Need help connecting my a/c compressor.

Does anyone know the size of the hoses and fittings needed to connect a LS truck compressor to the rest of the system on an OBS truck? I planned on using the peanut style compressor blocks from here,Sending Unit Wizard, and just get the hoses made but I need to know the sizes for the fittings at the evaporator and condensor and also what fittings would have to be built into the hose for charging the system.

Sorry for all the questions, I'm not really familiar with a/c's since i haven't had one in the ten years i've been driving lol.Thanks

Are you able to simply drive it over to a A/C hose shop & have them make them up? They are generally quite affordable to have them make them, even at a drive up shop. Less than $40.00 & your good to go. But...If your in a rural area, that might be a problem.

I thought about that but theres not really any shops around here that specialize in a/c services.

I think I may have the hoses figured out but does anyone know how to wire the system? Should I use the wiring from the old harness and just wire on the pigtail for the new compressor? or does the LS compressor have to be operated by the new PCM? and if so how do I incorperate my original controls?

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Originally Posted by low91

I think I may have the hoses figured out but does anyone know how to wire the system? Should I use the wiring from the old harness and just wire on the pigtail for the new compressor? or does the LS compressor have to be operated by the new PCM? and if so how do I incorperate my original controls?

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NITROUS! Where are you? He knows this A/C stuff, on our trucks. Let me try to remember. You have a A/C request wire that comes from your dash control. This gets wired to one side of your two-wire low pressure switch thats on your accumulator on the firewall. The other wire from the accumulator switch connects to your A/C request wire coming from your computer. Also from the computer, is a wire that activates the relay, that cycles the compressor on & off. You should also have an A/C sensor plug/wire coming off the harness, that plugs into a hi-pressure side sensor that should be intalled on the hi-pressure side hose somewhere. RedHeartBeat knows this **** too.

Lol yeah I had hoped Nitrous would chime in. I remember he kept the LS A/C comp.

I got my compressor fittings in and it looks like theres no way I'll be able to use the compressor in the factory location the lines come out right into the forward a-arm mount. Does anyone know of a bracket that would move the stock compressor up top? If not, would I wire a Sanden compressor the same way stated above?

low91, post a pic of your setup so we can see which way you need to go. There's plenty of options, I just need to see your current configuration but the F-body compressor fittings will eat you alive since they come out of the back of the comopressor. I have a small hitachi compressor that would probably work great but I need to get the numbers from work Monday. I used the 2002 F-body HP switch and it's installed behind the grill on the condenser. If I remember correctly pin 17 on th pcm goies to the relay and pin 18 goes to the clutch. The green wire from the relay will go to the LP switch. The HP switch grey wire goes to pin 45 which should be the 5 volt reference for refrigerant pressure. I believe the high pressure switch actually has 3 wires which are black (ground) grey (5 volt reference) and red/black (refrigerant pressure signal). This is the switch to the PCM that's tied to your DTC's. The Low pressure switch could actually just go to the clutch to kick it on and off based on pressure demand.

BTW, I just pulled this out of memory so I might need to look at my notes if I gave you the wrong pin numbers.

If I could just find the smaller fitting in a forward 90* I think I could maybe make it work, it would be a tight fit. I really want to try to keep the comp. where its at, I hate the idea of that huge notch being empty:(


http://i214.photobucket.com/albums/c...Picture019.jpg

http://i214.photobucket.com/albums/c...Picture020.jpg

http://i214.photobucket.com/albums/c...Picture021.jpg

We need to find you a fitting that directs the hoses to the front of the vehicle instead of the side. Let me look and see what we can find you.

See how my hoses are facing forward out of the block and 90 out of the fitting back to the drier and go forward to the condenser.
http://i33.photobucket.com/albums/d7...g?t=1240697848

Docs Blocks is your best bet with the 90 on the fitting like this.
http://www.docsblocks.com/prodimages/AA1433.jpg

Your other option is to go with a 99/2000 compressor with my type fitting.
http://www.docsblocks.com/prodimages/AA1772.jpg

This helped me too, thanks.

That 90* fitting still may not clear the mount, it would have to be tweaked a little which could turn out bad since its aluminum. If all else fails I guess I can just go with the older compressor.

Also I'm reworking a DBC harness to replace my DBW setup that I have now. What,if any plugs of the A/C system can I get rid of ?

I was told that I can do without these:
Secondary A/C highpressure switch
A/C request signal
A/C clutch relay control
A/C comp. cycling switch signal

That would leave only:
A/C refrigerant pressure sensor signal
A/C comp. clutch supply voltage

Does that sound right?



I found this fitting on docs blocks but it is for the suction side. They have one for the discharge side but the tube comes out of the side. I'm going to email them and see if I can get this fitting in the smaller size.
http://i214.photobucket.com/albums/c...285/AA2210.jpg

We could always modify the fitting. I had to machine down my aluminum block for more clearance when the motor torques down on the passenger side.