calling out to people who have converted their 68-72 a body gm with ls1 and used the ls1 a/c compressor along with the factory (68-72) hvac system on car.

looks like we can make some custom hoses and wire up an electric fan. then be good to go? looks like the factory throttle suction valve will allow the compressor to run non stop w/o a cycling switch. the transplant came from an ls1 gto. looks like it (compressor) was pcm controlled based on high side pressure. can that compressor work well in that environment?

anybody done one like this? the way i'm talkin about? how did it work?

 

This is my next undertaking. 69 GTO with factory AC, using the original GTO controls and a truck compressor. I will be charging in blindly, hopefully the input you get here will help me as well.

 

I have all Chevelle OEM with the exception of the LS1 Compressor and custom lines to mate the two system together..

I just used the Chevelle's Green wire and spliced into the LS1 harness and since I have a standalone SPAL Fan controller, I also wire that green wire into the controller AC / Manual terminal.

One item you need to be aware of is that some of the Gen III/IV compressor are variable displacement and somre or not. I know the 4th gen LS1 Fbody was variable, which would make the Chevelle system run at 60% capacity.

I am no expert on AC, but it does work ok most of the time. A better Condensor that would be for R134a would make the system better and a non-variable compressor also.

BC

 

The variable compressor can be made to be a fixed compressor by taking the valve out and either welding the tip shut or removing in the O-ring. The system will need a pressure valve to control the compressor clutch, the original car's system probably had this.

 

the donor is an 04 GTO. here is the description for this compressor from alldata


Compressor
The Delphi V7 compressor can match the air conditioning demand under all conditions without cycling. The basic compressor mechanism is a variable angle wobble-plate with 7 axially oriented cylinders. The compressor has a pumping capacity of 179 cc.

The control valve is installed in the compressor rear head. The wobble-plate angle of the compressor, and the resultant compressor displacement, are determined by the compressor crankcase to suction pressure differential which is governed by the control valve.

When the A/C capacity demand is low, the crankcase pressure behind the pistons is equal to the pressure in front of the pistons. This forces the wobble plate to change its angle to towards vertical which reduces the stroke of the pistons and reduces the output of the compressor to approximately 14.5 cc. The evaporator cooling load is reduced, ambient temperature or blower fan speed is reduced, and therefore, the suction pressure is reduced until it reaches the control point.

To reach the control point, the bellows in the control valve assembly has expanded to allow discharge pressure to bleed past the control valve ball valve seat and into the compressor crankcase. This crankcase pressure acts as an opposing force behind the compressor pistons to cause the wobble plate to change its angle towards vertical and therefore, reduce piston stroke.

When the A/C capacity demand is high, the crankcase pressure behind the pistons is less than the pressure in front of the pistons. This forces the wobble plate to change its angle away from vertical which increase the stroke of the pistons and increases the output of the compressor to approximately 164 cc. When suction pressure is above the control point, it will compress the control valve bellows. This will close off the discharge valve as the ball valve is now on its seat. The shuttle valve moves towards the suction port and opens the suction valve. Crankcase pressure will then bleed from the compressor crankcase past the suction valve to the suction port. As the crankcase pressure behind the pistons is reduced, the wobble plate will tilt from vertical causing the pistons to move towards maximum stroke. The compressor will then have a corresponding increase in its displacement.



so do we hook it up and see how it does? or do we need to modify or replace the compressor?

 

It depends on how you want to run the compressor. If the original computer is going to run it with all of the sensors set up like the original system then you don't have to modify the compressor at all. The 2004 GTO PCM did not control the AC input, the body control module did. So, unless you have the BCM, you are probably going to have to modify the compressor to work with the cars pressure valve system.

 

what is that?

 

we do not have the bcm. can we just use the vehicles wiring to turn on the compressor? use the same ckt to trigger an ac request in the pcm some how? and let the pcm control the fan? or just set up an ac fan relay ckt and just have it on at all times with the ac since there will not be a high side pressure switch?

 

The problem is the GTO PCM does not have AC request and, to my knowledge, there isn't a proven way to get it to be programmed in. There have been ideas thrown around but no one can confirm it. I have my system working off of the cars system triggering the compressor without the PCM seeing anything.

 

well got it all hooked up and charged. the high side pressure is a little low. and the output is cool at the vent. but not as cold as it could be. so what can we do about the compressor again? how is that done?

 

This is an older thead about that subject has links to how it's done.

https://ls1tech.com/forums/conversio...ble-fixed.html

Let us guys who have not done it yet know how it works out.

 

I am still running the Variable F-Body compressor.. as long as I am moving, I can get it down to 48-50 drgee at the vents.. but if stuck in traffic it goes up to 55-56 degree. I am use that there is something else that I could do to.. I think I could use a better Condensor.. one that is sized for R134a...

A while ago. I checked the pressure and thought it was a bit high. I let some gas out and down some PSI on the low side.. It help as the air temp coming out of the vent was a few more degree cooler. So I know there could be some tweeking, but I am no expert to this.. but I am good with what I have...

BC

 

A 04 GTO setup will work without the BCM by using the A/C request and fan setup wired the same as a 02 411 PCM. NO BCM NEEDED. I believe there is one or two switches that need to change OS but that is it. People say you need the BCM and cannot use a normal 12 volt A/C request to work along with one of the fans only because that is how a GTO is wired and that is what they are going by. There apparently is a difference between a 243 and 242 PCM where the 243 works and the 242 does not because the 242 was never used in cars or trucks that have a 12 volt A/C request.

There is also a lot of mis information on the use of variable compressors versus a fixed compressor when converting systems. The main thing that you need to do is configure the A/C system to run 134 as opposed to Freon 12 if you are using a combination of old and new. The older systems should be converted to a 134 by replacing the condensor to a 134 type and the valve. For GM's it would be best to convert the valve to an orifice type (POA) and use the proper orifice tube. Classic auto air has some converstion stuff where they will recalibrate the Suction Throttle Valve (STV) for 134 but they do not say you need a new condensor. This is needed to increase the low pressure side for 134. I am using a vintage air setup with a variable compressor with no problems and it runs cold at idle as well as at speed.

 

what ur engine temps running in hot weather? Thats been my concern running a AC unit

 

Running thru your neck of the woods (Burleson) on my way home every day in 106 -107 degree weather mine has been bumping 210 degrees in traffic.

 

I don't run hot but I am by the coast. I do have similiar temps but it is more fan related in stop and go traffic. I am using a stock radiator and fans but the temp has been programmed to turn the fans on at lower temps.

 

I'm running a LT1 Rad and using a Manual switch for my fans, I remember last year my car hit 220 sitting in stop and go traffic so thats why im concerned about running a AC unit

 

Well if U ever see and dude on a red 1198 Ducati thats me

 

Are you the guy who passed me at Renfro doing a wheelie @ 90 mph standing on the left peg with the right foot. Left foot and arm hanging in the wind shooting the trigger finger at Burlesons finest (north bound) and did not drop the front wheel back to the ground until the 917 exist in rush hour traffic? If so

 

lol, im not a squid and I can bet money that wasnt a Ducati Mostly older guys with some common sense ride these machines