AC wiring - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Andy4639 · 02-11-2014, 06:08 PM

I have the AC working but not through the Computer. The new compressor doesn't have the connector for the wiring harness. Is there anyway to get this wired so the computer controls the AC?
Anybody done there this way before? The compressor is running off the fan switch out of the dash through the low pressure switch on the acumaltor which is hooked to the ground wire of the compressor. The 2 wire connector is just laying there not hooked up to anything. I tied it off to the bracket.

**Clyde65** · 02-11-2014, 07:23 PM

I have an old air system and it doesn't go through the computer either.

chuckmc8 · 02-11-2014, 07:38 PM

Andy, If its working now Id leave it alone. I remove the ac wiring from the LS harness and have the tuner remove the ac from the computer. As far as I know, all it would do thru the computer is bump up the idle when the ac is on, and Ive never had it be an issue with the ac not run thru the computer. Hope this helps

Andy4639 · 02-11-2014, 07:49 PM

Quote:

Originally Posted by chuckmc8

Andy, If its working now Id leave it alone. I remove the ac wiring from the LS harness and have the tuner remove the ac from the computer. As far as I know, all it would do thru the computer is bump up the idle when the ac is on, and Ive never had it be an issue with the ac not run thru the computer. Hope this helps

Yes it does. I thought it kicked the thing off when you got on it hard. If this isn't the case then yes I will leave it alone and put the plug back up into the wiring where it can't be seen. Thanks. I don't know where I got this idea but that is how I I always thought it worked.

ls1nova71 · 02-12-2014, 01:50 AM

When wired through the PCM, the compressor will be shut off at WOT. You would need both hiigh and low pressure switches in your A/C lines, then you would need to wire the fans to becontrolled by the PCM if they are not already. Then the fan control would need to be enabled in the tune to change the recirculate door wiring to fan controls. You would also need to wire in an A/C compressor relay to the clutch. Its doable, but if its worked the way it is in the past, I'd just leave well enough alone.

Andy4639 · 02-12-2014, 07:41 AM

Yea, that sounds like the thing to do. Just leave it as is.

**Hart_Rod** · 02-12-2014, 11:42 AM

Quote:

Originally Posted by Andy4639

Yea, that sounds like the thing to do. Just leave it as is.

+1! I'm mean 3,

chevyguy_72 · 02-13-2014, 10:44 AM

I thought I read somewhere there was a wire to connect the AC to the computer to bump up idle when the AC was running?

Custom 68 · 02-13-2014, 12:05 PM

Yes there is, I am sure his installer took care of it.
Mine is controlled by by normal dash switch but I "teed" into the "power" to the AC compressor to my computer so it will bump the idle when the AC is on. I need to bump it up some more it will still try to stall at times. Combined with the cam and now being a manual it seems to be a bit tricky to "catch" the idle quickly when the clutch goes in during a stop.

**dayj1** · 02-13-2014, 01:44 PM

Quote:

Originally Posted by chevyguy_72

I thought I read somewhere there was a wire to connect the AC to the computer to bump up idle when the AC was running?

Quote:

Originally Posted by Custom 68

Yes there is, I am sure his installer took care of it.
Mine is controlled by by normal dash switch but I "teed" into the "power" to the AC compressor to my computer so it will bump the idle when the AC is on. I need to bump it up some more it will still try to stall at times. Combined with the cam and now being a manual it seems to be a bit tricky to "catch" the idle quickly when the clutch goes in during a stop.

There is an A/C request input, but it's not a simple as hooking up a single wire. To gain the computer control, you have to wire in the correct pressure sensors etc as ls1nova71 mentioned above or the ECM just ignores the A/C request.

For what it's worth, the aftermarket Sanden compressors or the stock Gen III/IV compressors don't take a lot of power to turn. In my opinion, it's not even worth the added hassle for the ECM control because they just don't load the engine enough to matter.

Andy4639 · 02-13-2014, 02:31 PM

I was told not to worry about it and run it as is. That's how I plan to roll! Will see how it does this summer and go from there.

Custom 68 · 02-13-2014, 04:21 PM

Quote:

Originally Posted by dayj1

There is an A/C request input, but it's not a simple as hooking up a single wire. To gain the computer control, you have to wire in the correct pressure sensors etc as ls1nova71 mentioned above or the ECM just ignores the A/C request.

For what it's worth, the aftermarket Sanden compressors or the stock Gen III/IV compressors don't take a lot of power to turn. In my opinion, it's not even worth the added hassle for the ECM control because they just don't load the engine enough to matter.

You are correct and I may not have stated it clearly. I do have a single wire that knows when I turn on the AC and it bumps the idle up. It does not have any control over the AC compressor itself. So it wont cycle the AC or turn it off if I go wide open or any of that. It is just used to bump my idle. I can control how much with HP tuners.
Dave

Jonboy · 02-13-2014, 04:56 PM

Andy, the wire that is powering your Sanden compressor- is that the green wire that went to the original compressor?

Andy4639 · 02-13-2014, 05:55 PM

Quote:

Originally Posted by Jonboy

Andy, the wire that is powering your Sanden compressor- is that the green wire that went to the original compressor?

Yes, just like it was before the swap. I ran it coming home the other night from Hawks but really didn't pay it much attention as to it idling up are anything. I was to worried about how the motor sounded with the new exhaust! It got cold though!

02-11-2014, 06:08 PM	#1
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	AC wiring I have the AC working but not through the Computer. The new compressor doesn't have the connector for the wiring harness. Is there anyway to get this wired so the computer controls the AC? Anybody done there this way before? The compressor is running off the fan switch out of the dash through the low pressure switch on the acumaltor which is hooked to the ground wire of the compressor. The 2 wire connector is just laying there not hooked up to anything. I tied it off to the bracket. Attached Images __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-11-2014, 07:23 PM	#2
Clyde65 1965 Chevy C10, 2005 4.8L/4l60 Join Date: Aug 2004 Location: DFW Texas Posts: 8,546	Re: AC wiring I have an old air system and it doesn't go through the computer either. __________________ Clyde65 Rebuild of Clyde http://67-72chevytrucks.com/vboard/s...84#post8338184 69 Aristocrat Lo Liner build http://67-72chevytrucks.com/vboard/s...84#post7561684 *support our troops!*

02-11-2014, 07:38 PM	#3
chuckmc8 It's alsways something..... Join Date: Nov 2008 Location: Douglasville GA Posts: 1,171	Re: AC wiring Andy, If its working now Id leave it alone. I remove the ac wiring from the LS harness and have the tuner remove the ac from the computer. As far as I know, all it would do thru the computer is bump up the idle when the ac is on, and Ive never had it be an issue with the ac not run thru the computer. Hope this helps __________________ 1968 RS Camaro 'Vert Matching number 327 and M21 Muncie 1968 C10 Black with red interior and orig paint. 5.3 / 4l60e,3:73 POSI 17" Torq Thrusts 1968 CST 514 Red with black interior. Buddy Buckets, Factory A/C, PS, PB- 20" AR custom shop TT, 5.3 and 4l60e

02-12-2014, 01:50 AM	#5
ls1nova71 Registered User Join Date: Dec 2009 Location: Independence Mo Posts: 4,118	Re: AC wiring When wired through the PCM, the compressor will be shut off at WOT. You would need both hiigh and low pressure switches in your A/C lines, then you would need to wire the fans to becontrolled by the PCM if they are not already. Then the fan control would need to be enabled in the tune to change the recirculate door wiring to fan controls. You would also need to wire in an A/C compressor relay to the clutch. Its doable, but if its worked the way it is in the past, I'd just leave well enough alone. __________________ My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html

02-12-2014, 07:41 AM	#6
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: AC wiring Yea, that sounds like the thing to do. Just leave it as is. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-13-2014, 10:44 AM	#8
chevyguy_72 Vintage Evil Join Date: Aug 2005 Location: Hastings, Nebraska Posts: 956	Re: AC wiring I thought I read somewhere there was a wire to connect the AC to the computer to bump up idle when the AC was running?

02-13-2014, 12:05 PM	#9
Custom 68 Registered User Join Date: Nov 2001 Location: Springfield, MO Posts: 2,939	Re: AC wiring Yes there is, I am sure his installer took care of it. Mine is controlled by by normal dash switch but I "teed" into the "power" to the AC compressor to my computer so it will bump the idle when the AC is on. I need to bump it up some more it will still try to stall at times. Combined with the cam and now being a manual it seems to be a bit tricky to "catch" the idle quickly when the clutch goes in during a stop. __________________ Dave 1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap 1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?) "A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome". "If it doesn't fit force it...If it breaks then it needed to be replaced anyway!"

02-13-2014, 02:31 PM	#11
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: AC wiring I was told not to worry about it and run it as is. That's how I plan to roll! Will see how it does this summer and go from there. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

02-13-2014, 04:56 PM	#13
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: AC wiring Andy, the wire that is powering your Sanden compressor- is that the green wire that went to the original compressor? __________________ 1974 Jimmy- 5.3/4L80e/NP241



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