bmoe

I am still on R12 and my AC works some. I may check the charge but
I have seen upgrade ads from Griffiths/RennAire/RetroAIr.
How hard is it to DIY? Can anyone send me instructions so I can see if I can do it? Bentley manual dose not give much info.
Anyone near Dallas-Fort Worth that could give advice/ help?
Thanks

griffiths

Upgrading your AC system, for example:
1) New barrier hoses, driers, o-rings and pressure switch.
2) Inspecting compressor internals, condensers, evaporator, evap motor, testing
thermostat.
3) Upgrading evaporator and adding condensers.
4) Removal of old parts, installation of new, reading detailed installation instructions.
5) Evacuation, charge & test.
6) Putting away your tools.
For a Texas car, 20-25 hours; patient hours of fun. Best if spouse and kids sent on a vacation, leave dog and cat with neighbor.

Tools & Equipment
A lift is not necessary however it helps with a few things, again not necessary.
1) 4 jack stands.
2) floor jack
3) Common metric and inch wrenches, socket set, screw driver, drop light.
4) Shop vac; dirt tends to accumulate under the ac hoses and drop down.
5) Safety glasses (keeps dirt out of eyes), Rangers baseball cap.
6) two large cookie sheets, to toss nuts and bolts, and tools on.
7) Couple of six packs of Shiner Bock or Becks.
8) Solid stool to sit for enjoying above.

How Difficult?
1) On a scale of 1 to 10, where 1 is changing a wiper blade, 5 is compounding and waxing the paint, 10 is an engine drop with complete tear down and rebuild....... this will be 7 because of the time and distance covered (front to back of car). To replaces hoses alone is 8 hours.
Reading the instructions (if you purchase from a company that supplies them) will be 2 hours; you will be reading twice.
2) Besides detailed instructions to save you time and pondering, having available technical support (phone, email, etc) is like having a good spare tire.
3) You can do this job in your driveway if necessary however having a garage can be helpful on hot or rainy days.

What to Buy?
1) There is no 'magic bullet inexpensive' solution. Expense is simply
your own personal measure. For example: a used Carrera $18,000,
engine rebuild $13,000, tranny overhaul $5,000, good paint job $7,000,
new tires $800, stereo upgrade $600. Having a reliable and Texas worthy AC system..... priceless.
2) How much performance to buy? I tend to look at this like planning a family and building a house; better to plan for and buy more house rather than wish you had more when you need it. Again, you can look at this as a personal choice.
3) There are 3 primary AC aftermarket companies: in alphabetical order they are Griffiths, Rennaire and Retroaire. Each company has its own approach in product design, but the basics are "integrity" first and performance second. Integrity requires new barrier hoses, o-rings, drier, addition of a binary pressure switch, in your case since the car is between the years of 1986-1989 you will want to replace the factory evaporator since the design tends to leak. You will need more condenser capacity, here again each company takes it different approach.
4) Compressor wise you would be wise to stick with the factory selected
Nippondenso 10P15C compressor rather than trying to convert over to a smaller capacity Sanden; the factory selected Nippondenso compressor is a bolt-on no modifications factory original look and design. A Sanden can power the system however not necessary, nothing to gain in terms of performance or reliability; if you had a SC with a York compressor then you would consider a Sanden. Feel free to ask how to inspect your current Nippon.


How to best consider your investment in time and money:
1) If you don't drive this car often, its a garage queen that comes out on moderate sunny days, you will still need to spend 15-20 hours of labor.
Money wise, again, each company has its own approach.
2) If you prefer to take the car out as often as possible in the warm to hot season, you prefer the car dies before you do (after all, why did you buy a Porsche; to drive it), you will be looking at 20-25 hours and spending a bit more to do it right and do it once.

Suggest reading:
A) This thread on Pelican walks through product installs and some product comparisons
AC Upgrades
B) This link can provide you some good basics to understand the system
The Mr. Ice Project

bmoe

Does anyone have a copy of instructions I could read? Any DFW people out there?
Any shops near DFW that have done excellent work?

wwest

The single major shortcoming of your 87's factory A/C system is the lack of adequate refrigerant condensing efficiency when the engine is operated mostly in the low RPM ranges for extended periods.

The secondary problem is the "designed in" refrigerant leakage aspect of the non-barrier hoses used with R-12 refrigerant, exacerbated by the propensity of the system to pressurize the system beyond the design capability. Read your owners manual. The factory system has the ability to provide "excessive" liquid refrigerant flow for the TXV with a FULL heat load in moderate climates, conditions in which you might choose rolling down the windows rather than use the A/C.

The compressor does not cycle off in these conditions even thought the R/D might become over-filled with liquid refrigerant. The compressor is controlled ONLY by the thermostatic setting, which in the above case would be set for maximum cooling, compressor shut off only if/when the evaporator core declines to freezing or slightly below.

In that circumstance one can easily see why the R-12 would be forced out the pores of the non-barrier hoses used back then.


Bottom line: You can spend $200-$500 and get A/C performance that is perfectly adequate for HOT & HUMID Augusts in your area.

Or...

You can spend upwards of $5000 and get performance that is less adequate than the $200-500 purchase.

For about $200-300 you can have a certified A/C shop/technician (NOT a Porsche shop) convert your system to R-134a, including a new R/D and a trinary pressure switch.

For another $200-300 you can have the system pictured below.

3rd element of the trinary switch can be used to switch power to the fans in the pictures anytime the engine fan airflow is not adequately cooling the engine lid condenser. This, trinary pressure switch, the method the factory used in the 993/994 series to control the condenser cooling fans/blowers.

PelicanParts.com

The Porsche 911 has never been renowned for its air conditioning systems. I'd recommend taking a look at our A/C tech article to give you some insight on the A/C system in your Porsche. Hope this helps!

http://www.pelicanparts.com/techarti...AC_Systems.htm

-Luccia

rstarga

It's all about the condensors. The ultimate fix is to use a 964 front condenser and fan like this.

wwest

Yes, agreed, ULTIMATE..!!!

More refrigerant condensing capability...

But moving more cooling air over the rear lid condenser at only times of need accomplishes the same task at a much lower cost and complexity.

wwest

One other note:

If you should go with the ULTIMATE, fender mounted condenser/fan, I would suggest eliminating he front lip condenser and fan/blower. The front lip condenser's fan makes more noise and draws more power than the meager results justify.

The link below is to the BEST of the aftermarket fender/wheelwell mounted condenser/fan upgrades.

Half the cost of the Griffiths/Kuehl condenser/fan and not subject to degraded performance due to radiant heating from the nearby >1000dF catalytic converter. This is especially a problem "after-run", post engine shutdown, wherein that additional(***) radiant heat will most certainly BOIL any liquid refrigerant in the nearby condenser, quite possibly raising the A/C system temperatures/pressures well above system component design specification.

*** In addition to the radiant and convection heat raising from the engine/exhaust heating the rear lid condenser. Some systems prevent component damage from this effect via incorporating a ~450 PSI HPRV to "vent" excessive high side pressures back to the suction side.

http://www.allzim.com/store/cart.php..._detail&p=1240

rstarga

If you use a stock 964 front condenser, thats the only one you'll need. You can eliminate the one over the engine too.
If you decide on the rear unit from an aftermarket supplier, the best quality and instructions, support come from Griffiths, but you pay a bit more. How much is your time worth?

bmoe

So I take it nobody has an instruction booklet left over from a total install?
WWest- so I could change to 134 and put in a high/low pressure switch and a new receiver drier and do fine? Keep the old hoses and just refill the 134 yearly?For extra money put fans on the rear condenser? Are they 964 fans or aftermarket ones?
RStarga do you use a stock 964 front condenser for the front L wheelwell? Did you bypass the front condenser.? Are you near DFW?
What percentage of condenser capacity is in the front? If say 30% then improving it say 40% would help. If only 15% the any improvement may not count much =6%. Does a powerful fan in the front make a diff?
Do people put Zims or Griffiths condenser in the front wheelwell or just the 964? The cat has a heatshield but it is still close to the wheelwell.

wwest

The 964/993 series does not have a rear lid condenser yet they both have provisions for "after-run" engine/exhaust cooldown period. Those will run the cabin heat blower for up to 15 minutes as an aid to cooling the exhaust manifold.

So anyone who says the radiant heat from the catalyst isn't a factor in cars with after-run heating of the rear lid condenser probably haven't thought things through.

Also, I was able to disconnect the power from the front condenser blower. If you need the front blower it might wise to mount a thermostatic switch in the place provided on the R/D as was done on the 944 and 928 so the front condenser fan only runs when cooling from forward motion doesn't suffice.

rstarga

west is correct no aftermarket guys do the 964 setup because only cars with no battery boxes can use it. So from about 74 up. It will be your only condenser, so it will be 100% of your condensing capacity. It is up front away from all heat sources. It does require some installation ingenuity and doing your hoses.
The 964 condensor is about the same size as the Griffiths rear fender unit, but it is away from the heat. I think he sticks with the above engine condenser, so you can see that the front unit is more efficient. The 964 fan on it is well integrated.

If you are in Dallas Mayo Performance would be more than capable to do the installation.

wwest

Most factory systems operate satisfactorily when cruising, engine operating well above idle provides enough cooling airflow for the rear lid condenser, and roadspeed airflow cools the front lip condenser.

So what's missing...??

Condenser cooling airflow at low speeds with engine mostly idle.

HiWind

Hi Guys

great info here thanks - a friend asked me a question and I wasn't sure ...
can you just add the compressor and condensor from a 964 to a 86 carrera to make an improvement to cooling?

thanks
Matt

griffiths

Swapping a compressor from a 964/993 to a earlier Carrera or SC is not an improvement.

Upgrading your AC system, for example:
1) New barrier hoses, driers, o-rings and pressure switch.
2) Inspecting compressor internals, condensers, evaporator, evap motor, testing
thermostat.
3) Upgrading evaporator and adding condensers.
4) Removal of old parts, installation of new, reading detailed installation instructions.
5) Evacuation, charge & test.
6) Putting away your tools.