HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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A/C help needed

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Re: A/C help needed

Post  Porch on Mon Jun 20, 2011 3:03 pm

No, the condenser style changed between R12 and R134. The R134 units are "parallel flow" while the R12 units are "serpentine".

I'm far from an expert on A/C, but my understanding is that this is done because R134 is much less efficient as a refrigerant. I found a site with some good info: [You must be registered and logged in to see this link.]
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Re: A/C help needed

Post  Porch on Mon Jun 20, 2011 3:05 pm

Looks like that site has some good universal condensers: [You must be registered and logged in to see this link.]
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Re: A/C help needed

Post  acorad on Mon Jun 20, 2011 4:02 pm

Thanks Porch, looks like the dryer needs to be replaced too if your system has been open for a while or if you are changing refrigerants.

r12 is still available, and really isn't all that expensive. I'm now thinking of using r12 and downsizing to a smaller parallel flow condenser because I just discovered that the reason my radiator keeps leaking is because it scrapes on the ground occasionally coming out of driveways and such (I thought/hoped it was the bottom of the front bumper cover that was scraping) so I'll need a smaller rad as well...


Last edited by acorad on Mon Jun 20, 2011 4:54 pm; edited 1 time in total
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Re: A/C help needed

Post  v8carreragts on Mon Jun 20, 2011 4:53 pm

Your stock condenser is large enough for R134a. The reason they changed the condensers is because most cars had marginal condensers to begin with. R134a is a little less efficient than R12 so parallel flow condensers were developed.

The stock 944 condenser is already large for the size of the system so it will not be a problem. However, if you think it may be too corroded or fatigued now is the time to replace it.

I have bought parallel flow condensers from ackits.com before. The quality is good and delivery was quick.
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Re: A/C help needed

Post  Porch on Mon Jun 20, 2011 5:51 pm

Okay, that's good to know...thanks v8carreragts!
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Re: A/C help needed

Post  acorad on Tue Jun 21, 2011 6:38 pm

Thanks V8, and you're right the condenser in my car is almost as big as the (Ron Davis) radiator itself.

I've been looking at the [You must be registered and logged in to see this link.] from Vintage Air.

My thought is that these lines can be bent such that they hug the compressor closely, compared to buying ready-made angled fittings and connecting several of then together. The ready-mades would end up hanging several inches below the compressor while the U-Bend-Em's could hug the compressor shape closely.

Vintage says to use a "proper tubing bender" to bend the the U-Bend-Ems. I assume I'll need #8 and #10 lines. The #10 lines are approx 5/8" OD.

Does anyone have any experience bending tubes like these? Can I do it muself, or do I have to find a shop to do it? What kind of shop does this kind of work?


Last edited by acorad on Wed Jun 22, 2011 1:27 pm; edited 2 times in total
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Re: A/C help needed

Post  87-944S on Tue Jun 21, 2011 6:46 pm

Yep, I have used them, just get a tubing bender from any auto parts store, they bend super easy. Bending by hand if you need a tight bend will crimp them.
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Re: A/C help needed

Post  Porch on Wed Jun 22, 2011 11:19 am

Most tubing benders are made for 1/4-3/8" lines, though. I would check eastwood for a tubing bender made for stuff that size.

I'm actually curious to see how it comes out. It definitely seems like you could end up with a cleaner product by doing it yourself!
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Re: A/C help needed

Post  v8carreragts on Wed Jun 22, 2011 9:42 pm

McMaster Carr and Grainger has them....a little pricey though.
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Re: A/C help needed

Post  Porch on Wed Jun 22, 2011 10:33 pm

I don't recall what size the conduit benders usually are (and they're not made for tight turns) but that may be a low-buck solution.
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Re: A/C help needed

Post  Marky522 on Wed Jun 22, 2011 11:28 pm

I have the bender you need, I bought it since i ran all hard tubing on my car for fuel, oil and coolant. I bought the -10(5/Cool bender, and used it for the -10, and -8 line by taking a piece of the -10 line and laying it in the bender then it would bend the -8 just fine. The comment about them being pricy is true this is the style I bought. Shoot me a PM if you need it, I am sure we can work something out so you can use it.

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Re: A/C help needed

Post  acorad on Fri Jun 24, 2011 11:32 am

Mark, PM sent!
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Re: A/C help needed

Post  acorad on Mon Jun 27, 2011 4:26 pm

Well, it looks like the u-bend-it tubing idea isn't going to work out as the tightest bend you can put in the 5/8 suction tube is about 2" which really isn't tight enough. I suppose I could have had the tubing cut and welded into 90 angles, but I decided to go with pretty much the same setup that 87-944S has on page 3 of this thread.

One of the things I like about his setup is that the short ~ 1" piece of hose between the two angled fittings near the AC manifold are able to "give" a little which is probably a good thing to relieve stress as the hoses are mounted on one end to the engine (compressor) and on the other to the radiator mount, and those two mounting points probably bounce around somewhat independently.

I'm also splicing in a low-side port in the suction line near the OEM high-side port near driver's side strut tower, and I ordered a new dryer and a new expansion valve as well as new O-rings.

And I got one of those radiator fin comb things and I'll try to freshen up the condenser fins and blow out the dead bugs, etc.

Since r12 is still relatively cheap, and the "boss" demands ice-cold AC, I'm staying with r12. I got certified so I can legally buy r12.

Is there anything I'm forgetting?
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Re: A/C help needed

Post  acorad on Tue Jun 28, 2011 8:16 pm

Hi all, so now I'm wiring the A/C compressor in, and, being a newbie at wiring, I am finding some challenges!

I jumped the low pressure switch since my AC system is open and therefor there is no pressure, turned the ignition on, pushed the snowflake AC button in, and I have almost 13 volts at the black P compressor wire, so things are looking good.

I then pigtailed the two P wires over to the two GM wires coming from the compressor, but the compressor clutch won't engage.

I tried wiring it black P wire to black GM wire/colored P to colored GM, as well as black P to colored GM/black GM to colored P, but it didn't seem to make any difference, the clutch did not engage either way.

To confirm that the clutch does work I then pigtailed from the compressor straight to the battery and the compressor clutch does engage (black GM wire to negative battery terminal, colored GM wire to pos).

Should I perhaps be doing something differently to ground the system? Should the ground wire from the compressor go to a ground on the car body, or something? If so, what do I do with the P ground wire?

Any thoughts?


Last edited by acorad on Tue Jun 28, 2011 9:04 pm; edited 1 time in total
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Re: A/C help needed

Post  acorad on Tue Jun 28, 2011 9:03 pm

Ah jeez. I think I just now fried my ac clutch coil by jumpering it to the battery the wrong way (with the pigtails switched).

I tested it my multimeter by connecting one probe to each of the two wires from the compressor and got 0.00 ohms, that means the coil is fried, right? Zero impedance?
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Re: A/C help needed

Post  v8carreragts on Tue Jun 28, 2011 9:50 pm

Why would it make a difference? It's just a coil. I would be like connecting a bulb backwards.

But you should be able to get a resistance reading or the coil is open.
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Re: A/C help needed

Post  acorad on Tue Jun 28, 2011 9:54 pm

Thanks V8. But I still can't figure out why previously the clutch would engage when pigtailed of the battery, but not when it was pigtailed off the P harness when the P harness had almost 13 volts.


Last edited by acorad on Tue Jun 28, 2011 10:01 pm; edited 1 time in total
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Re: A/C help needed

Post  acorad on Tue Jun 28, 2011 10:01 pm

Oh, and also now my AC clutch doesn't work when pigtailed off the battery either...
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Re: A/C help needed

Post  Arthropraxis on Tue Jun 28, 2011 10:14 pm

My GM compressor was grounded to the block. The compressor was activated by a green clutch relay wire, yours may be a different color. The Porsche line to the Porsche compressor had the two wires connected into one spade connector that connected with one wire to the compressor's clutch. I left the GM's compressor grounded to the block and ran the green wire over to the Porsche connector on the drivers side frame rail that the original Porsche compressor connected to. I have been told it should work like this. We will see soon.
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Re: A/C help needed

Post  acorad on Tue Jun 28, 2011 10:31 pm

Thanks Anthro, I'll try it that way once I figure out the coil issue. I've been reading that some clutch coils have a diode that makes it polarity sensitive.

From this discussion: [You must be registered and logged in to see this link.]

"The coil on your replacement compressors has a built in diode-- it is polarity sensitive-- look really close at the base of connector on coil, there will be a + and a - negative sign."
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Re: A/C help needed

Post  acorad on Tue Jun 28, 2011 11:07 pm

Can someone confirm that my method of testing the ac compressor clutch coil is correct - merely use a mutimeter/ohm meter across the two wires that go from the compressor plug to the harness?

Everything I google says "test the resistance of the coil," but nothing says exactly HOW to do that.

[edit] OK, as I said, I am a newbie at wiring, so one last post before I go to bed.

I just grounded one of the wires from the GM compressor and applied power to the other GM wire via Anthro's setup (both P wires in contact with the one GM compressor wire) and I blew the ac fuse in the fuse block.

I assume that means that there is no resistance through the ac clutch coil and that coil needs to be replaced?
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Re: A/C help needed

Post  944-LT1 on Tue Jun 28, 2011 11:58 pm

If you are reading zero ohms, yes, its a dead short. Although the coil itself is not polarity sensitive, the diode may be internal so yes, the compressor is polarity sensitive.

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Re: A/C help needed

Post  acorad on Thu Jun 30, 2011 12:14 pm

Thanks all. I guess I'll be buying a new compressor. Seems like there are dozens of oem and aftermarket brands as well as remanufactured units, etc., any particular brands to avoid?
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Re: A/C help needed

Post  acorad on Thu Jun 30, 2011 12:38 pm

fwiw, according to this discussion you can merely remove the two middle o-rings of the RCV to force a variable compressor to be constant full-stroke: [You must be registered and logged in to see this link.]
fliermike45 wrote:The Valve I removed from the compressor and the location in the compressor where the valve fits.
Valve is retained by a circlip. Note that the small end of the valve has been closed with a touch of weld.
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Re: A/C help needed

Post  acorad on Tue Jul 05, 2011 3:21 pm

87-944S, where did you get/what brand of inline filter did you use?
87-944S wrote:Here's some pics, the cylinder with blue ends is an inline filter with compression fittings.
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Re: A/C help needed

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