The last task in doing my 3800SC swap was to get the A/C working. We are using a 2006 GTP compressor and piping it in is a plumbing job. We can possibly have the line made by NAPA or an outside source.
In looking into 3800SC swaps further, it was pointed out that the 2006 GTP A/C compressor is a variable displacement type. As such it needs no cycling switch and is under PCM control . The 3800SC has three inputs /outputs on the PCM. An A/C request signal input ( believe this to be 12V from the Fiero A/C switch) , an A/C relay output ( drives the A/C relay to energize the clutch) and most importantly an A/C pressure control switch input (takes inputs on line pressure and provides the signal to the PCM) which tells the PCM how to control the A/C system..
Now if these assumptions are correct it should be a simple wiring job to get the A/C operational. However, the question of how and where to locate the A/C line pressure switch is the most difficult to solve. This was discussed on a post a few weeks ago and the suggestions ranged from welding in a fitting to the high pressure side to instaling the switch on the high pressure port near the accumulator. For those that have already got the GTP system working; comments on the above would be appreciated. We've got a couple of these to do and want to do the job correctly the first time.

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87GT - with 3800SC Series III engine, 4T65eHD
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

For swaps I have done where the PCM got control of the A/C I got the lines from a car at the wreckers that had the three pin pressure sensor in them near the compressor and used these lines to be made up to attach to the Fiero lines. I got an A/C shop to just combine the two lines with proper crimps and every thing worked out fine.
I can't remember for sure which 3800 engine I got the A/C lines from though but if you search a wreckers you will find a set with the sensor in them. Dan

I hate the wreckers around here, one charges a min of $30 even if its a tiny wire connector, one is so dangerous I almost die everytime.

If you could remember the type of car with the 3 pin I would be most appreciative Dan.

I have to get my 3800 hose asap, as I have already wired in the 2 front relays in the front and the one by the fuel relay in the back.

I assume the wires from the a/c relay in the back will connect to this sensor?

quote Originally posted by Matthew_Fiero: There is currently two wires coming from the compressor, a green and a black. They get connected..where?

Green wire goes to contacts of the A/C relay. Black wire goes to ground or low reference. A/C relay coil is activated by the PCM . A/C relay output turns on when a request signal is sent to the PCM by your A/C switch. Line pressure switch controls the A/C cooling function and its looking more an more like a fitting needs to be welded in so that we can install this. .

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87GT - with 3800SC Series III engine, 4T65eHD
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 05-02-2008).]

Added this to my thread list... Lets see some pictures and answers in here, I have yet to set up a/c myself, and interested in what this switch looks like when it is installed.

I got my comp put of a 96 regal and i saved the switch and a piece of the pipe that the switch attached to. so i wanted to splice the pipes together and the make splices with a/c fittings on them but the switch needs a switch port and i could not find a splice with a switch port on one. so i had the right port cut off the old regal line and welded onto the splice that i got from napa then had them crimp the lines together for me. when we crimped them we found the the splice that fits the inside of the hose is way big for the outside of the gm hoses so we had to double crimp them, we started with the right crimp die for the fitting then recrimped with the next size down and the seem real tight, we could not move them at all so i think they are going to work. i hope to put them on this weekend and i'll let you know more then.

the part number for the switch i have is 22571286 (number on the switch)
I checked with the gm supplier i deal with they had a part number 15-5742 listed
Hope this helps

btw how can i post pics so you can see what i did?

Ant

wow, how come no one else really has encountered this problem? I thought the switch on the accumulator can be used instead??

quote Originally posted by Ants87gt: I got my comp put of a 96 regal and i saved the switch and a piece of the pipe that the switch attached to. so i wanted to splice the pipes together and the make splices with a/c fittings on them but the switch needs a switch port and i could not find a splice with a switch port on one. so i had the right port cut off the old regal line and welded onto the splice that i got from napa then had them crimp the lines together for me. when we crimped them we found the the splice that fits the inside of the hose is way big for the outside of the gm hoses so we had to double crimp them, we started with the right crimp die for the fitting then recrimped with the next size down and the seem real tight, we could not move them at all so i think they are going to work. i hope to put them on this weekend and i'll let you know more then. the part number for the switch i have is 22571286 (number on the switch) I checked with the gm supplier i deal with they had a part number 15-5742 listed Hope this helps btw how can i post pics so you can see what i did? Ant

Ant: To post pictures here join a free images hosting service like Photobucket or Solis Image share. Load the images from your computer to the hosting site and them post the image location here between [img] image location address here [/img]. The image will come up in the post.

Like I said, can't the pressure switch on the accumulator just be used instead? would save all this splicing, i wouldn't even know where to get a T like that!!

quote Originally posted by Matthew_Fiero: Like I said, can't the pressure switch on the accumulator just be used instead? would save all this splicing, i wouldn't even know where to get a T like that!!

That depends on the compresser that you use mine is a V5, the pressure switch that the fireo has from the factory is a low side clutch cycle switch. it is used to cycle the clutch when the pressure drops below about 28 psi that is how they control the system and keep it from icing up. the newer v5 compresser varies its displacment to regulate pressure and therefore do not use a low pressure cycling switch so that is why you need the switch that i have so that the ecm can control the a/c. it will stop the system from coming on when the system is low or if its to high. also the ecm needs to know when the a/c is on so that it can control the idle.

as for the fitting that i used any Napa can get it for you or any shop that can crimp a/c hoses, the only problem is that the fitting is differant and that is why i had mine welded using the fitting (threaded part) from the regal and the slice that i got from napa.

Ant

[This message has been edited by Ants87gt (edited 04-30-2008).]

The compressor I am using is from a 98 GTP. I just looked and did not see any markings on it pertaining to any V series.

It says part number 1135238, is this a V5?

I am getting very confused now.. If the T is actually necessary or not.

quote Originally posted by Matthew_Fiero: The compressor I am using is from a 98 GTP. I just looked and did not see any markings on it pertaining to any V series. It says part number 1135238, is this a V5? I am getting very confused now.. If the T is actually necessary or not.

You should have a v5 compresser, so you need the same pressure switch that i have it goes into the high side hose on you a/c system you can put it anywhere that you want to in the high side.
Ant

So let me get this straight so I can work on this tomorrow.

I need my Fiero Line, which I have, which will be spliced to accommodate the GTP Compressor, so a GTP line spliced into it. As well as the regal fitting which will be welded in between the GTP side and Fiero Side.
The switch will also be from the regal and is 3 pin..

Right?

Yes yoy will no longer need the pressure switch that is up front.

I have not called these guys but you might see what they have
www.classicautoair.com
they some fittings like i got they may even have the right service port.
anyway probably worth the call

Ant

I found a a/c line today that stuck right out of the fitting that goes into the compressor!!! No idea what it came out of, it was just laying in a pile at the yard.

Pictures later.

did it have the 3 pin sensor still in it?

bump

This is the same setup that was on my DOHC. I installed a fitting into the high pressure line near the compressor for the pressure sensor. The only issue I had was I am not sure I ever got the correct fitting for the switch. The inside of my switch looked like it had a tapered seat of some sort and I don't think I ever found the correct fitting for that seat. However an old T adapter I had for the high side port up front looked like it did have the correct seat.

If you put the sensor in the high side near the compressor then all the wiring is back there. If you put the sensor up front then you'll have some wires to run. The only think I'd be careful about is that the fitting you use to mount the sensor fits correctly or you'll have a bugger of a time getting it to seal !

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Dave

www.ltlfrari.com

Exactly! That is what I am worried about, finding the correct sensor AND the correct T fitting..

quote Originally posted by Matthew_Fiero: Exactly! That is what I am worried about, finding the correct sensor AND the correct T fitting..

Hang in there men, we'll find a solution. It appears that we will need a custom made inline T fitting to put the high pressure switch on the high side line. I'm going to look in the Four Seasons catalog tomorrow to see if they have anything standard If not, its back to the boneyard.

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87GT - with 3800SC Series III engine, 4T65eHD
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by darkhorizon: I found a a/c line today that stuck right out of the fitting that goes into the compressor!!! No idea what it came out of, it was just laying in a pile at the yard. Pictures later.

Wouldn't it be easier to install a binary switch at the high side service port? You could use the wiring from the unused cycling switch to route the signal to the computer. The only problem with this approach is that a blockage in the condenser or high side line ahead of the service port would not be detected. But the most likely place for a blockage is at the orifice tube screen which would be detected. If debris from the compressor was large enough to block a line or condenser, the high/low pressure cut off switch wouldn't save it any how.

Here's an example of the switch kit:



Low - High pressure Cut-off Switch

Fits 3/16" R12 Service Port -Steel 1/4" Female Switch Port with 16 MM Charging Port - Binary Pressure Switch - Low opens at 28 PSI - High opens at 384 & closes at 256-340 PSI - Red Service Cap - Wiring Harness and Switch Adapter

$39.17 at Arizona Mobile Air

Interesting idea..
ok we ARE getting somewhere


Could the switch mounted to the accumulator/dryer be used for the high pressure T fitting?

What is the size of the tubing for the high side, so I know what to tell some shops when I'm looking for one..

Matt

The Grand Prix 3800 uses a high pressure sensor on the A/C high line and not a high pressure switch. This sensor signal is sent to the PCM and I believe is used as the input signal which allows the PCM to control the cooling as a function of a resistance which varies with the line pressure. With the GTP A/C system you don't use a compressor cycling switch but PCM control of that system.

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87GT - with 3800SC Series III engine, 4T65eHD
87GT - 3.4L Turbocharged engine, modified TH125H
" I'M ON THE LOOSE WITHOUT THE JUICE "

Interesting.. I now understand its a sensor.

I have a 4cyl a/c hose in the backyard and I noticed it has a T fitting on it, think this could be useful?

bump

Nevermind.. the A/C shop must have closed up, it is now a restaurant.

Some salt on that? Perhaps some freon?
Maybe they serve an R-12 Burger or the 134Angus burger...

[This message has been edited by Matthew_Fiero (edited 05-10-2008).]

quote

I think this is the same T piece I had and was considering using. I 'think' the sensor will mate correctly to this, at least tit looked that way on my DOHC, your milage may vary !

Just out of curiosity, how would you attach that to the a/c line?

It goes on the high side a/c port up front.

one of the fill points?

who needs a T when you can do this?