A/C Questions. It's getting hot in Cali!!

[Paso76GMCstepper]

OK Guys here is my question:

I have a 76 K15 4X4. It does not have A/C nor has it ever.

What do I need to keep an eye out for to add a/c to my truck. I would like to use stock a/c if possible. I know Vintage Air is an alternative.

Any info, comments, or anything constructive would be greatly appreciated. The 105 degree days are coming and Im afraid I may pass out in there.

Thanks

[Paso76GMCstepper]

Hello...........

[screwballl]

i am sure there are stock brackets and units but i think it may be better to go with something like a vintage air unless you want to change out the whole heater core, radiator, new belts, etc...

[KShortell]

The aftermarket is going to be the easiest route for you. On our trucks, the A/C and non-A/C trucks evidently had differerent firewall stampings. Companies like Vintage Air have kits designed to work with the non-A/C firewall.

I myself am probably looking at an R-12 to R-134a conversion in the next couple of years. While it checks out and still blows cold, my compressor keeps getting a little louder over time. It groans at idle speeds and has a slight moan at low rpms now. Like they say, "save up"...

Good luck!

[Slonaker]

Tony:

Vintage Air is a relatively expensive alternative. The nice thing about it is that it is a complete kit. You won't end up chasing down a bunch of parts to replace the bad ones in a used setup.

The cheaper alternatibve is to pull the complete A/C setup off another truck. There are differences in the two firewalls, but I am told that the non-A/C firewall can be cut to work with factory A/C.

Kevin:

The low speed groan is not necessarily your compressor going bad. It is a known issue on the '86. GM has a different clutch (I think that is the repair), that fixes it. I have a copy of the service bulletin somewhere if you want a copy.

I have a brand new compressor on mine, and it groans just as bad as the old rebuilt POS one did.

Slonaker

[screwballl]

i was wondering that myself, my 91 burb groans at idle although the burb is loud enough i cant hear it over idle...

[jermasaurus]

When you hear that groan, the high side pressure is usually pretty high. It could be from a restriction (possibly the orifice tube), or not enough air flow through the condenser (which is why it happens at idle). But yeah, I think it is normal too.
I am looking to not only get an electric radiator fan or two, but also but a pusher fan right in front of the condenser to turn on with the compressor clutch through a relay. Not only getting rid of the groan, but blowing at least a few degrees cooler at idle.

[piecesparts]

If you go to an electric cooling fan setup, then look at upgrading the alternator also. YOu will need on the carries more amperage at the idle condition of the truck.

[bringit]

I have a question about AC also. About 8years ago I new a guy with a badass 76 stepside that had some kind of AC unit that bolted under the dash. I think it was from the 70's but not sure, it just looked like a down sized home window unit. It blew ice cold and worked great for him.
Has anyone seen these before and are they avalible still for our trucks? Thats the only one I have ever seen.

[jermasaurus]

Yes, the alternator swap that I am looking to do is using a newer style GM one from the 3 series motors. I have seen one that was installed with little modifications involved mounting it, and a small modification to use the wiring harness for the new one. I am still not sure exactly haow to wire it, but with a diagram it shouldn't be hard.

[KShortell]

Originally Posted by Slonaker

Kevin:

The low speed groan is not necessarily your compressor going bad. It is a known issue on the '86. GM has a different clutch (I think that is the repair), that fixes it. I have a copy of the service bulletin somewhere if you want a copy.

I have a brand new compressor on mine, and it groans just as bad as the old rebuilt POS one did.

Slonaker

I remember that being posted before and someone found out the other pulley has been disconnected or something. I only get a little nervous because this has only been going on the last 3 years or so and has bee getting worse as of late. It's actually getting unnervingly loud. I do wonder if it's glazing on the pulley, though. The pulley seems to have a rubber or synthetic isolator to it.

What makes me concerned is that the truck never used to do this. I've had my truck 11.5 years now, so I have a pretty good idea of all the little quirks and such.

I'd love to get this one solved, though. Summer's almost here and I'm moving home back South!

Thanks for the tip.

[1976K5CHALET]

Okay....
Stock and or Vintage Air are both viable options...
The old school under dash units worked great from
what i understand....and the 79 2wd K5 i dragged home -
rescued from a field has the old school under dash (glovebox)
style of a/c. Which i plan to remove and check out before i cut the body up in little pieces. The stock route requires so fab work on the firewall
after the heater box is removed..which would be the hardest part of the
swap. The gm system works well even when converted to 134a...allthough i have lived in az for 12 years prior to moving to colorado and learned a few tricks to make it work better for us western us CK123 owners.

1) Drill a small hole above the a/c evap box...and tee into the fresh air door vacum line so you can run a vacum operated heater control valve in the heater line...cut off that hot water and its less of a load on the evap...

2) If you have ever looked under the hood of a late model gm truck/burb/ etc...you'll see a neoprene boot around the accumulator...it shields the accumulator that is a storage tank on the suction side of the system....keeping freon in here cold is a good thing....and keeping with the insulation theory Ford used to wrap there suction line from their drier to the compressor also...i recommend doing the same......and going a step farther and insulating the evap box under the hood....just the side that faces the right side of the engine.

3) Since no one currently has a retro fit cross flow aluminum condensor for our trucks as of yet...the trick used to be buying a condensor for a rear air equipt burb as the fin count per square inch was more than the normal C60 air option....these days every manufacturer is down to a one size fits them all approach...so mounting and aux fan on the front of your condensor helps out greatly. You can buy a low psi switch (cycling switch ) pigtail from gm...it has three wires...one is feed to the switch and it has two outlets...one to the compressor and i use the other to trigger a relay for auto operation when the a/c is on....however you can wire it up differently so the fan can be controlled manually. I think the key will be condensor eficiency....so adapting a aluminum cross flow cond is the key to making the system blow ice cubes while sitting threw two stop lights in 100 degree weather...

When a late model 81-2 up i believe R4 compressor starts in with the dreaded death rattle and you let it go till it quits...the repair bill is gonna be larger than you want because it will scatter metal everywhere...and while one can flush out the system with approved flush...its allmost impossable to get all the metal out of the coils....leading to future problems. When choosing a new compressor its either a gm unit or an apco air unit (same co. that remans for gm)....if you go with everco-murray-ready aire- etc (same co) i feel for you....you'll be doing this again at some point.

Not all R4 rattles are the same....on tbi engines...like my wifes 90 the belt tensioner looked fine to me...however when installed the tensioner for the belt has a tit on the back side...the mating hole on the eng bracket is larger than the tit....if you'll loosen op the mounting bolt and push the tension all the way towards the drivers side of the engine bay you might get a surprise and find your noise goes away....

Sorry...i wandered a bit again.

DW

[mkundo]

In my opinon I would stay with the orignal A/C. I like to see these old trucks with all the stock accessiories. You can still fine them here. If I recall there was a coulple for sale recently!