Adding AC after ls swap

1983 K5 Blazer, originally a 6.2/700r4/208, currently a 350/400/208, soon to be 5.3/4L60E/208. The ac was removed before I got it and I know literally nothing about air conditioning other than my ole lady has got to have it. I know I’m going to need a condenser, evaporator, and the canister beside the evaporator(drier?) compressor, and lines. All the wiring seems to still be there just the lines were cut at the evaporator. I refuse to cut the frame so I suppose I’ll need an adapter or bracketry to mount it elsewhere. What compressor do I need? Can I just get an oem 83 compressor and some adapter to mount it on the 5.3? What wiring do I need from the 5.3 engine harness/ecu? Or can it all be activated by the k5’s harness? I’m trying to do this the most reliable route without spending $3500 on air conditioning.

Sanden with bracket with spacing to match accessories. Use stock controls and run custom hoses.

Assuming sanden is a brand, which model would I need? I’ve never worked with ac so I don’t know a whole lot. Depending how it goes I may add it to my 78 later on for more comfort. I do plan on making this blazer a daily driveable vehicle so comfort and reliability are the only requirements.
Edit: factory replacement parts will work for the condenser, drier, and evaporator? I’ll just have to get special lines and compressor?

Make life easy. since you are basically starting with nothing, spend the $$ and buy a Vintage Air Surefit System. It's new, it's modern (plug & play-no cheesy vacuum lines and sticky cables...etc). It blows cold and it's reliable. One complete system engineered to work together. Don't go down the rabbit holes trying to piece it together trying to save a buck. Report back when finished. BTW-you're exempt from the "LS Swap" suggestion as you have already done the right thing in that regard. Carry on

I’ve debated on that but $2500 for ac isn’t justifiable yet, and with having no knowledge of how any of it works or anything I can’t figure out what all I need. I looked at vintage air and they’ve got every price from 2500 down to 100 for different options included or without. I need literally every piece of the system I’d love to buy a complete kit

I've done 2 LS swaps now, one on an 86 C10 and the other on my 86 C20 Suburban. On the C10 I used a new factory Denso/GM compressor https://a.co/d/aTxtnen part number 15-21177, on the suburban I used the GM Genuine Parts 15-21127 which is a larger capacity compressor from a 2001 Suburban. Now depending on which motor mounts you use, you can use the stock LS compressors mentioned above with only a little trimming of the front frame rail.

These motor mounts are what I used https://tejassteelworks.com/product/squarebody-ls-motor-mounts/ , they're cheap and the engine seriously falls into place with them.
Tejas SteelWorks has a pretty good guide for LS swapping a squarebody. https://tejassteelworks.com/wp-content/uploads/LS-Swap-Guide-73_87.pdf

The other parts you should be able to find from someone parting out these trucks local to you. You will want to buy a new evaporator, condenser, acumulator(drier), and heater core while you're at it. As far as the custom AC lines I followed this guys guide for which fittings etc I needed from coldhose.com, coldhose can make the lines and has the Denso/GM style compressor fitting adapters. Let me know if the link doesn't work and I'll try to copy and past the fitting part numbers and line orientation needed.

Let me know if there is anything else I can help with. I have a youtube channel where I have attempted to document how I have went about doing these swaps. Here is one that shows the motor mounts and frame mods for the compressor.

consti2tion said:

I've done 2 LS swaps now, one on an 86 C10 and the other on my 86 C20 Suburban. On the C10 I used a new factory Denso/GM compressor https://a.co/d/aTxtnen part number 15-21177, on the suburban I used the GM Genuine Parts 15-21127 which is a larger capacity compressor from a 2001 Suburban. Now depending on which motor mounts you use, you can use the stock LS compressors mentioned above with only a little trimming of the front frame rail.

These motor mounts are what I used https://tejassteelworks.com/product/squarebody-ls-motor-mounts/ , they're cheap and the engine seriously falls into place with them.
Tejas SteelWorks has a pretty good guide for LS swapping a squarebody. https://tejassteelworks.com/wp-content/uploads/LS-Swap-Guide-73_87.pdf

The other parts you should be able to find from someone parting out these trucks local to you. You will want to buy a new evaporator, condenser, acumulator(drier), and heater core while you're at it. As far as the custom AC lines I followed this guys guide for which fittings etc I needed from coldhose.com, coldhose can make the lines and has the Denso/GM style compressor fitting adapters. Let me know if the link doesn't work and I'll try to copy and past the fitting part numbers and line orientation needed.

1985 C10 LS Swap Partslist

docs.google.com

Let me know if there is anything else I can help with. I have a youtube channel where I have attempted to document how I have went about doing these swaps. Here is one that shows the motor mounts and frame mods for the compressor.

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I appreciate your build list, that was very helpful, especially the AC hose list! What offset did you put the suction port on the dryer hose when you sent it back?

square85c10 said:

I appreciate your build list, that was very helpful, especially the AC hose list! What offset did you put the suction port on the dryer hose when you sent it back?

Click to expand...

I wish I could take credit for the list but another gentleman put that together, I don't know what he ended up putting it at. I took mine to Napa to get them to crimp the fittings on the suction line so I could clock them however I needed to. Not sure if you have one local to you but they didn't charge me to crimp fittings. I have since bought an AC line crimp tool from amazon, knock off of the Mastercool. Hindsight I should have spent the money on the Mastercool but the one I bought works well enough.

My 1986 C20 Suburban has a replacement 350, what is the best (and most economical) method of adding A/C back?

After a very long time, and replacing the LS the blazer finally runs. So I’m back to ac, can I use a full system from a 88-91 k5, burb etc? And a bracket to move compressor to the top and have a factory system? After reading alot about vintage air it just doesn’t seem like the cost is worth the reward.

I can tell you that a vintage air will not keep the larger space of a Blazer cold. It will make it less miserable but won’t chill you.

Yes you can use the donor system.
Get a sanden 508 compressor and a bracket from ict billet


As motioned previously, buy the bracket that corresponds to your engine spacing/distance.

Good advice above, I'll recap here:
You can get a bracket to move the squarebody AC compressor to the LS, but I think most, myself included, would say getting rid of the R4 would be a smart move. They don't seem to last, and they don't crank as cold as the right modern compressor will. And the cost to buy that vs another option is probably the same. Pass.

The factory LS compressors are low mount, so if you used Tejas motor mounts, Consti2tion's recommendation is spot on. Use the factory replacement for a Tahoe or a Suburban with rear air if possible, but the regular truck compressor won't be terrible. It's a little smaller, I think, and does almost as much capacity for a Blazer. But these use a 4 rib belt, and can't be relocated to the top of the engine without changing the spacing and pulley significantly, and I don't think anyone has a kit to do so. So either Tejas mounts or cutting the frame on that one.

If you used a different mount package and don't want to cut/trim the frame, Zelph's recommendation should work better. Use the K5 parts as much as possible. An upgraded Condenser with the parallel flow is going to make you much happier on a R134a system (see the spreadsheet Consti2tion posted for a part number and link for everything but the compressor and hose parts). You will need a new filter/drier no matter what. Existing lines and evap core is up to you, but I'd recommend starting fresh on it all.

Coldhose or a local shop will get the hoses and fittings taken care of for either new compressor option. Any of those options can use the K5's clutch signal and cycling switch that goes into the silver can on the firewall, and your dash controls shouldn't need anything as long as they worked with the factory AC before.

Wanting to do the same and replace old condensors and such, I'm looking at around $1,000. This includes a high mount bracket which are way over priced.

FYI, years back when ICT had the brackets for the old compressor for ~$300 and also sell the new high mount bracket for a new sanden compressor for $120.....that racket caught my eye pretty quick and pissed me off. Hence no A/C yet. Forget those prices now. At that time, they wanted you to buy a compressor from them. $h|t pi$sed me off so I didn't get A/C. Was a damned if you do, damned if you don't when it came to what compressor you wanted to use.

[edit] sorry for multiple edits.....just p|s$'s me off and was so obvious.

was $115

https://www.amazon.com/Sanden-Truck-Conditioner-Compressor-Bracket/dp/B078XPGY8Y/ref=cm_cr_arp_d_product_top?ie=UTF8

was $300

https://www.ictbillet.com/ls-truck-a-c-compressor-relocation-bracket-kit-lm7-l92-l96-lsx-4-8l-5-3l-6-0l.html

point being....it's a bracket they cut, why was one more than the other.

After 3 failed R4 type compressors, I went with the Sanden 508 and top mount bracket kit from Holley. It wasn’t cheap but it was the easiest option. With the help of this great board, figured out that my condenser was the weak link and upgraded to a parallel flow and it was money. It was suggested to run the bigger 7 series Sanden, but with the new condenser the 508 is working great to run front and rear air on the Suburban. All the other components on mine are factory, but running 134a. Those R4s suck a bunch of power too, noticeable on the butt dyno for sure.