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Old 08-21-2007, 10:44 AM   #1
D.C.
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Default My AC is broke, what would you do?

I have been struggling with what to do with my AC, and thought I would solicit your opinions.

Here is the situation. 1986 Targa Carrera. High mileage car that runs and drives great. AC is stock unit, and does not work. The known issue is the compressor clutch, which engages but slips like crazy. There was some nasty black goo that has slung out of the compressor clutch over time. So the compressor clutch is trash. Compressor turns over OK and you can feel the compression stroke. The system has pressure, so there are no big leaks, but I suspect that it needs a charge. Front condenser fan appears to be working, and the blower on the evaporator works fine.

I have several options here.

1) The cheap short term option.
Replace the compressor clutch with a used unit, if I can find one. Charge the system and see if it works. This would allow me evaluate the system, and its performance to determine if an upgrade is required. Probably get me through the summer as well.
Cost is the price of a used clutch (anybody have one?). I already have a couple old cans of R12.

2) Full blown high performance AC upgrade. I spoke to the Guy at Griffiths, and he recommended the complete makeover. New compressor, new hoses, additional fender mounted condenser with fan, new drier, new evaporator, new expansion valve, new this, new that, after a while my head started spinning and I can’t remember what else he said. But I do remember that it was some serious $$$. He said that if I did all these things that I could run my AC with the convertible top down on a 100 degree day, and I would be cool. I believed him, but at this point I am not convinced I want to spend that kind of $$$ for a high performance AC.
Cost is serious money, but probably worth it.

3) The compromise, long term solution. Replace the compressor with the RennAire Sanden 507 kit. Install new barrier hoses. Convert to R134 (of course). New drier, and expansion valve. Clean evaporator coils. This solution gives me stock factory performance which may not be suitable for someone in the deep south, but probably good enough for me.
Cost is around $700

4) The upgraded compromise, long term solution. RennAire Complete upgrade system. This kit includes everything you need to upgrade your AC. RennAire Serpentine Evaporator, expansion valve, new silicon hi-temp aircraft duct work, the RennAire Evaporator Seal kit, ProCooler kit, complete set of reduced diameter barrier hoses, RennAire/Sanden 507 compressor with adapter bracket, new V-belt, fitting sealer, nuts and bolts, evaporator insulation thermal package, clamps, 134a adapter kit, and system oil.Systems. This kit should provide a bit of a performance upgrade over the standard system.
Cost is around $1200.

Before I ask for your advise, let me tell you what I am not going to do. I am not going to remove the AC to save weight. I am not a track guy, not yet anyway. I drive this car for fun, and I drive it in the summer when it is hot outside. I currently leave it in the garage if the temp is over 90.

So what would you guys do? My inclination is to start with option 1, and if I am not satisified, move to option 3 or 4. One factor here is that options 2,3 and 4 would need to be a winter project for me, and I would like to have some AC for the remainder of the summer.
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Old 08-21-2007, 10:51 AM   #2
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GO for No.1
Cheaper.
Quicker.
Easier.
And (hopefully) cooler over summer.

Do some more research while it's going and try the other opions when you have more time (winter) and money.

That's what i would do.

Good luck
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Old 08-21-2007, 12:00 PM   #3
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i have an 87 and live in nc...90+ and thought about changing the system for big money...anyhow i charged my system and the car is much cooler...150 bucks..they put dye is the system to see if there is a leak..i would like another vent that would blow directly on me,but the car is much much cooler..i heard that after spending thousands on the new system,it was'nt that great..j
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Old 08-21-2007, 01:55 PM   #4
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You have Targa and you're concerned about the A/C working...?

I ripped the one out of my '78 targa.
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Old 08-21-2007, 02:18 PM   #5
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All, thanks for the feedback.

Frank, glad you agree with my logic, but looking at your screen name (psychoideas) makes me wonder If I should re-think this.

Joey, you are a bit further south but about the same climate as in Virginia. The dye is a good idea, I think I will try that.

wwest, I have to tell you that when its 100 degrees out, 90% humidity, and you have the top off, the sun beating down on you, and you are stuck in traffic, its hot!!!! Its really HOT!!! When its that hot, you put the top on and turn on the AC. That is of course assuming that your AC is working. I think it may be a bit cooler in Redmond in the summer than it is here in Virginia. I do like the idea of not having to mess with the AC. Its just one more thing to maintain, robs power, and adds weight. But I need to have it to enjoy the car in the summer.
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Old 08-21-2007, 02:51 PM   #6
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You do not need to spend a fortune to make the system work right.

1. The "black goo" slinging out of the compressor is likely contaminated oil seeping from a bad seal at the front of the compressor. Is the "goo" up on the deck lid, above the compressor? If so, it's almost certainly oil.

2. A rebuilt Nippondenso compressor and clutch can be had for less than $300. It's not a "magical" compressor, and most a/c compressor rebuilders have them on the shelf. Check eBay, also (I just saw one for $167, with a clutch, including shipping). Or, for about $350, you can get a Sanden 507 with adapter plate from Rennaire.

3. You can get a hose kit from Rennaire for about $350. This will replace all of your leaky non-barrier hoses with barrier hoses. Replacing the hoses is not a difficult job....just dirty and time-consuming.

4. If you're not going to do any work on the system, then convert to R134a. If you're going to replace the hoses and compressor, if I were you I'd stay with R12, especially if you're not going to do any custom work like adding condensers or a ProCooler. I have a ProCooler, btw, and highly recommend it. R12 simply cools better than R134a.

So, for $700 or less (plus the cost of evacuating and charging) you can have a functioning R12 system. You won't be able to hang meat in your car, but it will be relatively cool. I've made several modifications to mine, and I'm getting vent temps in the mid-to-high 30s. A properly maintained and charged stock system will give you mid-to-high 40s.

If it were me, I'd wait until winter and do the following:

1. Barrier hoses.
2. New (rebuilt) compressor
3. ProCooler
4. New evaporator and expansion valve
5. Add a condenser/fan assembly
6. Remove existing condensers and have them flushed and checked
7. Evacuate/vacuum for at least three hours.
8. Properly recharge (engine at ~2000 RPM, air moving over rear condenser) with R12.
9. Add Griffiths Kuehl vent (or make your own)

I hope this helps.

Scott
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Old 08-21-2007, 04:37 PM   #7
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Scott,

Thanks for the info on the black goo. It was slung all over the deck lid. I had assumed it was part of the clutch, but compressor oil makes more sense. That leaking oil probably contributed to the failure of the compressor clutch.

I was going to ask for more information about the ProCooler, but there is a good article on the RennAire site that explains how it works. It is a good read that made a believer out of me, now that I understand how it works. Here is a link to the article for those interested.

http://www.rennaire.com/MiddletonArticle.pdf
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Old 08-30-2007, 02:28 AM   #8
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pull the a/c, sweat and use the go pedal with your new found HP to make more wind in the open top.
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Old 08-30-2007, 06:00 PM   #9
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Definitely go for #1. You might not need much, you might need a ton, but start slow.

You might also do the barrier hoses if you find you are losing freon.
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Old 08-31-2007, 09:39 AM   #10
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Quote:
Originally Posted by D.C. View Post
2) Full blown high performance AC upgrade. I spoke to the Guy at Griffiths, and he recommended the complete makeover. New compressor, new hoses, additional fender mounted condenser with fan, new drier, new evaporator, new expansion valve, new this, new that, after a while my head started spinning and I can’t remember what else he said. But I do remember that it was some serious $$$. He said that if I did all these things that I could run my AC with the convertible top down on a 100 degree day, and I would be cool. I believed him, but at this point I am not convinced I want to spend that kind of $$$ for a high performance AC.
Cost is serious money, but probably worth it.
.
I did this and it was money well spent.

Steve
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Old 08-31-2007, 09:48 AM   #11
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Thanks to everyone for the advice. The only thing I have accomplished so-far is to draw some conclusions.

I decided not to go with option 1, which was to replace the clutch and charge the system. The reason for this is that Scott pointed out that the black goo was oil leaking from my compressor. There was lots of black goo in the engine compartment, so I am sure the compressor is in bad shape. I was also unable to locate a new or used clutch at a reasonable price. A new one is $200, and the cheapest one I could find used was $100 plus shipping. I was a bit surprised at the used prices, as many people remove the AC from their cars, I would have thought someone would be giving old compressors and clutches away. Apparently not.

So here is the plan. The summer heat is almost over, so this will be a fall/winter project which will include the following. New AC compressor, new barrier hoses, new expansion valve, new receiver drier (perhaps a pro cooler), clean and inspect the evaporator, convert to R134. I also found some information about sealing the air spaces around the evaporator. Apparently the old foam that was used to seal these 20 years ago turns to dust, which clogs the evaporator and allows the air flow around it instead of through it, which kind of defeats the purpose. So I will be checking and resolving this potential issue as well.

I am going to read the article on the pro-cooler again, and make a final decision on that in the coming weeks. The pro-cooler adds a couple hundred dollars to the cost vs the standard receiver drier. I think it must add a couple of additional lines to the system as well. I will have to look at where those new lines would be connected, and how they would be routed.

So there is the plan, essentially option 3 "the compromise, long term solution".
I am not looking forward to running all those lines, but it should be an interesting winter project.

Scottitude: I dont like to sweat, but I do like to use the go pedal.

Murphyslaw: I was leaning towards number 1 all along, the turning point was the leaking compressor. If I need to replace the compressor, I should probably replace all the lines, and if I am opening up the system, I will need a new receiver drier, and if I am going that far, I might as well replace the expansion valve, and have a look at the evaporator. For some reason my projects seem to expand in direct proportion to the size of my bank account.
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Old 09-01-2007, 12:32 PM   #12
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A/C is a "slippery slope." Once you get started, it's sometimes difficult to stop.

One thing I would strongly recommend is adding a condenser and fan assembly. The real problem with Porsche a/c is that there isn't enough condenser surface. Several people have made condenser/fan assemblies for their rear left fender. (Griffiths makes a top-notch kit for the rear left fender.) I put a condenser and fan in my front left fender and relocated the washer resevoir. Some people have underbelly condensers. If you're going to have the system open, you should give some serious thought to adding a condenser. Also, I'd spend the extra bucks and get a ProCooler. They work, and if you're going with R134a you're going to need all the help you can get. The ProCooler does add two extra lines, but it comes with very good instructions on how to route and install them. Also, Ron Maxwell of Rennaire is great at providing help over the phone if you need it.

Also, the "black goo" could be a sign of contamination in your system. You're already replacing the hoses, but you should also remove all of the existing condensers and have them flushed and checked for leaks. Most local auto a/c or radiator shops can do this for you.

Good luck, and keep us posted on your plans and progress.
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Old 09-01-2007, 08:57 PM   #13
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I have a '89 3.2 coupe and live in the southeast US. Last year I did the following to update the A/C:

- new Sanden compressor (stock unit was leaking)
- converted to 134a
- new Kuehl evaporator + new blower motor
- Pro-Cooler
- Kuehl center vent & variable fan controller (to better control fan noise level in the car)

The result of my upgrade is that the A/C is definitely blowing much colder. However, the system still cannot keep up with the high 90s that we have had over the last couple of months. I believe I will need to replace both stock condensers with new design sepentine models (as sold by Griffiths and others) to make further incremental improvements. I have also seen many positive comments about adding grille fans for the rear condenser and may consider that also.

Regards,
David
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Old 09-01-2007, 09:15 PM   #14
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David: The biggest problem with the 911 a/c is lack of condenser surface. If you're going to have your system open, you should consider adding a condenser/fan assembly.

Scott
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Old 09-04-2007, 12:30 PM   #15
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Scott: A slippery slope indeed !! I totally agree on removing and cleaning the condensers. I agree that additional condenser area will help. I need to look into pricing for that. I did discuss it with the guy from Griffiths, but at that point in our conversation, I had stopped counting, so I dont remember the cost. I do have some concern about installing that extra condenser next to my catalytic convertor. It is pretty hot in that area.

David W: Seems there is a strong consensus that the pro-cooler is worth the extra dollars. I am leaning toward adding this to my parts list.
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Old 09-04-2007, 12:30 PM
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