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  acorad on Tue Sep 13, 2011 2:46 pm

Thanks 87-944S, but I don't think any of those fittings will work. The low-pressure P hard-line is 16mm aluminum, and none of those fittings look to be correct for that. I also couldn't find any 16mm in-line filters or 16mm splicers/couplers/unions anywhere else.

As much as I hate having to go back to the drawing board, unless I can figure out someway to get the damaged line out, I think I'll have to do something like fliermike's setup.
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Re: A/C help needed

Post  87-944S on Tue Sep 13, 2011 3:35 pm

Well, if I read this right I would have seen you meant the low side, not high side! Sorry about that. I did the same as FlierMike, I cut the tube off, brazed a crimpable end to it and crimped a rubber A/C hose to it. Running it behind the engine and around outside of the suspension. I wrapped it in heat reflective tape just in case. Discounthydraulics is a good cheap source of the A/C fittings and hose.
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Re: A/C help needed

Post  acorad on Tue Sep 13, 2011 3:58 pm

Thanks 87-944S, I've been looking through your gallery to see if I could see the AC hose, but I can't see it. However, beautiful build!
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Drier

Post  fliermike45 on Tue Sep 13, 2011 9:49 pm

I just bought a new 944 drier/receiver from Pelican for 11 bucks.

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Re: A/C help needed

Post  acorad on Wed Sep 14, 2011 11:41 am

fliermike45 wrote:I just bought a new 944 drier/receiver from Pelican for 11 bucks.
You must have bought their last one, they're out now!

No worries, I just picked one up this AM at Napa for $20 to replace the brand-new one that I installed last week that has been open to the atmosphere.

I really like the Napa unit. It's the same size as the OEM, whereas the one I installed last week (I forget where I got it from) is about 1/2" less in diameter than OEM, and the Napa unit comes with a new low high-pressure switch and some new o-rings (and some aluminum line inserts and plastic clips that I assume I won't be needing for my 87 951.)


Last edited by acorad on Thu Sep 15, 2011 12:17 pm; edited 2 times in total
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Re: A/C help needed

Post  acorad on Wed Sep 14, 2011 5:14 pm

Hey there, I think I found a splice that might work: [You must be registered and logged in to see this link.].

The only issue I can see is that it's sized for 0.625" (5/8") but the P high-pressure lines are 16mm (0.630").

Seems to me the rubber-looking green seal sleeve doesn't care about the extra 5 thousandths, and if the brass-looking ring is too tight on the A/C line I can just use a file to open it up a little...
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Re: A/C help needed

Post  87-944S on Wed Sep 14, 2011 7:31 pm

That looks just like the inline filter I'm using, without the filter part! Mine was english fractional sizes as well. It worked great, it holds vacuum no problem, I have an A/C gauge set and vacuum pumpmto prove it! I think you will be good to go.


Last edited by 87-944S on Wed Sep 14, 2011 7:31 pm; edited 1 time in total (Reason for editing : clarification)
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Re: A/C help needed

Post  acorad on Thu Sep 15, 2011 11:11 am

Well, I just called them and it turns out they do have a 16mm splice, so we're good to go.
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high pressure switch

Post  sbwrench on Thu Sep 15, 2011 11:49 am

Not to hijack but this is the best a/c thread to date so I thought I'd ask a question. On an 88 model will the high pressure switch (stk. Porsche) send the proper signal to the PCM (95 LT1). If not can a stk. GM pressure switch of the correct year be plumbed in? Thanks.

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Re: A/C help needed

Post  acorad on Thu Sep 15, 2011 12:27 pm

No hijack at all, I'm interested in the answer too...
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AC Request

Post  fliermike45 on Thu Sep 15, 2011 12:48 pm

I have hooked Pin 13 (AC Request) on T21 (14 pin connector) to the AC Request line on the LS1 PCM......I hope this is going to work.

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Re: A/C help needed

Post  87-944S on Thu Sep 15, 2011 4:46 pm

Does that pin go to plus 12 when you turn the A/C on?
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AC request

Post  fliermike45 on Thu Sep 15, 2011 6:08 pm

Not sure, I assume that it does because my compressor is connected to the PCM so the AC request line has to wake up the PCM. Have not run the engine with AC yet, system not charged.

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Re: A/C help needed

Post  sbwrench on Fri Sep 16, 2011 8:28 am

I'm having the low pressure line replaced today and the system recharged. Right now I only have the compressor set to turn on off of the "snow flake" switch. Once I get it back I'm going to get everything to talk to the pcm; a/c reguest, high pressure switch, fans, etc. I know the LT1 is different then the LS but I'll document the wiring as I go along. It may be helpful.

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Re: A/C help needed

Post  sbwrench on Fri Sep 16, 2011 3:38 pm

Ok. Ice Cold Air in Daytona Beach did a bang up job on the low pressure line. It comes straight up from the compressor, between the block and the header and then over to the shock tower. Short and secure. The thing blows very cold. Sense the a/c request wire isn't hooked up it drags down at idle and will probably stall if you let it. I just click it off or keep the revs up a little. Water temp going down the road is up by about 10 degrees. It's 93 ambient and going in stop and go, never over 45mph drive home the aftermarket temp guage sat at 190. I can live with that.Hood vents will drop that back down if needed.

Here's a fan question. I have the RH ron davis rad/ single fan combo. I want to plumb in another fan a la stk. GM. Should I use a pusher fan (aftermarket) on the front of the condenser as my #1 fan or redo the shourd and run a dual tarus style setup. Pro's or con's? I want to use the GM PCM to run everything.

Another question about sensors. Is the sole purpose of the high pressure input to the pcm to keep the system from over pressurizing? Is that likely? Also evaporator temp, why does the pcm want to see that? To prevent icing?

Obviously I'm trying to figure out what inputs I need to wire in and which ones I can live with out.Anybody been there and can help out?

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Re: A/C help needed

Post  acorad on Fri Sep 16, 2011 4:20 pm

Congrats on getting cold air! I'm officially jealous.

I am interested to see what you do about the idle revs while under AC load, as I'll have to cross that exact same bridge.

Why do you want to add another fan if you are OK with the rad temps as is?

My understanding is that the P computer disengages the AC clutch when the high-side sensor reads too much pressure in order to shut down the compressor and avoid icing. So the compressor constantly cycles on and off, 1980's style.

I believe the GM pcm wants to see evaporator temp because the GM compressor has a variable stroke and that stroke is controlled by the evap temp. The GM AC compressor never cycles on and off, it's always on (AC clutch is always engaged) after you push the AC button, 2000's-style. The GM pcm just reduces the stroke/output of the compressor when the evap temp gets too low in order to avoid icing.

I believe the GM evap temp sensor essentially replaces the P high-side pressure sensor in order to keep the system under control.

Did you disable the variable stroke in your compressor, or leave it stock?


Last edited by acorad on Fri Sep 16, 2011 4:39 pm; edited 1 time in total (Reason for editing : clarity)
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AC

Post  fliermike45 on Fri Sep 16, 2011 5:21 pm

I disabled the valve in the GM compressor so that the compressor will work a la Porsche. I have kept all the 944 system except that the GM computer will control the compressor on command from the Porsche AC request line. It should automatically increase the idle rpm when compressor is turned on.

I have to assume that the two switches on the drier/receiver will perform the safety functions in the system and cause the Porsche system to drop the AC request signal if required.

Can anyone confirm that this set up will work, I have not charged my system yet to test it.

There is a thread elsewhere on this site with info on modifying the valve.

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Re: A/C help needed

Post  sbwrench on Sat Sep 17, 2011 6:39 am


That explains why the pcm wants to see the a/c clutch and control it as well. I did not disable the variable stroke yet. I'm going to try to give the pcm all the proper inputs and see what happens. I want a fan to come on anytime the a/c is turned on, hence the need for a second fan. First thing to do is hook up the a/c request and see if that helps with the idle.

It sure is a different car with the windows up and the cold air cranking. Keep in mind it was "only" 93 out yesterday. We get long streches well above that although probably not much more this year. I want to make sure this system does what it's supposed to, when it's supposed to. It's going to take me a while to do it all. Lot's of other projects underway and a busy travel schedule but I'll keep after it.

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Re: A/C help needed

Post  acorad on Sat Sep 17, 2011 10:36 am

My system is set up basically the same as yours. RH rad and fan and simply wire the Porsche AC request over to the GM compressor and call it a day.

It should be pretty simple to wire the RH fan into the P AC request wire so that it comes on when the AC button is pushed.
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Re: A/C help needed

Post  acorad on Tue Sep 27, 2011 2:03 pm

Well, I have AC finally. R12, new V7 compressor converted to fixed-stroke, OEM condensor, RH temperature controlled rad fan.

Icy cold!

Last Friday was the hottest day since I've had it up and running, about 95F, and in stop and go around the town driving the temp needle was about in the middle of the gauge, so around 195-200F (w/o AC it's usually at the first thin hash mark, about 175F). Idle speed is not adjusted (higher) by the computer when the AC compressor engages, regardless, it seems to idle just fine with the AC on.

It is early yet, I've only really had one hot day that required AC since I got it working, but so far so good. Today will likely be hot enough to require AC.


Last edited by acorad on Tue Sep 27, 2011 5:02 pm; edited 2 times in total
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Re: A/C help needed

Post  sbwrench on Tue Sep 27, 2011 3:01 pm

Feels good, doesn't it? Way to go.

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Re: A/C help needed

Post  acorad on Tue Sep 27, 2011 4:57 pm

Thanks! It's so cold it makes my fingers hurt.
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