vilhelm

Recently my air conditioner stopped cooling. I took the car into an air conditioning shop for diagnostics and found there was no freon at all in the system. I had the system charged and dyed. Immediately found a leak in the service valves and replaced those.
Everything has been fine for the last two weeks until today when I have no cooling again.
I suspect I have a slow leak somewhere.
I'm in need of trouble shooting hints to help minimize the steps. The system takes a little over 2 lbs of freon so each time I charge it is about $130.00 just for the freon so I would like to minimize these cycles.
Or is that a waste of time and money would I be better off just replacing the system and get it over with? If that is the route are there any recommendations on any better systems to go with? I currently have a nipondanso..(spelling? ) compressor.

thanks

Drew_K

Bruce,

This doesn't exactly answer your question, but I had the A/C in my 92 C2 converted from R12 (which is what you have) to R134 over at Koby's. Cost around $300 AND the best part is that R134 is about $16 per pound instead of $65.

Are you sure the freon is gone? It could be the compressor, evaporator, etc. Either way, no A/C in Houston sucks, especially now.

Randall G.

Hey Drew,

How's that R-134a working for you? If it works for you in Houston, it will certainly work for me here on the coast . Did you get a new receiver/dryer for the $300?

My A/C still blows cold air, but not as cold as it can. I'm in research mode, comparing:

1) Recharge with R-12. About $200. Probably will need repeating every few years.

2) Drop-ins. I tried to contact the Freeze-12 people (Jay W. had good luck with them), but my calls and e-mails have gone unanswered.

One big problem I can see with drop-ins. Will the particular vendor you've chosen still be around in two years when you need a fill? Will anyone else be willing to evacuate your (potentially) obscure drop-in?

3) Convert to R-134a:

-Advantages = common & cheap. You can even do your own fills. You can't buy R-12 or most (all?) drop-ins without being certified.

-Disadvantages = higher operating pressure (leaks) and some loss of cooling capacity.

In order to remain reasonably brief, I've not tried to create an all inclusive listing of pros/cons with my above list.

Oh, and to address Bruce's situation .... might be a good time to move away from R-12. I would hate to be chasing (significant) leaks at $65/pound.

Adrian

Dear Bruce,
Sadly I think you have leaks in your evaporator hoses or the expansion valve. The only way to detect these leaks is with pressure in the system (Not freon of course) and then go painfully step by step to each component including the condenser (which can be damaged, a recent report was of a condenser holed by a stone) and check for physical leaks. There is no other way to do this,
Ciao,
Adrian
911C4

PS: You might be lucky and hear the leak but murphys law says you won´t. You will need to check the high and low pressure circuits. Anything can leak in this system.

GaryN

Hi Bruce,
As Adrian mentioned I had a stone through my condensor unit and also went through the costly route of getting 2 fills (1 to find the leak and the other to fill the system after the leak).
A very quick check to see if you have pressure in your system is to un-screw the cap on the compressor value (this is where they fill your system) and give the value a very quick press, you'll immediately see if there is pressure in the system.
Remember the clutch on the compressor will NOT kick in if there is no pressure in the system, this is also a tell, tell sign of no gas.

If there is no gas in the system, (you said about 2 weeks usage and then failure) the leak is SMALL i.e. not visible. You said they put in dye? You will need to take a UV light and look for the glow (leakage).
The first place I would look is at the condensor and the 2 seal's at the top of the condensor, then the dryer, then the two pipes in the luggage compartment (near the fuse box), then lastly around the compressor.
The condensor is highly subseptable to stone's, after replacing my condensor I put a small "mod" in place to avoid this in the form of a fine aluminium grid and cable-tied it behind the existing grid.

DON'T use R12 for "finding" leaks it too expensive.. let them pressure test with dye (as you've done)

Hope you find the leak soon.
Gary '91 C2

PS. My money's on
1.there's a small hole in the condensor
2.the 2 seal's on the condensor are gone

Adrian

Dear Gary,
I am afraid I have to strongly disagree with your advice. It is highly dangerous to personal health to eject any material under high pressure anywhere near your person. Materials such a freon can and have entered the human body through the skin of a person under high pressure, leading to a fairly rapid exit from this world. Creates bubbles in your blood stream and when they reaches your brain, goodnight charlie.
This is a terribly unsafe procedure. I do not recommend deliberately letting freon into the atmosphere either. However if such a test is wished then use a tyre gauge or similar item and keep fingers well away from high pressure valves. Personally I recommend the use of a proper pressure gauge for airconditioning systems which can be purchased or borrowed from your friendly local airconditioning guy.
Ciao,
Adrian
911C4

PS: Gloves do not help either. If you wish to research this potential danger further just log onto a military safety related site. The USN for America. They have quite a lot of data on this and other hazards which may not immediately leap out to the average person as a hazard.

Jeff Curtis

The local P-Car authority (shop) here in VB is on their third 964 with a leak in the evaporator coils. Seems there's a lot of moisture that gathers down there, the insulation between the coils and the body of the car tends to wick it up and hold it...also the possibility of chaffing seems to occur at the first bend in the evaporator coils.

This is a VERY involved procedure to change them out...involves the removal of the fuel tank, fuse box and parts of the underdash.

Your mechanics should charge your system just enough to get the compressor to cycle, and of course, include a dye pack. They can then use a hydrocarbon "sniffer" if they can't see the leak with the dye.

Sticking the "sniffer" up through the drain holes in the body of the vehicle will indicate if there is a leak in your evaporator coils - of course, this will have to be done on a lift.

As for Adriane's concern, well, let me address that. The inlet valves, basically high pressure valve stem type valves would allow for someone to "blip" them for a moment to check for pressure, while potentially unsafe.

The proper way to check for pressure is the use of a device that looks like a tire pressure checker except that it measures MUCH higher pressures. If you use one of these babies, and it doesn't register...I guess the next step a lot of people would take is to work the valve manually to see if they hear anything come out...which they would if there's any pressure in there at all.

Let's face it, finding a damned AC leak is no fun at all...I just took my stuff off and said "F" it! - as my evaporator coils have apparently sprung a leak. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

vilhelm

Thanks all..I guess there is no magic solution.

It seems that even if I convert to R134 I still must isolate my leak and the procedure will be costly and time consuming.
On the subject of the R134 convervsion..what all is involved in this? new compressor for the higher pressures? etc.

Drew..how is it holding up in Houston..last week at 95 degf should have been a good test.

Adrian

Dear Bruce,
If there were magic solutions please send some my way. A little bit of magic could wonders for me ands my family right now.
Getting back to serious issues at hand. Aircon problems need either a DIY person with system experience and the correct test equipment or an aircon shop. There are no cheap and easy solutions when trying to find a leak in a sealed system where you cannot see the stuff that leaking. Plus it is all mounted in places in an auto which is just plain hard to get at.
Ciao,
Adrian
911C4

vilhelm

Adrian:
I sincerely hope that you and your's are finding direction and peace after your recent tragedy. I think I need a personal redefinition of magic. It must be there somewhere, I need another look.

I'm getting ready to fly to the west coast and pick up my wife and the 964 and drive back to Houston. My thoughts are to recharge the aircon out there; hopefully I can get back to Houston via Denver on the charge. In Houston I can have a bit more control over the diagnosis and repair.

Then I can go after this brake squeel problem.

Randall G.

If it's any consolation, the wonderful Grusse says that the 964's AC system was designed with R-134a in mind (for example, use of barrier hoses, compressor will run R-134a). But, when the 964 was introduced, R-134a was not available yet. So Porsche kept filling with R-12.

That said, if you look through PET (and Grusse will tell you this, too), several A/C components were revised in '93 when R-134a was introduced. For example, the receiver/dryer, expansion valve & compressor.

There are several recent threads on what it takes to convert from R-12 to R-134a. The only fairly expensive component that needs to be replaced (assuming your current system is in good working order) is the receiver/dryer. Here's one of the recent threads:

<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=4&t=001879" target="_blank">Convert to R-134a</a>

DaveS

My compressor is leaking from the seals I believe. Any ideas on the cost to fix this? Funny thing is that the compressor was replaced by the Previous Owner 18 months ago!!!

It is no longer under warranty

Randall G.

Hi Dave,

Rennlist sponsor <a href="http://www.pelicanparts.com/catalog/shopcart/911L/por_911L_exhaus_main.htm" target="_blank">Pelican Parts</a> has rebuilt compressors to fit N/A 964s for "only" $240. Sorry to hear that the fresh rebuild is already leaking, but as far as I know, another rebuilt unit is your best option. I can only presume that whoever rebuilt your existing unit (it wasn't new, was it?) did a lousy job.

Drew_K

The conversion to R134 seems to work pretty well even in the Houston heat. As long as the car is parked in the shade, it blows pretty cool air even in stop and go traffic. If it's been sitting in the sun, it takes at least 5 minutes to cool down if the car is moving, longer if stuck in traffic, but that's not too different that any other car. Our Camry with R134 definitely cools better, although it's a white car with DARK tinted windows. We also have an old Integra with R12, and A/C is an absolute icebox.

I can't make a good comparison to R12 because I was low on freon when I made the switch. Bottom line though is it works fine as long as the car doesn't sit under the sun all day.

Drew
92 C2

christian

It/s really not good for the environment doing all that diy testing with R12. Can't understand the US government, why they still allow it. It is forbidden in most other parts of the world. Let the conversion to R134a do by an expert. If you suspect a leak, no problem, he will put in some dye and the source of the leak can easily be found. I did the conversion to R134a on my Ferrari and it blows cold, ice cold! Cost was 375 Canadian dollars inc. tax.