a/c questions

[Dkennel]

I bought my 87 Carrera last fall. Car is great, big issue for me is though the non-functioning a/c. Car was retrofitted in Denver for R-134, records show that it would need to be recharged quite frequently, would blow cool for a couple of weeks and then quit. Last service record indicated a leak in one of the hoses (not sure exactly where). I have considered replacing and upgrading the a/c, looked at Kuehl, Rennline, etc...
Local Porsche club people and one (non-Porsche) shop recommended just re-charging system, leak test with UV and replace leaking hose(s) only. Seems like a less cost intensive approach, but what do you guys think? Should I go ahead and at least replace all the hoses? Do I replace with barrier hoses?
Right now nothing works, would recharging re-activate the system if all I have is a leak? I just don't know too much about a/c in general. Some people recommend DIY others say absolutely stay away from it if you are not experienced.
I'd like to get this taken care of BEFORE spring and summer is here.

Thanks!

[Dkennel]

I meant rennaire of course...
Can anybody recommend an a/c shop in Texas (Dallas or West Texas)?

[tonythetarga]

it is more than likely the compressor. Look up...under the rear deck lid where the compressor is. Do you see a thin black line "sprayed" on the lid from left to right?? If you do that is a bad compressor. You might need hoses as well, if they are leaking for sure, but the compressor is the weak spot. While you are at it, you should buy a new dryer bottle in the front left fender and replace that. When gunk builds up in there it is a good idea to start fresh with a clean bottle, especially after 17 years of service.

[Dkennel]

There is a black spot, not a thin line sprayed...

[tonythetarga]

If it is oily, it is probably oil from the compressor. That seal failure is the cause of the leaking refrigerant. There have been threads on this problem and you should search for more info. There are tips on rebuilding the compressor or improving the system completely with a new one. To just recharge your current system is a waste of good money after bad.

[Gordo2]

Having torn the complete A/C system out of my car I can safely say there are a lot of potential places for leaks/failures. I recommend finding the leak first and then determining what you want to replace. Could get expensive replacing lines etc. only to find that your leak was not repaired and caused by a high dollar component (like an evaporator or condenser).

Good luck, Gordo

[Dkennel]

if I understand right though I would need to recharge the system first to actually find my leaks???
No way of really figuring out what's wrong without doing that first...

[Jim Sims]

No, one can evacuate and listen for inward leaks (air into vacuum) using an ultrasonic leak detector. An alternative is to open a fitting and attach an ultrasonic sound generator at the opening and listen for the sound leaking out elsewhere in the system - the hoses and internal passageways act like waveguides for the sound but any leak produces an emission of sound which can be heard using the detector. Cheers, Jim Sims

[Gordo2]

If your system already has a low charge you should be able to fill it with R-134 that has a dye to help locate leaks. No need to evacuate/recharge or at least on the few systems I have worked on (A/C isn't one of my stronger areas, but I have repaired a few systems with leaks before).

I've tried the florescent stuff with the glasses that are supposed to make the dye glow. I wasn't impressed, the cheaper dye stuff worked better.

Again there are loads of places where it can leak. Get familiar with where everything is and get a good visual on the lines etc. prior to recharging with the dye. You may get lucky and find the leak while you are at it.

I found that the receiver/dryer on mine had rusted out on the backside of the hose clamp that holds it in the driver's side wheel well. I found it because I was removing the whole system; not sure how hard it would have been to find if I were troubleshooting.

Keep in mind, if you open the system up by removing any of the lines you will want to run a deep vacuum on the system after you close it up to get all of the moisture out. Water from humidity in the air will result in water in your lines which will ultimately kill an A/C system.

Gordo

[bigchillcar]

dietmar,
jim sims is the a/c man..do a search on his name and you'll find tons of threads on a/c info...fyi.
ryan

[rfuerst911sc]

You have to repair / replace anything that's leaking and to find the leaks the best way is probably recharging the system with R134A and the leak detector dye. Once you have determined the leak / leaks source then you have to figure out what to do. When I repaired mine I knew I was going to replace all the hoses with barrier hose, I pulled all the old hose myself, cut off the old connections and had a local shop make new hoses for me this is a cost effective way to replace the hoses. While the system is apart you need to replace the receiver/drier, you can go with a factory or aftermarket replacement or there is a unit called a Procooler which many people say it improves the cooling ability of the system. I'm not sure if your car has o-ring fittings but if it does make sure you replace all o-rings with new. If your car has flare fittings you might want to consider adding o-ring style fittings, if not then consider useing copper flare sealing washers as flare fittings can sometimes be stubborn to reseal when used over and over. Keep in mind that R134A has a smaller molecule structure than R12 so it will leak easier and some folks say it doesn't cool as well. Educate yourself if you plan on doing it yourself, it can be done but must be done correctly and there are some special tools needed-vacuum pump,manifold gauges etc. to do the job right. I live in Florida and I am proof that a older car ( 83SC in my case ) can have effective AC if done right. Good luck.

[bigchillcar]

if you plan on keeping the car for a while and driving in summer heat, i'd definitely replace all hoses with barrier-style, especially owing to the smaller molecule issue that rfuerst brought up. new receiver driers from napa can be purchased cheaply and would be another good idea. also, the condenser(s) require airflow across them in order to function..make sure that your fan(s) are working. do you know where your condenser(s) are? decklid or in the front fender mounts?
ryan

[Dkennel]

I think it is in the decklid and under the front end(?). Should I use rennaire hoses? Somebody mentioned local a/c shops can make hoses (?!?!?). Is there any way to test the compressor without charging the system??


Dietmar

[Dkennel]

rfuerst: what changes have you made to your a/c? Only new hoses, receiver/dryer, otherwise stock?

[bigchillcar]

google a search on 'sidewinder' and fans for info on a low profile fan that can be fitted to your rear deck condenser for better cooling during 'stop and go' traffic situations..as most with a/c know, it tends to blow cooler while moving. you can buy barrier hose from a company like rennaire, complete replacement set for around $350-400 or you can buy bulk barrier hose, acquire the proper fittings and have a local a/c shop make your own for closer to $150..just more legwork involved, but if you have the time it would be the way to go..if you ain't a diy guy, go with the rennaire product. the procooler is an alternative to the stock receiver/drier, but i think the jury's still out on whether it makes a noticeable improvement..some say yes, others no..so for me, i'd just get a stock replacement r/d..but if $$ is no object for you, i'd say you havenothing to lose with a procooler. do a search on this board for 'subcooler'..something jim sims came up with that he runs in his ans and his son's car (both, right, jim?). in my opinion, new hoses, new r/d, evacuate and start with fresh oil and refrigerant, adequate airflow over your condenser(s) (the more the better) and that's about as good as it gets. it will never blow like a contemporary front-engined car. reason? they use maybe a couple feet of hose..our rear-engined cars use maybe 30 feet! in other words, it ain't easy to design a good a/c system for a rear-engined, air-cooled car. the laws of physics (cooling loss) are what limit you. you can be made 'comfortable', although that is subjective, but probably won't ever complain of 'freezing' inside your car no matter you do to the a/c system. this subject has been analyzed and debated from this side to sunday..no one has ever come up with an amazing solution..and what solutions we do come up with generally come with a price..
ryan

[Jim Sims]

The 87 carrera A/C system will have o-ring fittings. The Rennaire hose kit is a reasonable price; I note it is on sale at $370. It is made of the reduced size barrier hose which is easier to install (and lighter) but it does have both fittings already on each end of each section of hose which makes it a little more difficult to install - stuffing a 90 degree fitting through a tight space is always a pain. There is nothing special about the hose or fittings used in the Rennaire system; it's advantage is it is already made (provided the lengths are correct and the fittings are on in the correct orientation) .

A/C shops may or may not be able to make or repair hoses; it depends on their equipment and philosophy (some are merely parts swappers). A "bubble crimp" A/C hose fitting swaging rig costs between $500 and $2000.

A shop could likely rig up a stand alone compressor test rig but it wouldn't be cost effective (labor is expensive); given the age of you car it may just make more sense to buy a new or rebuilt compressor. If you are the DIY type you could replace the shaft seal and install new oil in your current compressor and then pump down your system.

You may want to look into the aftermarket dash A/C vent options; one of the problems with OEM Porsche A/C is the poor air distribution out the vents.

Cheers, Jim

[rfuerst911sc]

Dkennel I pulled every item out of my car except the compressor,cleaned up the evaporator and the evap. fan assy,oiled the fan motor then removed the rear decklid condensor and added a rear quarter panel condensor with fan and a huge underbelly condensor plus kept the OEM front fan assisted condensor. I went this route for a couple of reasons but the main reason was to clean up the engine compartment by removing the rear condensor. If I had to do it all over again I would have added the Procooler in place of the receiver/drier but I can add that in the future. I also used HC12 refrigerant which is a drop in R12 replacement because it is friendly with the R12 oil, however the refrigerant is flammable and that turns off some people but it works great for me.

[911pcars]

Notwithstanding the $2000 solutions, your basic questions was "where does it leak"?

Install a small quantity of HC134a into the system (DIY or shop). This should be enough to detect the leak source, then locate an A/C shop with an A/C sniffer - more sensitve to leaks than dyes. Dyes also displace the volume inside the system that would ordinarily be filled with refrigerant. Installing more or less refrigerant than the system is designed for does not an efficient system make, and you want to make the borderline Porsche A/C system as efficient as you can. Dyes are only observable with a black light. There's a change the leaking dye could stain some interior fabrics and even clothes - you'll not win any dancing contests at your local disco with dye-stained threads. :-)

Back to subject: Once located, replace the part, be it hoses, O-rings, etc.

As others have said, the compressor could have a leaking seal. If otherwise functioning, no need to replace it other than to replace the seal or to update to a more efficient unit like a Sanden or equivalent.

If there's a chance you'll be consulting with a pro shop in the near future, I'd suggest staying with the standard R-12 or HC-134a refrigerants. When you use propane, butane and other exotic blends of alternate chemicals, this prompts most A/C shops to excuse themselves from mating their recycling and inspection machines with your system for fear of contamination.

Sherwood

[bigchillcar]

most A/C shops to excuse themselves from mating their recycling and inspection machines with your system for fear of contamination.

lol...sherwood, i don't doubt this for a second in cali..but in arkansas, these 'fears' simply don't exist! you see, we still can't pronouce '****aminashun'..or really spell it that akritly..
ryan

[scottb]

Originally posted by 911pcars
As others have said, the compressor could have a leaking seal. If otherwise functioning, no need to replace it other than to replace the seal or to update to a more efficient unit like a Sanden or equivalent.

Has anyone seen empircal data as to whether the Sanden is actually more efficient than a properly functioning Nippondenso? The reason I ask is that I once spoke with someone about replacing my Nippondenso, and though he sold Sanden he candidly said that in his opinion they weren't appreciably better than the ND.

One misconception is that the Sanden is a rotary compressor. It isn't -- it's a wobble-plate/piston configuration. My understanding is that the Seiko-Seiki is the only true rotary, and that they are more efficient than the piston compressors.

Scott