Basic AC Question

[whiterabbit]

So my 3.2 is 99% stock including AC hoses/system and ideally I want to keep it that way. The car is still R12 and low on freon so can people please assist with my options considering the above. The system I have is still fully functional just getting weaker over the past couple of years.

Option 1: Can I just get a shop to refill with R12 and repeat every few years?

Option 2: Can I get an R134 conversion and still keep the car looking stock? Can I do this my self with the kits in local parts store.

Option 3: Can I do minimal changes to make the AC better while still looking stock?

[RedCoupe]

Go to Griffiths web site where there is a wealth of information about the 911 a/c system. They also sell quality upgrade kits and parts. The bottom line is that if you do a 134a conversion without replacing all the old rubber hoses, you're not going to be happy because your new refrigerant won't stay in the system very long.

[Bob Kontak]

Option A would be the most economical if the system holds refrigerant.

[nickyclyde]

I've kept the r-12 system in my daily driver VW Vanagon . Charge it every 3 years ,ice cold. More places have R-12 now than 4 years ago. Not every shop ,but a lot of the good one keep some. My 930 is r134 and works well also. I'd go with option 1

[porschenut]

Originally Posted by nickyclyde

More places have R-12 now than 4 years ago. Not every shop ,but a lot of the good one keep some.

Really? R-12 was outlawed years ago, so I would think the supplies are just about history by now. How can more shops have it today than before? Where are they sourcing it?

[emac]

You can buy it but you need to own a gold mine, and be certified by the EPA
Ernie 81sc

[wwest]

Originally Posted by whiterabbit

So my 3.2 is 99% stock including AC hoses/system and ideally I want to keep it that way. The car is still R12 and low on freon so can people please assist with my options considering the above. The system I have is still fully functional just getting weaker over the past couple of years.

Option 1: Can I just get a shop to refill with R12 and repeat every few years?

Option 2: Can I get an R134 conversion and still keep the car looking stock? Can I do this my self with the kits in local parts store.

Option 3: Can I do minimal changes to make the AC better while still looking stock?

I had my 88 Carrera converted to R134a for about $200.00

For an extra $50 or so you could add a RED DOT trinary pressure switch to add override control capability to the compressor clutch and have 3a 3rd function to control the cabin heater fan when/if the overall heat load for the condenser and engine gets to high in stop and go conditions.

[Bob Kontak]

Originally Posted by emac

You can buy it but you need to own a gold mine, and be certified by the EPA

+1 on gold mine.

You can buy R12 on EBAY if you state to the seller you are only buying it for reselling.

You can buy if you obtain a license/certificate from the Mobile Air Conditioning Society - online test - EPA 609. You can then buy and put R12 in but you can't take it out.

If you actually want to work on R12 systems for real, you have to suck it up and have the EPA test you AND your equipment.

[Arne2]

I did a relatively complete refresh, including the hoses. (See ['84 Carrera] A/C re-work for mild climate ) My car's hoses bled the R12 out in a matter of months, even if I didn't use the A/C at all.

I replaced hoses, and upgraded the evaporator and front condenser. Still looks stock, as the hoses are the only visible part I replaced. Now running R134a, still blows cold after not being used all winter. (Just tested it a couple of days ago.)

[kuehl]

Originally Posted by whiterabbit

So my 3.2 is 99% stock including AC hoses/system and ideally I want to keep it that way. The car is still R12 and low on freon so can people please assist with my options considering the above. The system I have is still fully functional just getting weaker over the past couple of years.

Option 1: Can I just get a shop to refill with R12 and repeat every few years?

Option 2: Can I get an R134 conversion and still keep the car looking stock? Can I do this my self with the kits in local parts store.

Option 3: Can I do minimal changes to make the AC better while still looking stock?

Before you place a value or score on the options you have so far selected, and attempt to compare them to other cars or experiences, you have to compare apples to apples. A 911/930 driven in Atlanta requires more ac wise than the same vehicle driven in Portland, ME or San Francisco. Alike, a driver that has a passenger or a driver that needs or enjoys more ac is much different than one that is happy to just get buy.

Whether you are running R12, R134a or an alternative EPA approved or outlawed refrigerant, there are a few "needed" things regardless of which you decide on. R12 is still legal, still available but costs more per pound than alternatives. R134a will be readily available for quite awhile, and it works in a 911/930 up to a certain ambient outside temperature. However, whether its R12 or R134a the overall performance of the system is not as good as front engine vehicles due to condenser performance, lack of vents, and the massive glass area and lack of insulation requires upgrades if your climate area and personal cooling needs are typical.

In answer to your present 3 options:

"Option 1: Can I just get a shop to refill with R12 and repeat every few years?
Yes. To a point. Sooner or later you will accumulate non-refrigerant ambient gases (outside air) as well as moisture in the system. The ambient gases mixed with the refrigerant gas reduces the performance of the system. Moisture will cause corrosion inside the compressor and can cause blockages as well, all which results in damage to system components and increased costs. The drier helps to trap the moisture and contaminants but driers only last so long. By now your original o-ring's durometer has increased (hardened) and tend to cause leaks. A stock 911/930 has nearly 40 feet of old fashion hose which permeates refrigerant constantly, and the more the system is used the higher the permeation rate is..... If you hear stories about someone's 1980 Honda or 1990 Ford F150 not requiring refrigerant refills or top offs that often it is factually because they have about 10 feet tops of old fashion refrigerant hose or a combination of old fashion refrigerant hose and aluminum tubing.... hence less permeation leakage rates. This is why most savvy 911/930 owners sooner or later replace all the hoses.

"Option 2: Can I get an R134 conversion and still keep the car looking stock? Can I do this my self with the kits in local parts store."
Yes on stock appearance more or less. A typical R134a conversion would entail changing all the o-rings to a Hydrogenated Nitrile Butadiene Rubber (HNBR) type (colors vary in with this elastomer however green is predominant, you can get blue or black as well). A new drier is required having the proper desiccant, XH-7 or XH-9 desiccant. A binary low-high pressure switch should be added to the system. The low side cut out prevents the compressor from operating should the system pressures drop significantly (from leaks); without sufficient refrigerant/oil flow the compressor parts will not get lubricated and will wear out quickly. The high side cut out prevents the compressor from operating should the system pressures exceed 'normal' system values; excessive pressures will blow out a compressor nose seal or cause leakages elsewhere. A set of R134a service port adapters attaches to the existing R12 service ports; adapters having their own schrader valve are preferred. Either Ester or PAG oil is used to replace the old mineral oil. If you are using PAG you should use a dedicated ac liquid flush solution to flush out the old R12 mineral oil so the two don't congeal; flushing the two condensers, all the hoses, removing the TEV from the evaporator and flushing the evaporator, you don't flush compressors. If you are using Ester oil it has the benefit of blending in with the existing mineral oil, hence you don't have to spend a day flushing the system. A conversion sticker is placed in the engine compartment noting when the conversion was done, by whom, and what amount of refrigerant was used and what type of oil and qty; this is critical because if a service facility needs to work on your system, or if a new owner takes charge of the vehicle, they have to know what is in there. So,that is the basic conversion; installing new barrier hoses is wise. In terms of appearance, you will not be able to see the new refrigerant, oil or o-rings. You might notice the R134a service valves on the compressor, the binary pressure switch, and conversion sticker when you open the engine lid; new barrier hoses are black and the new fittings have a slightly different crimp on their ferrule. If you are concerned about appearance for a Concours d'Elegance car show event then you should discuss this with the officials. In terms of resale, chances are the new owner will be pleased you did the work and saved them the time.
The issue with obtaining what you need at a local brick and mortar auto parts retailer is you typically get generic what-you-pay-for items (lacking instructions specific to a 911), and it all depends upon where you shop. For example: you need so many numbers of so many o-ring sizes. Or the R134a service port adapters may be the less expensive design that uses a pin to push in the existing schrader valve in the old R12 service port; these tend to hang up and can leak. You will need at least 50+ ounces of R134a to do the job (includes enough to purge the service hoses and fill the system). Retailers typically sell 12 oz cans or 18 oz cans (you do the math). Some cans already have refrigerant oil in them, what type is in the can and how much? You need 6 fluid oz of refrigerant oil. Are you going to liquid flush the system (what oil did you decide upon?). The system needs to be properly evacuated to remove the old refrigerant (if there is any), ambient gases and moisture. This requires an ac vacuum pump and service gauge and hose set plus the learning curve (what's your time worth and do you have the patience, is this a one time job?). You can do most of the conversion work (labor with parts less refrigerant) but sometimes it is simply logical to have an experience 911/930 shop (or buddy) do the evacuation, charge and testing; you buy the components such as R134a conversion kit from a reputable Porsche source..

"Option 3: Can I do minimal changes to make the AC better while still looking stock?"
Yes. But this is where hindsight comes in; reading the forum threads and doing your research. It will all come down to this..... What do you enjoy in life? Do you enjoy driving your 911 as much as possible during the warm/hot months. Or, is the car a garage queen or weekend warrior? Do you view your monetary investments in this car as something for you, or do you consider those investments to be something you might re-coupe when you sell. Some clients contact us and say they want to keep the car stock for resale value. Frankly if money/investment is your main goal I'd suggest any of the Morningstar 5 star mutual funds vs. investing in automobiles.

If your ac requirements are not that great, you are happy driving around in a stock system, then the R134a conversion protocol discussed may work for you.

But in terms of the average 911/930 owner driving their car often during the warm season in the Atlanta area, a simple R134a conversion or keeping the system stock with R12 does not cut it (just read the 100's of threads here on Pelican or Rennlist). You will want system 'integrity' (reliable with no leaks) which means in addition to the basic R134a conversion discussed above, you will need barrier hoses. If your car is a 86+ your old evaporator (due its design) will leak sooner or later so you will want to consider a new more effective serpentine design (which is not visible because its under the front lid, under the Smuggler's box lid, in a box). If you want to lower vent temperatures, because you need as much effective cooling as you can get due to the large glass area and lack of insulation in the cockpit, you will want to consider additional condensers (such as a fender condenser; which is not really visible). You will have to review your compressor's present condition; it might be time for a new one or maybe just a re-seal. If your front condenser motor does not have a dedicated inline fuse, you will want to splice in a 7.5 amp; when these motors overheat and fry they melt down the entire blower assembly. Depending upon if you have electric seats and the year of your car, you might want to move the primary AC fuse in the front panel to its own dedicated tap because when the electric seat switch/motors start popping the AC fuse you won't have AC.

Unfortunately the AC system design and necessary repairs involved in these cars is not as simple as a set of brake pads, alternator or starter R&R. The "system" is its own unique entity. But once you learn about it and understand it, it is really easy to deal with and can be enjoyable.

If you are concerned about resale value or authenticity later, chances are the prospective buyer will be more than happy you did the job right the first time.

[whiterabbit]

Kuehl, thanks for the lengthy response.

Funnily enough the reason I want to keep stock is I was thinking of entering the car into concours as some stage for fun. Good idea about asig the judges about this. It is a garage queen that only gets driven the odd weekend in the summer with me wearing shorts. In Atlanta I prefer this time of the year and the fall to drive it most anyway. In terms of expectations I drove my other 3.2 with no AC in Atlanta and it was OK as long as it was parked in the garage or shade between trips.

I will probably give you a ring at some stage and figure out a basic upgrade to without deviating too much from stock. As stated I am not expecting fantastic A/C just OK will do

[kuehl]

If you are considering a PCA event and your in the Zone 3, PST, Peachtree, you could contact your zone Official and ask the 'rules'. If you are simply looking at Peoples Choice Awards.... anything goes!

[ganun]

FWIW. Just fair or something like that does not work because you're on the border line of having to roll down the windows and uncomfortable either way. IMO, if you want a/c then its gotta be cold. I was just thinking about it this weekend during a short trip in my 87 .
I would like if KUEHL could give some hi and lo side pressures , if I remember I put a little over a can (12 oz can) in my converted system, I don't see 50 oz going in there.

[mark waller]

Just had my 83sc in for a smog check. The shop that works on my car does have R12. $95.00 a pound and it takes about 2.5 pounds. To check the system for leaks, parts, refill he was quoting about $500.

[kuehl]

Originally Posted by ganun

if I remember I put a little over a can (12 oz can) in my converted system, I don't see 50 oz going in there.

1) If you mean you could only get 12 oz into an empty stock 911/930 system and not more, then the issue might be you did not properly evacuate the system; you did not remove all the ambient gases (air) from the system or your charging hoses before your charged the system with refrigerant. And, as well, an evacuated system that is sitting in, say, 70F ambient air, will only take about 12 oz of refrigerant (using a 'cold' can-same temperature, of refrigerant) with the compressor off (hence is why a professional charging system would charge via a liquid method with a heated cylinder).
You don't need a P&T chart to figure that out; review your evacuation and charging procedures.

2) If a stock system previously used 48 oz of R12, then it will typically use 85% nominal of R134a. So in theory, you will need 38 ounces +/- x ounces for the system. During the procedure you will need to purge the service hoses you use to put refrigerant in the system. Common service hose inner diameter is 1/4" and can range from 4 to 5 feet. The volume of refrigerant needed to purge using liquid refrigerant is about .33 oz per linear foot. Purging 10 linear feet of hose, and your gauge manifold, will take about 3 to 4 ounces in a perfect world; if you do it perfectly. If you want to perfectly charge 38 ounces of refrigerant you would then need 41 to 42 ounces of refrigerant in total; if you do it perfectly. That would mean either (4) 12 oz cans or (3) 16 oz cans. But..... for most DIY using small cans "things" happen, such as a bad tapping of a can leads to refrigerant losses. If you are charging with a 30 pounder and a scale you can monitor the process and avoid losses.

[ganun]

Thanks Kuehl, but could you give us some psi numbers for a properly operating system, ????

[aschen]

I bought the basic update kit from Kuel, it seems to be working well for me so far. We havent had any 95 degree days yet. I am not that worried about it though as I dont need fantastic air for mid afternoon in aug. If I can drive the car in 85 degree evenings, Ill be good.

The system looks stock except for the kuel vent which is hard to notice. Im not a concours kinda guy but I can't image the parker stampings on the hoses matter much.

I am no AC expert but I have a vac pump and a gauge set and I can diagnose basic AC problems and recharge cars fine.

I am thinking of getting a large cylinder of r134 though. Between routine AC issues with 4 cars and occassionally helping out friends with AC work, I end up buying several of the 12 oz cans per year.