Stock air conditioning with LS swap

[short-t]

Is anyone here using the factory ac their truck came with? I am to the point where I need to start making plans for the ac and where to put this trinary switch that the pcm uses to control the fans and ac compressor..

Any help or pictures would be much appreciated.

[Gordonr1973]

Read Glock's build.

Specifically around post #656 & 1309

[short-t]

Originally Posted by Gordonr1973

Read Glock's build.

Specifically around post #656 & 1309

Already read through his build, the ac on his 85 is a bit different than the 68, which I forgot to mention.

[clinebarger]

Are you dead set on keeping the Expansion valve/ POA valve/ Receiver Dryer system? It would be cheaper & easier to replace the Evaporator core with a fixed orifice style evaporator (Ive found 77 Olds 98 evaporators fit the best) & run a Accumulator & Orifice tube.

What year/make/model did your LS come out of? GM put the high side trinary in different places, sometimes in the discharge side, sometimes in the liquid line.

[short-t]

Originally Posted by clinebarger

Are you dead set on keeping the Expansion valve/ POA valve/ Receiver Dryer system? It would be cheaper & easier to replace the Evaporator core with a fixed orifice style evaporator (Ive found 77 Olds 98 evaporators fit the best) & run a Accumulator & Orifice tube.

What year/make/model did your LS come out of? GM put the high side trinary in different places, sometimes in the discharge side, sometimes in the liquid line.

I am open to suggestions on what is going work the best and for the least amount of $$. That is why I was going to keep the original equipment. Do you have any pics of a 68 with this type of system installed?


The engine is from a 2007 Trailblazer SS LS2. The ac compressor is a Denso 10S17F from a 2005 Silverado 5.3.

Thanks, Greg

[TR65]

Short-T,

I am in the process of installing a vintageair evaporator in my 65 but I am trying to use the ECM to control the fans and the AC clutch like you are. I have a 2005 LS2 from an SSR (E40 ECM).

What it uses is a pressure transducer that the ECM uses to protect the compressor in case of over or under pressure. Then it uses the pressure values to determine when no fan, 1 fan, or 2 fans need to run. There are tables in the ECM that you can modify if you want.

So I bought the pressure transducer from GM and an adapter from Doc's Blocks and I am going to aluminum braze it in the compressor discharge line. I am using the stock LS2 Sanden scroll compressor that came with the engine.

That is the last part of my AC install so not quite finished.

TR

[short-t]

Originally Posted by TR65

Short-T,

I am in the process of installing a vintageair evaporator in my 65 but I am trying to use the ECM to control the fans and the AC clutch like you are. I have a 2005 LS2 from an SSR (E40 ECM).

What it uses is a pressure transducer that the ECM uses to protect the compressor in case of over or under pressure. Then it uses the pressure values to determine when no fan, 1 fan, or 2 fans need to run. There are tables in the ECM that you can modify if you want.

So I bought the pressure transducer from GM and an adapter from Doc's Blocks and I am going to aluminum braze it in the compressor discharge line. I am using the stock LS2 Sanden scroll compressor that came with the engine.

That is the last part of my AC install so not quite finished.

TR

That should work, the switch you are talking about is a trinary switch. Gives the ok to the ecm for the compressor to come on and controls the sencond fan when pressures get to high within the system.

I've been trying to find this adaptor for my stock GM trinary switch, would you mind sharing the pn for it? Thanks, Greg

[TR65]

Short-T,

Here is the part:

http://www.docsblocks.com/products.asp?cat=20

Product ID: AC0146
Round Stock, Aluminum Refrigerant Valve 134A-standard flow Details

M10 x 1.25 Thrd switch port, .280 base
Price: $1.57

And you need a R134 schrader valve and -6 o-ring.

Here is a Pic of the whole rig including pressure transducer.

TR

[short-t]

Thanks TR! I look all over Docs Blocks and didn't see that...

I went through your build and love the work you have done. Must be a pleasure to drive and show off at the show's. How do you like the way the LS2 performs?

Greg

[TR65]

Originally Posted by short-t

Thanks TR! I look all over Docs Blocks and didn't see that...

I went through your build and love the work you have done. Must be a pleasure to drive and show off at the show's. How do you like the way the LS2 performs?

Greg

Short-T,

Yea, I looked thru Doc's several times, and ordered the wrong one once before I found it. Then it is $1.57. I paid more than that for WhopperJr for lunch today.

Thanks for the kind words. The LS2 is better than I imagined it would be. Starts every time, idles perfect in all conditions, completely docile until you open it up, then hold on. It has been dead reliable since I started it last July. Loves to cruise at 75. Daily driver.

TR

[87chevy.com]

I wired the a/c up without that switch... only things i have in the circuit is the low psi switch and the compressor clutch, and a/c relay... operates like it should from facotry with the ecm controlling the a/c relay.
clint

[TR65]

Short-T,

I brazed that adapter into my high pressure line today and fabricated the compressor block. Looks like it will work OK.

TR

[short-t]

TR, looking good! Are you using the ac compressor that came with your engine? If so I'd like to know how you mounted it to the engine after replacing your oil pan?

Keep up the great work!
Greg

[TR65]

Originally Posted by short-t

TR, looking good! Are you using the ac compressor that came with your engine? If so I'd like to know how you mounted it to the engine after replacing your oil pan?

Keep up the great work!
Greg

Thanks Greg,

Yep, I am using the OE compressor. The mounting was a real ordeal, so bad I don't even have any good pictures. So as you know, the truck oil pan doesn't have the two lower compressor mounting holes. I spaced out the compressor with 5/16" spacers on the top block mounting holes. That gave me room to bolt a 5/16" aluminum plate to existing block mounting holes and provide holes for the lower compressor mounting bolts, I put nuts on them. It also took some clearance machining on the compressor mounting cradle and the compressor itself. Moreover, I need that 5/16" for frame clearance. I also had to cut a access hole in the crossmember to reach the lower rear compressor mounting bolt. So far I have not had to cut the frame for clearance, that is my goal.

I am determined to use the low mount compressor. So, I hope all the above works.

The pic below shows some of it.

TR

[87chevy.com]

interesting.. I used the factory 5.3 a/c compressor and mount, and didnt have to space anything out. My compressor has a different manifold, a 2 seperate hose set. none the less the a/c works awesome... easily hits 50* out the vents . I charged my system to 2.25lbs.
clint

[short-t]

Originally Posted by TR65

Thanks Greg,

Yep, I am using the OE compressor. The mounting was a real ordeal, so bad I don't even have any good pictures. So as you know, the truck oil pan doesn't have the two lower compressor mounting holes. I spaced out the compressor with 5/16" spacers on the top block mounting holes. That gave me room to bolt a 5/16" aluminum plate to existing block mounting holes and provide holes for the lower compressor mounting bolts, I put nuts on them. It also took some clearance machining on the compressor mounting cradle and the compressor itself. Moreover, I need that 5/16" for frame clearance. I also had to cut a access hole in the crossmember to reach the lower rear compressor mounting bolt. So far I have not had to cut the frame for clearance, that is my goal.

I am determined to use the low mount compressor. So, I hope all the above works.

The pic below shows some of it.

TR

Good idea! I wish I had seen this before going out and getting a truck compressor and bracket. I would have like to use the compressor that came with the front sump oil pan because the ports are clocked higher than the truck ones. Do you know anyone that needs a ac compressor and bracket? LOL!

Nice job on the switch fitting, I ordered mine last week so its hurry up and wait!

Greg

[CamaroChris]

Thanks for the info guy's. I have a 01 harness and pcm. What pins do I need to add to the pcm to add electric fans? I want the fans to turn on with the a/c
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[67C10BUB]

Originally Posted by 87chevy.com

I wired the a/c up without that switch... only things i have in the circuit is the low psi switch and the compressor clutch, and a/c relay... operates like it should from facotry with the ecm controlling the a/c relay.
clint

That's how I did mine as well. I used the stock 5.3L compressor with the Old Air system and it looks and works great. Old Air is nice because you can buy a kit that doesn't include the compressor, condenser, or hoses and save some $$$.

[TR65]

Originally Posted by 67C10BUB

That's how I did mine as well. I used the stock 5.3L compressor with the Old Air system and it looks and works great. Old Air is nice because you can buy a kit that doesn't include the compressor, condenser, or hoses and save some $$$.

Do you guys run electric fans? If so do you have them turn on when you run the AC?

You can also just buy the evaporator unit from Vintageair. That is what I did.

By the way. It is not a switch. It reads the high side pressure. Then in the tune you have tables that allow you to turn one fan on and off at one set of pressures and a second fan on and off at another set of pressures. Keeps the fan use to a minimum. Of course the system would run fine without that.

TR

[clinebarger]

Originally Posted by TR65

Do you guys run electric fans? If so do you have them turn on when you run the AC?

You can also just buy the evaporator unit from Vintageair. That is what I did.

By the way. It is not a switch. It reads the high side pressure. Then in the tune you have tables that allow you to turn one fan on and off at one set of pressures and a second fan on and off at another set of pressures. Keeps the fan use to a minimum. Of course the system would run fine without that.

TR

I use a "differential type" trinary to trigger the fan relay "on" at 250psi & "off" at 200psi of head pressure.

I have a question....How are you guys sending a A/C request to the PCM without the factory control head? Or does the factory "pressure transducer" signal turn the fans on/off based on pressure, speed etc., without a A/C request?

[ls1nova71]

Originally Posted by clinebarger

I have a question....How are you guys sending a A/C request to the PCM without the factory control head? Or does the factory "pressure transducer" signal turn the fans on/off based on pressure, speed etc., without a A/C request?

To send an A/C request to the PCM, you just take the wire that originally went to the compressor clutch, and wire it to the A/C request wire going to the PCM. The catch is, you can only do it on the 2002 and older systems, as the 2003 and up the request is sent via serial data. There has been some talk about being able to change certain files in the tune with Tunercat to be able to use the newer PCM with the older style 12v A/C request, but I haven't looked into it much.

[67C10BUB]

Originally Posted by TR65

Do you guys run electric fans? If so do you have them turn on when you run the AC?

You can also just buy the evaporator unit from Vintageair. That is what I did.

By the way. It is not a switch. It reads the high side pressure. Then in the tune you have tables that allow you to turn one fan on and off at one set of pressures and a second fan on and off at another set of pressures. Keeps the fan use to a minimum. Of course the system would run fine without that.

TR

I am using 2 12" Spal fans on the radiator (I don't have a fan on the condenser). The AC ON switch turns on the compressor (through a binary switch) and also actives a relay that turns both fans on. It seems to work pretty well.

John from Speartech told me that the newer motors (mine is 2008) with the serial AC request will automatically adjust the RPM for the added load. He appears to be right since that is exactly what mine does when I turn on the compressor.

[TR65]

Originally Posted by ls1nova71

To send an A/C request to the PCM, you just take the wire that originally went to the compressor clutch, and wire it to the A/C request wire going to the PCM. The catch is, you can only do it on the 2002 and older systems, as the 2003 and up the request is sent via serial data. There has been some talk about being able to change certain files in the tune with Tunercat to be able to use the newer PCM with the older style 12v A/C request, but I haven't looked into it much.

At least on my 2005 LS2 (E40 ECM) the ECM is quite happy to control the AC system pressure with the fans even though it does not have an AC request. As LS1nova pointed out, I would have to get the AC request onto the serial bus somehow. The only issue is that the ECM can't cut the compressor off in case of a pressure fault.

TR

[mlevario99]

good information, I am trying to install the AC on my truck (is a ford 76), I just bought some fittings and parts to install the AC. I install a 4.8 Vortec from a 04 GMC, but the compressor is form a 2000 Chevy truck. I am keeping the Receiver/Expansion Valve/Evaporator system, can I run it without the trinary switch, I have electric fans on my engine, and the computer turn them on/off. Thanks for your help

[eagleuh1]

Old thread, but worth a try. What condensors is everyone using? I'm running a 2005 5.3 with truck compressor, modified 68 evaporator with white GM orifice tube installed, and accumulator, and the 68 condensor. I have it running with the transduser to control fan on and off, and a low pressure cutout switch in the compessor suction line. Its a little wimpy on the cooling. Thinking about getting a newer condensor or putting a fan on the original condensor.