A/C help needed

Here you go!

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Thanks!

I feel pretty silly asking such a basic question, but where do you get the kind of hose support/bracket that you see on the AC line at the bottom of this picture (I can't seem to find them online anywhere. Maybe I'm not using the correct name.):

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Insulated clamps, local parts store harbor freight summit racing pep boys etc.

87-944S wrote:Insulated clamps, local parts store harbor freight summit racing pep boys etc.

Ah, insulated clamps is what they're called, now I'm finding them all over the place...

Thanks!

So I've got the new V7 compressor in and all the lines are ready to be crimped to their fittings, but I'm stuck on the wiring at the compressor.

I believe these compressors have a diode, if so that means they need to wired correctly otherwise the coil will fry.

How do you know which pin in the compressor's electrical connector is pos and which is neg?



edit: Well, I used my ohmeter, putting the leads both ways on the pins, and it seems like there is essentially no resistance in either direction, so it would seem this new compressor does not have a diode?

If it's a factory gm style compressor, the gm plug will have two wires, one green and one black, it will only plug in one direction. The black needs to go to ground and the green can be hooked directly to the black with red stripe on the drivers frame rail

Thanks Admin, I fried the coil in my last compressor so I'm being very careful this time.

Admin wrote:If it's a factory gm style compressor, the gm plug will have two wires, one green and one black, it will only plug in one direction. The black needs to go to ground and the green can be hooked directly to the black with red stripe on the drivers frame rail

Well, something's wrong, I wired it up and turned on the AC an the AC fuse blew immediately.

You're right, there is only one way the plug can go in.

On my 87 turbo the Porsche compressor spade connector on the drivers frame rail had two wires going to it - one black and one red with a green stripe.

I cut that connector off a few months ago, but iirc I think those two wires were wired together into the single spade connector for the P compressor.

So I cut off the P spade connector, crimped the black and the red w/green Porsche wires together onto a single wire, then ran that single wire over to the green wire from the GM compressor. Then I grounded the black wire from the GM compressor to the frame.

Then I turned the AC on and it's 7.5A fuse blew immediately and the GM compressor clutch didn't budge.

What am I doing wrong?

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(Click on the images to make them bigger. Sorry, first time posting pics. Not sure what the prob is.) EDIT: I fixed it for ya - 944-LT1

So it looks like there's a short in the RH supplied harness.

I just now unplugged the GM connector from the compressor, wired that green GM wire to my P request wire, grounded the GM black wire, and when I turned the AC on it fried my AC fuse so there must be a short in that 1' of harness.

Above are pics of that piece of the RH harness, what the heck does that big thick wire-looking thing that's spliced in do? Maybe it's a shrink wrap around some splices?

Do I need it? I'm guessing that's where the short is...





...and there does not appear to be a diode on my compressor. Googling around I found that if there is a diode, it's in the harness somewhere, usually near the compressor.

Do you have a volt meter? Switch it to ohms and check green to black.

It shows zero resistance grn to blk & blk to grn.

I cut the shrink wrap open, inside it the grn & blk wires from the GM connector were spliced onto the RH harness grn and blk wires. The friggin splices were touching each other causing the short. And the old compressor (that I bought a new one to replace) that I thought I had fried the coil on works just fine. Ah well, lesson learned.

Man, that is really sloppy, I'd give them heck about it!

The continuing odyssey of what at one time seemed so simple...

I've been super busy lately and haven't had much time to work on the AC, but this week I installed the new compressor, fabbed up all the new lines, flushed everything, installed new 0-rings, buttoned everything up and brought it to my AC guy.

I was using the OEM hard lines which terminate on the driver's side of the engine bay, and routed their hoses down by the bottom of the radiator and then over to the compressor on the passenger side of the engine.

Anyway, my AC guy pulled a vacuum and it held great. So he started putting refrigerant in it and a friggin' geyser erupted by the fire wall. Apparently the braided clutch line was laying on top of the low-pressure hard line and cut into it, so when pressure was applied to it it blew out.

Anyway, I don't see any reasonable way to get that hard line out so that it can be repaired - there are just too many angles in the line to pull it out and too many hoses, wires, etc., on top of it and around it.

So I think what I'll do, as I think some others have done, is cut the low-pressure hard line line somewhere near the firewall bulkhead, braze a fitting on, and simply route that hose on the passenger side of the engine bay to the compressor. I can probably re-use the hose I already have.

Anyone have any other/better ideas?

I used the existing hard line to the dryer but made up a new flex line from the firewall to the compressor on the passenger side. My hose runs thru the hole in the fender, inside the fender liner and under the frame rail to the compressor manifold.



Note: The Porsche hard lines are anodized aluminium so you must aluminium weld to aluminium fittings. The lines must have the anodizing removed where you plan to weld.

Thanks Mike, did you go through the wheel well in order to keep the lines away from the exhaust manifolds?

Yes....I routed the line that way to avoid the header.

The other line runs from the driver's side across the bottom of the radiator and under the frame rail to meet the other line at the manifold.



Top picture is the bulkhead fitting (aluminium) and the bottom is the U bend (steel) to reverse the second line over to the passenger side.



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You can also get a compression splice for your existing hardline.

Here's a filter that would work well as a splice, I have one of these in my system.

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I will admit I have NOT read all 8 pages of this thread so if its posted somewhere else within this thread I apologize, im just trying to help...
The reason im posting:
When using a expansion valve or "H-Block" as there sometimes called manufacturers also use Reciever Dryers. Which as we all know is what Porsche uses. Well these dryers have dessicant crystals in them which absorb moisture in the AC system. My point is once the lines in your AC system has been opened for a relatively short period of time (like a few hours) then your drywer NEEDS to be replaced. I dont care how long you put the system into a Vacum it will never remove all the moisture. Moisture BTW is the leading killer and of AC component failure. It will tear up the compressor and cause rust/corrosion through out.

So replace those dryers fellas!

thanks for all the AC modding info
Bryan

Flier Mike, thanks for the pics!

87-944S, the cut in the line is right on a bend. I have one of those same in-line filters you linked to on my liquid line in the straight section near the high pressure service port, I'm not sure it would work where the cut is on the bend.

Can you link me to a compression splice for the low-pressure hard line?

I've been googling around but have not been able to found one.

Bryan, you addressed exactly what I was worried about. I did put in a brand-new drier just before I drove over to my AC guy, but the system has been open now for a few days.

Here's a compression fitting that should work;

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For the drier, any universal dryer will work, you should be able to pick one up for 30 bucks or less.