Old 08-17-2019, 02:17 PM
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Can you post the exact part number and place to order that oil cooler fan sensor, or PM me? I have tried buying those 3-4 times, and every time the thread pitch is not right for the oil cooler.

On a side now for your A/C, be careful with those vent temps. Having 2 different trick A/C systems in 2 cars and living in a humid climate, I strongly recommend everyone have a way to monitor your evaporator temps. For short drive those 39F vent temps can be fine, but I have found evaporator freezing to be a real problem on drives over about 20 minutes here in Florida. I run my thermostats so my evaporator never gets below 33F. Yes this hurts your cooling in the short term slightly, but it means your system can keep cooling all day long. Modern cars have ways to prevent icing, like actually blowing heated air onto the evaporator periodically (my BMW does this). I hid a digital gauge in the ash tray on one car, and put the sensor not eh top of the evap. On that car one the thermostat was set for the right temp I just noted taht as the “max cold” setting.
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Old 08-20-2019, 11:03 AM
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Duc - Exactly right on too cold vent temps. The snowflake knob is the thermostat. If you remove the probe in the evaporator and stick it in a cup of crushed ice and then rotate the snowflake knob until the front condenser fan, and compressor clutch, kick off, you now know the 32 degree tick on the knob. I run my AC at one tick lower on sub 95 degree days. It's very important to re-insert the probe solidly and deep between the fins.
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Old 08-20-2019, 06:17 PM
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AC Upgrade for 1986 Carrera

I drove just last month in south Florida all the way to Key West. The humidity was insane high. I had my temperature knob set at max cold, and never had a freeze up.
I recently replaced my evaporator fan with Griffiths upgraded fan. When I had the top of the fan box off, I placed the brass tube in a good spot, and put a small dab of thermal paste on the tip of the sensor bulb.
I did not run the fan at max after the passenger compartment cooled off. I can run the temp knob at max cold for long hours of driving, until my bladder forces me to stop. 4 days of 11 hour drives and no freezes ups. And the LED on the variable speed fan control showed me the compressor was cycling off and on in 98 degree heat driving due west into the afternoon sun.
The air blowing was so cold I could not keep it blowing on my face, as it felt uncomfortably cold.
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43 Year member of the Porsche Club of America
1985 911 Carrera; 2017 Macan
1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!

Last edited by GH85Carrera; 08-20-2019 at 07:11 PM..
Old 08-20-2019, 07:08 PM
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GH85 - The way I understand the cold knob as explained by Griffiths is each tick is about two degrees warmer, more or less. I guess due to age and probe placement and possibly the evaporator efficiency not all max cold sitting settings are the same? That's why it's important to calibrate the cold knob. I assume my max cold is 30° since 1 tick back from max is where the compressor kicks out?
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Old 08-21-2019, 05:27 AM
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Quote:
Originally Posted by Steve Marshall View Post
GH85 - The way I understand the cold knob as explained by Griffiths is each tick is about two degrees warmer, more or less. I guess due to age and probe placement and possibly the evaporator efficiency not all max cold sitting settings are the same? That's why it's important to calibrate the cold knob. I assume my max cold is 30° since 1 tick back from max is where the compressor kicks out?
That is possible. My guess, and it is just my guess, it all comes down to the probe placement, and what it is in contact with. Before I moved my probe, I had to run the temp knob a 1/8 of a turn back from full cold to prevent freeze up.

Now that I have it stuck in tight against the fins of the evaporator, and the dab of thermal transfer paste on the bulb end, it works like it should. I can run the knob at full cold, and on even on a crazy hot humid day, the compressor will cycle off before it gets to the freezing point. I will admit i was surprised to see the compressor cycling on and off on a hot day, and running for 11 hours with only bladder comfort stops as a pause.

Just yesterday I drove back 20 miles from an errand in my 1986 El Camino. It was 101 degrees, and the heat index was 112. The AC is 100% stock as it came from GM. It was blowing 38 degree air and the volume of air was something my 911 can olny dream about. I got cold and I had to turn the fan speed down. I wish the Germans had hired some GM AC designers to design the AC system in the 911s of the era.
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43 Year member of the Porsche Club of America
1985 911 Carrera; 2017 Macan
1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!
Old 08-21-2019, 06:43 AM
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"I wish the Germans had hired some GM AC designers to design the AC system in the 911s of the era."

It's the hottest month of the year and the high temp today in Stuttgart is 77°. I can't imagine those German AC engineers coming even close to comprehending the kind of heat we deal with!
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Old 08-21-2019, 06:56 AM
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Quote:
Originally Posted by Steve Marshall View Post
"I wish the Germans had hired some GM AC designers to design the AC system in the 911s of the era."

It's the hottest month of the year and the high temp today in Stuttgart is 77°. I can't imagine those German AC engineers coming even close to comprehending the kind of heat we deal with!
One of the great stories that came from War Bonnet Tech sessions in Oklahoma I saw unfold first hand. As I remember it was Anatole “Tony” Lapine (the man that designed the styling on the 928) came to talk to our group. He is typical of the German, and fascinated with the American west.

After the War Bonnet Tech, he had Porsche provide him with a new 911 Carrera so he could drive Route 66, from Oklahoma to California. In the American desert he came across our typical heat and realized the AC sucked. He got back to Germany, and talked to the right bosses. They sent two of the AC designers to America to do the same trip, in a new 911. They got back and admitted, the AC really was inadequate. They knew America was the largest market. When the 964 version of the 911 hit the market, the AC worked like it should have.

So our PCA region old timers all like to think we are partially responsible for the improved AC in the 911.
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43 Year member of the Porsche Club of America
1985 911 Carrera; 2017 Macan
1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!
Old 08-21-2019, 07:34 AM
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I agree the 964 was the first 911 to have decent A/C except the evaporators they chose tended to leak.
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Old 08-21-2019, 09:17 AM
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Quote:
Originally Posted by RSTarga View Post
I agree the 964 was the first 911 to have decent A/C except the evaporators they chose tended to leak.
Some of that was the era of major cost cutting. Porsche like every manufacturer specified a part for a function, and whatever company made that condenser, did a poor job. I am not defending Porsche, as they have not done the best job of parts suppliers, even today. When I go to my local dealer, and buy a Porsche supplied coil for my 911 it will be a silver coil, made in Brazil, and 50-50 chance of it not working right from the box, and if it does work, it likely will fail in short order. My only choice for a good quality replacement coil is a OEM black coil from a salvaged car. A 30+ year old used German coil from a junk yard is better than the part they sell right now. That is sad.
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1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!
Old 08-21-2019, 09:35 AM
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Oil cooler fan switch.

Quote:
Originally Posted by Duc Hunter View Post
Can you post the exact part number and place to order that oil cooler fan sensor, or PM me? I have tried buying those 3-4 times, and every time the thread pitch is not right for the oil cooler.

On a side now for your A/C, be careful with those vent temps. Having 2 different trick A/C systems in 2 cars and living in a humid climate, I strongly recommend everyone have a way to monitor your evaporator temps. For short drive those 39F vent temps can be fine, but I have found evaporator freezing to be a real problem on drives over about 20 minutes here in Florida. I run my thermostats so my evaporator never gets below 33F. Yes this hurts your cooling in the short term slightly, but it means your system can keep cooling all day long. Modern cars have ways to prevent icing, like actually blowing heated air onto the evaporator periodically (my BMW does this). I hid a digital gauge in the ash tray on one car, and put the sensor not eh top of the evap. On that car one the thermostat was set for the right temp I just noted taht as the “max cold” setting.

https://www.google.com/search?sourceid=navclient&aq=&oq=nasson+switch&ie=UTF-8&rlz=1T4GUEA_enUS570US570&q=nason+switches&gs_l=hp..0.0i22i10i30l2.0.0.0.18327...........0.sD wkGMsQBfc#spf=1566410139000
^^^^^
Here is the Nasson web site.

0020-Oil-Nasson Oil Cooler Temperature Switch-TT-E3A-197RQCGG
^^^^^
Part number.
Best,

Gerry
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1986 911 Targa.
Per Road and Track magazine:
Only in L.A.:
In the window of a bar in Hermosa Beach, California.
"Happy Hour prices during all car chases."
Old 08-21-2019, 10:01 AM
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A/c

Quote:
Originally Posted by Steve Marshall View Post
"I wish the Germans had hired some GM AC designers to design the AC system in the 911s of the era."

It's the hottest month of the year and the high temp today in Stuttgart is 77°. I can't imagine those German AC engineers coming even close to comprehending the kind of heat we deal with!
Hi Steve,

I have been to Texas a few times,
and, "felt the heat".

Just looking back at the early 911 & A/C history.

During one of our factory visits, we met at Weissach with the-then late
Porsche CEO Peter Schutz who made it very clear to all present that initially
Porsche had no intention to install A/C in the 911 model.

However, after the 70% U.S. market insisted, Porsche acquiesced.

It is obvious to many that the 911 due t0 the rear engine configuration,
was not a strong A/C candidate.

However, as time passed another condenser was added, aftermarket
items became available increasing A/C performance.

Thus, comparing 911 A/C to any front engine U.S. car is not a fair test
primarily due to the A/C component location.

Having currently refurbished our entire A/C here are the results:

1. Replaced all hoses.

2. New compressor.

3. Flushed both condensers.

4. Replaced evaporator.

5. Replaced the temperature switch.

6. Transitioned from R-12 to R-134.

On a 90f day about 80% humidity, freeway driving, the hysteresis
is:

52f-compressor on.

42f-Compressor off.

With the temp switch set at the #3,
and, the fan one step down from the highest speed.

These settings seem to be "the happy place" thus
preventing evaporator freeze-up.

Pm me as needed.

Best,

Gerry

By the way, member kuehl is your best contact
He's been there & done it all.
__________________
1986 911 Targa.
Per Road and Track magazine:
Only in L.A.:
In the window of a bar in Hermosa Beach, California.
"Happy Hour prices during all car chases."

Last edited by 86 911 Targa; 08-21-2019 at 04:00 PM..
Old 08-21-2019, 10:29 AM
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GH85 and Targa - Great stories on the history of our underperforming AC systems.

Well, I had a new hose failure. All the R134 leaked out by the following weekend. Sooo... I thought I would refill with EnviroSafe Industrial. What the hell? People that run it seem to love it.

Apparently there is two types. Regular and Industrial. They claim Industrial get's you 5° cooler. It's $ 6 per can and one 6 ounce can = 16oz of R134. They kill you on the freight. In fact it's about the same $$ as the freon.

I figured using 39oz of R134 = 14.6oz of Envirosafe. I ended up putting in 16.9oz by misjudging how much I put in. But I went with it.

The results were pretty impressive. The ambient was about 98° and just baking. Pressures were 44/210 which is much lower on the high side. I did my test run into town and was 3.5° colder than the coldest result in the same conditions with R134.

I drove back to Austin in the same heat but got greedy and set it to the coldest setting. As soon I saw 39 on the temp gauge the evaporator froze up and we were at 60 for the rest of the ride home. Next day, I drove about an hour in 90° heat and the snowflake nob set at 6 (out of 8) and the vent temp ranged between 42 and 46 cycling with the compressor down the highway. It would creep to 49 at stop lights.

My conclusion is Envirofreeze works, and 42 is the lowest vent temp I can run without freezing up the evaporator. I'm curious if anyone is running a stock system, with just hose replacement, with EnviroSafe or RedTek and getting satisfactory results?
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Old 08-31-2019, 01:22 PM
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Steve, just noticed you put a 12 X 16 condenser in front of the wheel. I did not realize you could get one in there that large. I may try to relocate my 12 X 12 condenser there. It’s currently behind the wheel but that’s really close to the exhaust.
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Old 09-01-2019, 06:04 AM
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