'87 911 Air Conditioning questions - Yes, another A/C thread!

[iwhelan]

Sorry folks, but I did search around and couldn't find specific info about this. I see lots of people doing major upgrades with aftermarket components to their A/C systems, but that's not what I'm asking about.

My '87 911 has functioning A/C when charged with R134a, but it needs to be recharged each year, so obviously it has a leak. I don't think it was ever 'officially' changed over to R134a other than a mechanic putting a port adapter on it and charging it. It works well enough to cool the car on a hot day to keep comfortable, but usually the thermostat is kept at the coldest setting. The car is black BTW.

There does seem to be oil very slowly leaking from the clutch area of the compressor because I see oil below it, on the engine mount area, and there was some on the engine lid indicating that it was spun off. I'm assuming if oil is escaping there, that's where the refrigerant is escaping.

Is there anything wrong with me continuing to charge it yearly with R134a like I did last year? I have just been using straight R134a, nothing with a sealant included. I'd like to do a more permanent fix, but it's hard to justify the cost (right now) for the amount of times I'll need it. It would be nice to upgrade the barrier hoses, compressor, etc. some day.

Is it a waste of time to just replace the compressor without replacing other components in the system?

Thanks!

[Irhmsd]

Compressors can be had for around $400 plus the expense to evacuate and charge. Not sure if that is out of range for you but in the 911 world, that is a gift, lol. At the same time, shoot some dye in the system and go back in a couple of weeks with a black light and see where it is leaking from. You may not need new hoses, etc - that is expensive. You could have a simple leak at an O ring......yah never know.

[iwhelan]

$400 isn't bad. I just wasn't sure if this project is one of those things where spending only $400 for the compressor is waste of time if i'm not updating a lot of the other components as well, and then that's where we're into a $1000 project for something that I don't use all that often. I do want functioning A/C for longer road trips, but it doesn't have to freeze me out on a 100 degree day.

As I understand it, the original barrier hoses will leak even with R12 in the system so they'll likely leak even faster with R134a, even if the o-rings and compressor are fine.

Basically I guess I'm wondering if I should just keep recharging it each year and save my money for a proper Griffith's system, or just go for the new compressor sooner and leave the rest.

I'm assuming without changing all of the o-rings over to the R134a style, they will leak as well.

[Pazuzu]

If you can make sure that you never lose pressure fully, then you can keep charging with R134 whenever you want. It'll slowly get worse and worse, but it's the cheapest quickest option to keep a system like that limping along.

If you ever lose pressure fully, then air (and moisture) will seep in, and you won't ever get it working well again without a proper overhaul. The reason you need pressure is even 20 or 30 psi of Freon in the system will prevent any air and/or moisture from getting IN, since there will be a positive pressure pushing OUT at any leak.

Now, this is all an order of magnitude solution. You will slowly get moisture working on, and the system will slowly get worse, and you will eventually not keep up enough and the pressure will drop too far. Get one of those top off cans of R134 with the gauge on it, and use it twice a season, you'll be cheaper than an overhaul for several years.

[darrin]

r134 and r12 use different/non-compatible lubricants and (I believe) require different receiver/driers. Especially if you're considering replacing your compressor, you should probably completely evacuate the system, install r134-compatible lubricant and take whatever steps are reasonably necessary to locate and eliminate leaks.

[iwhelan]

Ok, thank you. I had feeling that it would eventually get worse and worse, but if I can put it off a bit, that may be worthwhile.

Also, someone PMed me and suggested that the black 'oil' that seemed to be coming from the clutch area might just be rubber worn from the belt. It does have that kind of quality to it, so perhaps that's it?

I do want to do a proper upgrade and not worry about the system anymore, but I'm not sure that this year is the year to spend that money on something that's not vital.

Changing over the components on my own is a possibility, but just out of curiosity, does anyone know if there is a good shop in the NJ area that knows these cars well that you would trust to do a proper system conversion/refresh?

[blucille]

Ian,

the best resource you can find is fairly local to us....suggest you reach out and see what they can do for you.

https://griffiths.com/contact/

[dentist90]

Overhauling a worn out compressor nose seal isn't very hard nor expensive to do. Some good videos on YouTube as well to guide you through. I did mine last fall and all is good now. I had the same symptoms you describe... slow leak requiring recharge every season and oily streak on the engine lid (it is not just rubber from the belt, I assure you). My seal gave out completely last fall and I lost all refrigerant. I was lucky to have a friend who is a retired AC tech and he temporarily charged the system with 134a just to do a leak check with a sniffer and around the compressor pulley was the only location that 'beeped'. That was the way I confirmed the nose seal was the problem.

Maybe you could take it to an AC shop and just have them run over your system with an electronic sniffer (better than dye as many miles of our AC tubing is kinda hidden). If the only place that seems to be leaking is your compressor just go ahead and buy a seal kit for it and DIY. You can easily replace the Drier as well and then take it to a shop for recharge. It will save you $$ for sure.

To early to tell if my slow leak problem is permanently resolved but it did hold vacuum overnight before I recharged it, which it wouldn't for even 15 minutes last fall. Good luck to you regardless.

[iwhelan]

Hey Lewis,

Certainly, and I have their site bookmarked. I think I would like to go down that road at some point, but I was just wondering if I can put off the big expense a little and keep charging it without any ill effects. I actually brought the car to our friend to do the the R134a conversion a couple of years ago. He couldn't find the leak, which seems to be pretty slow. I've been recharging it since.

Next year might be better for the full Griffiths upgrade I think. I'd rather do the whole thing properly and not worry about it, so probably just replacing the compressor isn't worth it now.

Originally Posted by sonett43

Ian,

the best resource you can find is fairly local to us....suggest you reach out and see what they can do for you.

https://griffiths.com/contact/

[iwhelan]

Originally Posted by dentist90

Overhauling a worn out compressor nose seal isn't very hard nor expensive to do.

Hmm, interesting. When I had the system initially switched to R134a, the mechanic could not find the leak, but it seems to me that it's likely coming from that seal on the compressor. Maybe just doing that seal would be a good first step before jumping into a whole new system from Griffiths. I'll charge the system and hopefully find a place that can sniff it.

[iwhelan]

On second thought, Lewis, perhaps I should contact Griffiths to see what solutions they can offer that are not a full-blown conversion to their system. I was just thinking in terms of the whole thing.

[kuehl]

You can put a new complete seal kit in a compressor provided the compressor is worthy of it. You would not waste your time if the compressor is on its last mile or past it. The only way to determine it is disassemble the compressor and inspect it.

Here is just one thread of the procedure of learning:
AC Redo – Some Questions

The issue of running with a low refrigerant level often (I believe someone thinks a positive pressure of 30 psi or something like that is an okay idea; its not) is it reduces the amount of oil the compressor see's. The compressor relies on a full charge of refrigerant to carry the oil through the system, low system pressures reduce the volume of oil and that leads to compressor wear.

[Pazuzu]

Originally Posted by kuehl

The issue of running with a low refrigerant level often (I believe someone thinks a positive pressure of 30 psi or something like that is an okay idea; its not) is it reduces the amount of oil the compressor see's. The compressor relies on a full charge of refrigerant to carry the oil through the system, low system pressures reduce the volume of oil and that leads to compressor wear.

To keep a weak system limping along, then having any pressure to keep moisture out is good enough when the compressor isn't running. Thousands of cars are driving around getting topped off one or twice a year, and getting by.

When the time comes to drop some time and money into it, THEN you make sure that you don't leak down to levels like that.

It's a safe assumption that when he goes to change out to a full boat R134 conversion with all new hardware, than he will not be keeping a suspect compressor around, so it doesn't really matter if it slowly self destructs now from poor oiling.

[kuehl]

Originally Posted by Pazuzu

To keep a weak system limping along, then having any pressure to keep moisture out is good enough when the compressor isn't running.

That sounds like you are saying two things:
A) its okay to run a system (limping along) with low pressure, and
B) (pressure) to keep moisture out is good enough when the compressor isn't running.

The issue is 911/930 owners do not know when the system is low or empty
until they start researching why the AC vent is not cold. So that means they could be running with less than a full charge. How much less they don't know.

Sorry, its "wrong" to limp along with low system pressures because you won't have sufficient refrigerant/oil flow through the compressor. The pistons still move in and out when that clutch engages and the wobble plate, bearings and piston bores will wear prematurely without a sufficient charge of refrigerant.

The refrigerant moves the oil through the system.

In terms of pressure in system, the stock system does not have pressure gauge or pressure switch to tell you when its low. And, by then, it could be too late.
Unless you don't mind spending 10-12 hours, plus the bucks, to flush out the system and replace parts.

[Pazuzu]

I'm talking about charging the system maybe twice a season, using the cans at the FLAPS with the silly gauge on them, going into a system that gets used rarely under not horrible conditions, just to keep it going for a while until one gets enough set aside to do a $1500+ systemwide overhaul. for that, which is what the OP specifically asked about, I think that my statements have been perfectly fine. It's so easy here to simply say "no ,you really need to drop some coin before you turn your a/c on again, because we all have to pay the Porsche tax" but sometimes, we just need something non-critical like this to just kinda hang in there for a while.

I'm not talking about running at 30psi and crossing ones fingers. I used that to explain why a system that has SOME freon it in will prevent moisture from getting in, which is why you can get away with the cans from the FLAPS. Once you have no pressure (cut line, etc) then moisture can easily move in, and you are finished. As long as there is SOME pressure before you give the charge a kick, then you can safely ASSUME that there is little to no moisture in there, and you can get a few more months of somewhat cool air.

Remember, then question posed was "Is there anything wrong with me continuing to charge it yearly with R134a like I did last year?" The answer is "Unless you lose all system pressure, then yes, you can continue to do that". He knows it's not the optimal solution, but he didn't ASK for the optimal solution.

[kuehl]

Originally Posted by Pazuzu

"Is there anything wrong with me continuing to charge it yearly with R134a like I did last year?" The answer is "Unless you lose all system pressure, then yes, you can continue to do that". He knows it's not the optimal solution, but he didn't ASK for the optimal solution.

And I'm not selling anything thing here. I'm simply giving words based on experience.

Most 911/930 owners don't have ac gauges. That's why they are here asking questions.

I gave my opinion and I suggest yours is incorrect. Why? Based on experience.

NO, it is not smart to continue to run a system with low pressures because it can damage your compressor and it will cost you a lot of money. Just like running an engine with low oil pressure. Not wise, rather costly.

Why is that my opinion? Because we have seen a lot of compressors that were run with low refrigerant levels. And, we have repaired the damages it causes
on plenty of cars.

Just because a handful have run their systems yearly by topping them off does not mean its "optimal". It means they are lucky.

[llangston1]

I don't want to hijack this thread but I have a similar issue with my '87 AC. It was working fine before Christmas. But in Jan when I went to run the AC it would not engage the clutch and secondary condenser fan. When I opened the deck lid there was a massive oil streak of death on the underside of the lid. I have not been driving the car much with all the rain and flooding in our area and I have not put any gauges on it yet but I assume it has lost all the freon (134a) and my hi/low pressure switch is keeping the system from engaging. I have checked all the fuses and they are fine. My compressor is a 2-3 years old new reman Nippondenso bought at a local FLAPS. Do these compressors lose their seals often? If the hi pressure switch was working correctly what would cause the nose seal to blow. What would you look for when inspecting it to see if it is worth a nose seal kit or just toss it and get another reman unit? is a total system flush warranted?

[kuehl]

Good post, no hijacking, same topic (leaks).
Unless you know the compressor rebuilder you have to be curious as to what they do.
And, in terms of your pressure switch (if you have one) you need to know the high side cut-off.

However, you are being wise to stop and wonder whats up.

If the compressor is out of warranty then simply disassemble it and inspect its residual refrigerant oil for debris with a 5x magnifier, the cylinder bores, pistons, wobble plate, pistons half bearings, reed plates, and shaft seal contact area on the shaft. Determine if its worth the effort and costs to toss in a complete seal kit, if not, buy a Denso brand (in a Denso box) compressor.

Then check to insure;
A) The front condenser fan motor works,
B) When you charge the system it is not overcharged,
C) Inspect all hose connections,
D) Common hose failures at the lift points at the rear of the car (crushed hoses), and all that you can see.
E) 86-89 year factory evaporators are prone to leaks where the aluminum tubes are bonded to the manifold,
dye tracer can't find this type of leak.

You noted the compressor and the "secondary fan condenser" were not both running.
In a stock system the front condenser fan runs when the clutch is engaged.
If you had a pressure switch added to the system typically its not wired to affect the front condenser fan.
If you have pressure switch added and another fan in its circuit it might.
In a stock system if the compressor clutch and front condenser fan do not work it might
be either the fan speed switch, the thermostat, primary relay in the smugglers box or the primary fuse on the front fuse panel.

[wwest]

Just because a handful...."

It might be worth keeping in mind that these cars (by the THOUSANDS) were all shipped with NO pressure switch and a KNOWN, factory acknowledged, R-12 leak rate that required topping off fairly often. Did owners top off on a regular basis or did they wait until the system failed to cool..?

So how many topping offs were done, AGGREGATELY, prior to need for conversion to R-134a and thereby the recommendation (requirement..??) for a pressure switch if one wasn't present.

And how many R-134a conversions were done "on the cheap" with no pressure switch installed..?? Me, GUILTY!

My conclusion: The factory compressor must be one hell of a robust unit or the issue of compressor failure due to low refrigerant not circulating oil is a wild herring.

[DaveMcKenz]

Originally Posted by wwest

Just because a handful...."

It might be worth keeping in mind that these cars (by the THOUSANDS) were all shipped with NO pressure switch and a KNOWN, factory acknowledged, R-12 leak rate that required topping off fairly often. Did owners top off on a regular basis or did they wait until the system failed to cool..?

So how many topping offs were done, AGGREGATELY, prior to need for conversion to R-134a and thereby the recommendation (requirement..??) for a pressure switch if one wasn't present.

And how many R-134a conversions were done "on the cheap" with no pressure switch installed..?? Me, GUILTY!

My conclusion: The factory compressor must be one hell of a robust unit or the issue of compressor failure due to low refrigerant not circulating oil is a wild herring.

Nice to see you back Mr. West.
Take care,
Dave