Wiring a R-4 A/C compressor - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sgaylord · 03-19-2009, 09:16 AM

I put a serpentine system off a 89 Chevy truck on my 69 CST-10. I am having difficulty trying to figure out how to wire the compressor. My 69 has factory air with only 1 green wire for the old A-6 compressor but the R-4 has 3 wires. 1 green (I assume this is where I would connect the green wire that previously connected to the old a-6 compressor), 1 black (I assume this is ground) green and black are connected on the front of the compressor, and 1 tan on the rear of the compressor (I have no idea where this one (tan)connects) . I know others have installed these before but I could not find anything in my searches for r-4 a/c compressor wiring, r-4 compressor wiring, etc. Can someone help me figure out how to wire this thing? I have included some pictures to show what I am talking about.

spinning wheels · 03-19-2009, 11:52 AM

I would just check the wiring on an '89 truck with that compressor.

Lugnut64052 · 03-19-2009, 03:04 PM

The green one does connect to your old green one.

The black one is a ground. I think the original setup had the black one grounding right to the compressor mount somewhere close. Your new setup will work fine if you do the same thing. Be sure you retain the diode across the green and black wires.

The switch on the back with the tan wire is a high side cutout. It's supposed to kill power to the compressor clutch in case the system pressure goes too high. The original A6 system did not have this feature, and the new R4 will come on and work fine without hooking it up. If you're using the original POA setup you might be able to get away with not hooking up the high side cutout.

However, if you're sort of "manufacturing" a new system, like installing one of those POA eliminators, or converting to a CCOT system, I'd hook up the high side cutout just to be on the safe side. Hunt up a wiring diagram for the '89 truck to see how it was wired.

sgaylord · 03-19-2009, 03:15 PM

Thanks lugnut64052 , I am using the stock POV setup with the pressure mod from 29 to 26 psi. Everything else is stock. Sounds like I should be ok then.

Thanks,
Steve

Lugnut64052 · 03-19-2009, 04:19 PM

Excellent. You should be good to go without using the high side cutout.

Chevy4Life · 03-20-2009, 09:54 AM

I'm in the process of doing the same conversion. I'm using a 91 serp. setup and it doesn't have the pressure switch on it. It's good to know both style r-4s can be used. Could you tell me more about your setup? Are you using the stock condenser? Where did you get the fittings and hose made? Can you take some pics of the evaporator and condenser hookups? I'd really like to hear how well it works. Post some vent temps if you can.

Thanks,
Jay

03-19-2009, 09:16 AM	#1
sgaylord Project collector Join Date: Mar 2006 Location: Sanderson, Fl Posts: 700	Wiring a R-4 A/C compressor I put a serpentine system off a 89 Chevy truck on my 69 CST-10. I am having difficulty trying to figure out how to wire the compressor. My 69 has factory air with only 1 green wire for the old A-6 compressor but the R-4 has 3 wires. 1 green (I assume this is where I would connect the green wire that previously connected to the old a-6 compressor), 1 black (I assume this is ground) green and black are connected on the front of the compressor, and 1 tan on the rear of the compressor (I have no idea where this one (tan)connects) . I know others have installed these before but I could not find anything in my searches for r-4 a/c compressor wiring, r-4 compressor wiring, etc. Can someone help me figure out how to wire this thing? I have included some pictures to show what I am talking about. Attached Images __________________ 69 CST-10 SWB (disguised as a 67) 383/700r4 Jezebel Jezebel 3.0 NEW!!! 2020 GMC 3500 Denali Duramax 2016 Harley Street Glide CVO Roll Tide! Last edited by sgaylord; 03-19-2009 at 02:50 PM.

03-19-2009, 11:52 AM	#2
spinning wheels Registered User Join Date: Sep 2001 Location: Hacienda Heights, California USA Posts: 474	Re: Wiring a R-4 A/C compressor I would just check the wiring on an '89 truck with that compressor. __________________ '72 GMC custom camper 350/350

03-19-2009, 03:04 PM	#3
Lugnut64052 Middle-aged Curmudgeon Join Date: Jun 2008 Location: Independence, MO Posts: 753	Re: Wiring a R-4 A/C compressor The green one does connect to your old green one. The black one is a ground. I think the original setup had the black one grounding right to the compressor mount somewhere close. Your new setup will work fine if you do the same thing. Be sure you retain the diode across the green and black wires. The switch on the back with the tan wire is a high side cutout. It's supposed to kill power to the compressor clutch in case the system pressure goes too high. The original A6 system did not have this feature, and the new R4 will come on and work fine without hooking it up. If you're using the original POA setup you might be able to get away with not hooking up the high side cutout. However, if you're sort of "manufacturing" a new system, like installing one of those POA eliminators, or converting to a CCOT system, I'd hook up the high side cutout just to be on the safe side. Hunt up a wiring diagram for the '89 truck to see how it was wired. __________________ Bret Check out the site's Truck Tech FAQ. Be a site supporter. My more-or-less pathetic build thread. Board members I've met: ------------------------------ Longhorn Man Dieselwrencher jholley big mike71

03-19-2009, 03:15 PM	#4
sgaylord Project collector Join Date: Mar 2006 Location: Sanderson, Fl Posts: 700	Re: Wiring a R-4 A/C compressor Thanks lugnut64052 , I am using the stock POV setup with the pressure mod from 29 to 26 psi. Everything else is stock. Sounds like I should be ok then. Thanks, Steve __________________ 69 CST-10 SWB (disguised as a 67) 383/700r4 Jezebel Jezebel 3.0 NEW!!! 2020 GMC 3500 Denali Duramax 2016 Harley Street Glide CVO Roll Tide!

03-19-2009, 04:19 PM	#5
Lugnut64052 Middle-aged Curmudgeon Join Date: Jun 2008 Location: Independence, MO Posts: 753	Re: Wiring a R-4 A/C compressor Excellent. You should be good to go without using the high side cutout. __________________ Bret Check out the site's Truck Tech FAQ. Be a site supporter. My more-or-less pathetic build thread. Board members I've met: ------------------------------ Longhorn Man Dieselwrencher jholley big mike71

03-20-2009, 09:54 AM	#6
Chevy4Life Senior Member Join Date: Feb 2003 Location: Las Vegas, NV Posts: 749	Re: Wiring a R-4 A/C compressor I'm in the process of doing the same conversion. I'm using a 91 serp. setup and it doesn't have the pressure switch on it. It's good to know both style r-4s can be used. Could you tell me more about your setup? Are you using the stock condenser? Where did you get the fittings and hose made? Can you take some pics of the evaporator and condenser hookups? I'd really like to hear how well it works. Post some vent temps if you can. Thanks, Jay



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