AC Install - 78 K15

[akameriadoc]

Hi All,
I recently purchased a 78 K-15. About two years ago it had its gas engine replaced from a 400 to a 350. When the replacement engine was installed the AC was never hooked back up.

From what I can tell the compressor and accumulator appear to have been removed. Also looks like one of the compressor brackets is missing.





I am looking for some advice on getting the AC working, would love to be able to drive my truck during the summer here in Arizona.

Should replacement parts and recharge of the system be all I need? Any recommended parts? Currently looking at LMC and pick and pulls.

Also does any one have a diagram for the hoses? I found the necessary diagrams for the electrical cabling.

Any info would be greatly appreciated.

[Dead Parrot]

Can't tell from the pics, but do you still have the condensing (hot side) coil in front of the radiator? That might have disappeared during the engine swap.

Might consider a 3rd party compressor like Sanden. Supposed to be better then the pancake GM compressor. Good time to consider options since you are bracket hunting anyway.

[akameriadoc]

Condensing coil is still in place.

I've looked at Sanden and a couple of the other replacement manufactures.

Right now I am thinking about the following from LMC:
32-2700-R Axial Compressor for Chevy GMC 73-84 or
32-2706-Z Radial Compressor for Chevy GMC 78-84

and

32-0422 Accumulator for Chevy GMC 73-80

If i go with the radial compressor I believe the following bracket will work with the front bracket i already have. It looks similar to the one that was in place before.
32-0873 Bracket Rear Adjust Radial Compressor Bracket 305-350 81-87.

[Jimbo0076]

I'd suggest a call or visit to Vintage Air for all the A/C parts. A full A/C kit with every part you need other than maybe a bracket or 2 including all new under dash parts runs right around 13-1400 bucks. Might seem high but I have a 79 truck that has everything A/C wise on it but everything needs replaced. I sell parts for a living and once I added up everything I needed to run a factory system I wasn't but a couple 100 short of new Vintage Air parts. They sell kits for these trucks and they are awesome and work extremely well.

[hatzie]

You can do this with many used parts. I'd lean toward the original Harrison A6 Axial. It's a massive compressor and it moves a lot of refrigerant. It'll work adequately with R134. I've been able to get 45° vent temps on my 76 even with the noticeably smaller Sanden that came on the 1998 6.5L engine. I've done conversions using the A6 on B-Body Buick and Pontiacs that have smaller condensers. They will freeze you right out of the cabin.

70's and early 80's Chevy A & B-Body cars with the smallblocks should have the A6 with the same LH side mounts as the trucks. When you liberate the compressor turn the actual compressor to make sure it's not seized and not making nasty noises. Be sure there's no oil around the nose of the compressor at the base of the clutch indicating leaking seals.

Get new UV leak dye, Polyol Ester Refrigerant Oil in a sealed metal can, R134a seals, R134a barrier hoses, orifice tube, and accumulator-drier.

Refrigerant oils are Aggressively hygroscopic. Polyol Ester refrigerant oil will tolerate contamination with PAG and Mineral oil and is the least aggressively hygroscopic of the three types of refrigerant oils making it ideal for R134a conversions.

The original condenser and evaporator units are HUGE when compared to the volume of the cab. The system will cool quite well with them as long as you take care to flush every drop of the old mineral oil out.

Drain the oil from the compressor, whether it's a new unit or a used one, and measure the amount drained. When I'm ready to close the system I fill the compressor with the same volume of fresh Ester oil as the old stuff I removed. IMPORTANT!! This is not a full oil charge It's just the compressor charge. I install the accumulator and pull a hard vacuum. If the vacuum holds overnight I use an AC oil injector on the Low side port complete the fill to the service manual recommended oil charge (compressor + Injector oil fill should = full oil charge). If you don't pull a hard vacuum pretty quickly the oil in the compressor and desiccant charge in the accumulator will absorb any moisture in the system. You don't want that.

In leiu of pulling a hard vacuum you can sweep the system several times with a dry inert gas like Nitrogen or Inert GMAW/GTAW welding gasses like blends of or straight Argon, Helium, and CO2. This will get the moist air out of the system but it will not get any liquid water. Pulling a hard vacuum is always preferable as it will boil off all the moisture in the system.

As above price it and price the Vintage air system. It has pluses and minuses...
I don't like the 1960's look of the vintage air dash controls. On the plus side the blower, evaporator, and Heater are completely inside the cab making the RH firewall much neater looking.