Adding factory AC to my non-AC 1970 truck

[demian5]

I scored a fairly complete working system (minus condensor, compressor brackets, hoses, and controls). But boxes, cables, evaporator, heater core, ducts, even a good AC glovebox.

I can get the parts missing locally unless someone has some they want to part with.

Bonus is my truck already has an AC dash and I can do all the work myself.

Any gurus that have done this have any advice? I figured ill pressurize the EVAP core and check for leaks and replace the heater core just to prevent needing to later, along with a new receiver drier.

How do I need to modify my firewall?

Are there upgrades to the POA valve or oriface tube that I should do to bring it up to modern technology?

I have R-134 at my disposal but freeze 12 I can get too (and have gauges for both).

Anything else?

[mrein3]

I put AC on my truck a few years ago. Scroll down to post #8 in:
http://67-72chevytrucks.com/vboard/s...d.php?t=478564
for details.

The link in that older thread to adjust your POA broke since I posted it. Sorry about that.

I'm sure the parts prices I quoted are no longer any good. Everything has gone up since then. Except my salary.

[demian5]

Originally Posted by mrein3

I put AC on my truck a few years ago. Scroll down to post #8 in:
http://67-72chevytrucks.com/vboard/s...d.php?t=478564
for details.

The link in that older thread to adjust your POA broke since I posted it. Sorry about that.

I'm sure the parts prices I quoted are no longer any good. Everything has gone up since then. Except my salary.

Right one. Can you tell me more about the flapper? Looks like it is not a simple bolt-on...

[mrein3]

The flapper is in the cowl, in front of the windshield on the passenger side.

In a non-AC cab there is a dimple in the sheet metal that needs to be drilled out. I bought one of those super long drill bits as the dimple is pointed out towards the engine. I drilled the hole to factory specs from the assembly manual. Obviously the glove box is out to perform the task.

I believe the hole is all you need to "add". Then it hooks up to vacuum with a T in the vacuum running other AC components.

The flapper is part of the outside air/no outside air control system.

[randy500]

The shape and size of the openings in the firewall are different behind the a/c outside box (larger) so the firewall can be cut to a/c size. The holes for the boxes are mostly different locations, I think if you mount the outside box first you can locate the remainder inside and outside holes from the outside box.
The assembly manual has hole locations and sizes for that flapper door and the wiring/vacuume hole, maybe some more info too.
A/c wiring is just an add on to regular harness.

[demian5]

Originally Posted by randy500

The assembly manual...

Is there a PDF version floating around yet?

[F.A.A.benny]

If going with 134a you should recalibrate the poa valve

[demian5]

Originally Posted by mrein3

The flapper is in the cowl, in front of the windshield on the passenger side.

I totally understand how it works now. That may be something I didn't get with the kit.

[demian5]

Here is what i'm getting.

[F.A.A.benny]

Be sure to check that distribution duct that bolts directly to the heater box. Often the blend door is broken. That duct is over $100 new

[demian5]

Originally Posted by F.A.A.benny

Be sure to check that distribution duct that bolts directly to the heater box. Often the blend door is broken. That duct is over $100 new

Will do. What does it look like i am missing?

[Boog]

Difference in firewall holes. a/c and non a/c.

[demian5]

Originally Posted by Boog

Difference in firewall holes. a/c and non a/c.

That is great information.

What benefits (and how) can I convert over to a later style oriface tube and get rid of the POA and the associated stuff to make it more reliable?

Is it worth it?

[F.A.A.benny]

Originally Posted by demian5

That is great information.

What benefits (and how) can I convert over to a later style oriface tube and get rid of the POA and the associated stuff to make it more reliable?

Is it worth it?

You will have to change the evaporator to run an accumulator/orifice tube setup. It could be something like this.https://www.classicindustries.com/product/ap7228.html

[mrein3]

Originally Posted by Boog

Difference in firewall holes. a/c and non a/c.

Originally Posted by demian5

That is great information.

What benefits (and how) can I convert over to a later style oriface tube and get rid of the POA and the associated stuff to make it more reliable?

Is it worth it?

First on the a/c and non a/c firewalls. The picture isn't lined up perfectly. The existing heater hose hole in the non A/C firewall is the same on the AC firewall. There is a dimple for the other hole. I drilled that dimple then used a greenlee hole punch to make a nice, neat hole. If you look at my post I linked I cut and welded the big holes to mimic the factory firewall. I used the AC heater box to make a template that I transferred to the truck.

Regarding the POA. It has nothing to do with reliability. It is just a different system. If you have a POA system, I'd use it. The factory ACs on my two Chevelles have been used reliably since 1971 and 1972. The '71 still has the factory receiver/dryer. The 72 I did some service on in 1989 at which time I opened the system to replace something - I don't even remember what any more - and replaced that receiver/dryer at that time. ANY system like this vintage, when you open it to the atmosphere, should get a new receiver dryer.

The truck I converted is using a factory compressor off of a 1971 Monte Carlo. That system has been working since 2011. It has a slight leak. I replaced every o-ring in the system but didn't touch the schrader valve. Guess where it leaks?

[demian5]

Originally Posted by F.A.A.benny

You will have to change the evaporator to run an accumulator/orifice tube setup. It could be something like this.https://www.classicindustries.com/product/ap7228.html

I like this idea. I could go with a later model compressor and condensor too. Should I add a pusher fan that runs when the ac is on?