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Looking for ANY help/ideas on how to convert from new LS A/C system to an older 72 era system. Specifically I would like to use my new LS A/C compressor and mate it to my older A/C condenser units etc. The vehicle is a 72 Chevrolet and the motor I've got in there is a LS6. Too far down the trail to change much and hopefully I can hear from someone who has already done this and to what degree of success. Basically I need to figure out the hose arrangement and whether or not the new style compressor will function properly with an older evaporator and condenser unit.
Couple of tips:
1. Make sure you use a fixed displacement compressor. These are compatible with old AC parts (evaporator). I used truck compressor Denso unit 10S20F successfully with vintage air.
2. I bought a master cool manual crimping tool for about $150 from Amazon and then the bulk hoses and ferrules from http://nostalgicac.com
3. I did have to buy an adapter from the compressor for the -6 and -8 threaded fittings to the compressor to match up with the old style hoses. They are available from ebay or other. Here's an example: http://www.ebay.com/itm/LS-Swap-AC-C...-/281495887879
4. Make sure to get a new receiver / dryer.
5. I bought from Harbor Freight their manifold gauges and evacuator vacuum pump. I bet they are on sale this time of year
DW, I truly appreciate your response! When you say fixed displacement compressor, at present time I do not know what type I have but it came out of a 2000ish Chevrolet truck.
I will definitely look into the links you sent and go from there.
A few more comments:
Pretty sure yours would be fixed displacement (vs. variable). I don't think those (variable) became popular until later.
Take a look at the model # info on it and then google search - use terms fixed displacement and some link will take you manufacturer's info on the compressor.
The F in 10S20F stands for Fixed for Denso compressors.
Mastercool is all one word.
You will also need hose ends from nostalgic. Another option is getting those parts, mock everything up and then index them with marks (so the ends are clocked properly) and then bring them to an AC shop for Swaging. I had a quote from a shop to just build two lines for $300. For less, I ended up with the swaging tool and the parts I needed to assemble. It doesn't take long to assemble the hoses.
[QUOTE=DW SD;18533810]Couple of tips:
1. Make sure you use a fixed displacement compressor. These are compatible with old AC parts (evaporator). I used truck compressor Denso unit 10S20F successfully with vintage air.
Ok here is my compressor, no identifying marks on it anywhere of course. So do you happen to recognize which model this could be?
I have used a F-Body Compressor with my swap with 71 Stock AC. I had my old and F-Body AC hoses made up using the old ends and was able to connect everything up like it was stock AC for the 71 Chevelle.
I just connected the Green wire to the compressor connector with the other end to ground. So it operates from the old controls.
As noted by everyone, It works better with a fixed displacement compressor. The F-Body on is a Variable one. So it has trouble keeping up when I am in slow bumper to bumper traffic. Otherwise it works well.
There are some write up on converting the Variable one to locking it up to full 100%.
Ok here is my compressor, no identifying marks on it anywhere of course. So do you happen to recognize which model this could be?
Judging by the high pressure sensor in the back of it, that is about a 200-2002 truck compressor, or a 2002-2007 van compressor. They are fixed displacement. You say you have an LS6? That's a Corvette engine, and the accessory drive is different than a truck, so if that's what you actually have, it won't fit your engine. If you in fact have a truck engine, then you should be good to go. A pic of the engine will help if you are unsure what you have, Also, what kind of '72 Chevy is this in??
Judging by the high pressure sensor in the back of it, that is about a 200-2002 truck compressor, or a 2002-2007 van compressor. They are fixed displacement. You say you have an LS6? That's a Corvette engine, and the accessory drive is different than a truck, so if that's what you actually have, it won't fit your engine. If you in fact have a truck engine, then you should be good to go. A pic of the engine will help if you are unsure what you have, Also, what kind of '72 Chevy is this in??
To be honest it's an L33, my mind was elsewhere when I said LS6...I am putting this in a 1972 Blazer. I popped a Z06 cam in it, rebuilt the 243 heads with new springs, seals, lapping, etc. New rings, oil pump, gaskets, all the necessaries. I've heard I will lose my bottom end but I will not be climbing anything with this truck and will be doing more highway cruising than anything else. The AC compressor came from a donor motor which is now in my 2007 Chevy truck (where I got the L33 from due to a rattling lifter).
Ahh, gotcha. So your Blazer has factory air and you are wanting to run it with the 5.3's compressor, correct? I did the same thing on my '71 SWB, and it works awesome! I did change the evaporator to a newer one that uses an orifice tube rather than the somewhat problematic POA valve and expansion valve. It's a pretty straight forward swap. I had barb fittings TIG'd onto the fittings that go on the compressor, so new hoses could be crimped on. There are pics in my build thread of my rusty 71 in my sig if you want to see exactly what I'm talking about.
I'm also currently building a '72 Blazer, 6.0/4l80e. What part of Missouri are you in?
Pretty easy to do, like everyone says. A good upgrade is a parallel row condenser. I do recommend getting the biggest you can fit. Be careful on the amount of refrigerant you try to charge with, and don't overfill the system. The POA eliminator is also a really good idea. I bought my custom hoses and adapters from www.coldhose.com as well. Well made, quick and competitive.
Ahh, gotcha. So your Blazer has factory air and you are wanting to run it with the 5.3's compressor, correct? I did the same thing on my '71 SWB, and it works awesome! I did change the evaporator to a newer one that uses an orifice tube rather than the somewhat problematic POA valve and expansion valve. It's a pretty straight forward swap. I had barb fittings TIG'd onto the fittings that go on the compressor, so new hoses could be crimped on. There are pics in my build thread of my rusty 71 in my sig if you want to see exactly what I'm talking about.
I'm also currently building a '72 Blazer, 6.0/4l80e. What part of Missouri are you in?
LS, I live in Southwest MO, about 45 min from Joplin. You?
thanks again for the great information! I will hop on your build thread and check out your approach.
I found this one on Ebay for about $80.00. It is the passenger side which is the only side I am having issues with. What are your thoughts on using just the one from the SS and keeping my other one from the truck? It saves me some $$ and hassle of trying to find the drivers side unit.
Also are the flanges the same or will I need to source/fabricate a new flange?
I also had a quick one about the tach. The white tach wire that has been set aside in my wire loom, will it drive my factory tach in the 72? I doubt that it will but I had to ask. I assume my factory tach is 12V driven and the one from the ECM is less than a volt or two maybe? Advice?
I found this one on Ebay for about $80.00. It is the passenger side which is the only side I am having issues with. What are your thoughts on using just the one from the SS and keeping my other one from the truck? It saves me some $$ and hassle of trying to find the drivers side unit.
Also are the flanges the same or will I need to source/fabricate a new flange?
I assume that's a Trailblazer SS manifold? They work great on a 2wd, and since a 4wd the engine is further back, where the frame gets wider, then it should work even better. I wouldn't see a problem using your truck one on the driver's side as long as it fits. The flange where the exhaust pipe hooks to them are the same for the TBSS and trucks, so you could use your original truck one.
I also had a quick one about the tach. The white tach wire that has been set aside in my wire loom, will it drive my factory tach in the 72? I doubt that it will but I had to ask. I assume my factory tach is 12V driven and the one from the ECM is less than a volt or two maybe? Advice?
Ken
I've put factory tachs in two of my trucks and they work fine. You will most likely need a 'pull up resistor' to strengthen the signal to the tach to make it work, but it's pretty simple, it's just a 1000ohm 1/4 watt resistor that you can get from Radio Shack for a buck or so, and put it between the ignition power terminal and the signal terminal on the back of the tach. http://lt1swap.com/lsx_tach.htm
I have to say you are saving me a TON of heartache, time and money. For that I am truly grateful. If I ever get up to Independence, I would enjoy coming by and visiting with you and checking out your latest projects. Likewise if you come down toward Jane, MO. Oh btw, I get over to classic parts quite often so if you ever need me to check on anything or grab something, just let me know.
I have to say you are saving me a TON of heartache, time and money. For that I am truly grateful. If I ever get up to Independence, I would enjoy coming by and visiting with you and checking out your latest projects. Likewise if you come down toward Jane, MO. Oh btw, I get over to classic parts quite often so if you ever need me to check on anything or grab something, just let me know.
Ken
No problem. I've done so many of these trucks, I think I can do them in my sleep. If you're ever up this way just let me know. Also, what classic parts are you referring to? The only one I know is in Riverside, which is up here by me.
No problem. I've done so many of these trucks, I think I can do them in my sleep. If you're ever up this way just let me know. Also, what classic parts are you referring to? The only one I know is in Riverside, which is up here by me.
There is a pace here in Bentonville called H&H Classic parts. I assumed you were referring to them. They have a large selection of classic chevy stuff.
11-18-2014, 01:55 PM
A/C new to old conversion 
If you're ever up this way just let me know. Also, what classic parts are you referring to? The only one I know is in Riverside, which is up here by me.