Suburban A/C fix + Vintage Air?

[ShortHaul]

Just read this entire epic endeavor. Props to you for sticking with it. I’m soon to be an owner of a ‘75 Burb with rear ac (not currently working) so I’m preparing for the inevitable. Seeing that you’re local to me, I figured I’d check in here. Aside from the AC, do you have any pics or a build thread for your Burb? Sounds pretty badass!

[swissarmychainsaw]

Originally Posted by ShortHaul

Just read this entire epic endeavor. Props to you for sticking with it. I’m soon to be an owner of a ‘75 Burb with rear ac (not currently working) so I’m preparing for the inevitable. Seeing that you’re local to me, I figured I’d check in here. Aside from the AC, do you have any pics or a build thread for your Burb? Sounds pretty badass!

I have a couple suburbans actually ... sigh...LOL
Here are pics of this one: https://swissarmychainsaw.smugmug.co...Owned/Suburban

[ShortHaul]

Originally Posted by swissarmychainsaw

I have a couple suburbans actually ... sigh...LOL
Here are pics of this one: https://swissarmychainsaw.smugmug.co...Owned/Suburban

Niiiiice! That thing’s cool!

[swissarmychainsaw]

My parts are coming in about a week and there are some open items

1. Need a Crimping tool [edit: AC lines ]

2. Vacuum Pump and gauges

3. How much Refrigerant is needed in this system?

4. Need to be able to trigger fan: off/low/high on rear AC unit

5. Need to verify that my rig can trigger the AC to come on (not sure how that even works)

Any recommendations on any of these?

[hatzie]

Electrical or AC lines?
For AC lines the Mastercool 71550.
For electrical terminals Delphi 12085270 and Delphi 12085271

[jjzepplin]

Subbed in this one. I don't have a Burb but I am sure interested,

[swissarmychainsaw]

I bought some stuff:
Vacuum pump and manifold gauges.
*Why I bought this one: Price, reviews and pretty blue case!*

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Orifice Tube tool:
*Why I bought?*
Orifice tube and expansion valve (install explained)
https://www.youtube.com/watch?v=MxHBD73VKfQ


https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

AC Crimper Tool
*Why I bought this one: I was going to get the non- hydraulic (more reliable version) but I realized that you can't
use that type easily when the hoses are on the car. So I went with this one (ratings, and number of dies in the kit).*

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Thermometer(s)

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Refrigerant Tap:
Why? One of the reviews I read on the Manifold said this was the one that worked for him.


https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

I have a trip planned for *June 19th*, so that is my "get er done" drop dead date.

So I'll keep posting as this progresses. Expecting some parts soon...

[jjzepplin]

Oh man! You are going to be an AC king! I did a whole system in a Toyota (wife's car) compressor, evaporator, condenser, etc. It was so cold that my wife wanted a setting lower than low. I told her that setting was "OFF".

[hatzie]

Let us know how the Mastercool Hydracrimp knockoff works.

[swissarmychainsaw]

It has begun ...

[jjzepplin]

I see some goodies! Warm fuzzies yet? I just got my Sanden in the mail. I am about to get going on mine. I also bought the Mastercool but I got the Manual one. I have two AC's to do. Good luck!

[swissarmychainsaw]

I was not expecting this until Monday, and I made some weekend commitments that will prevent me from tearing into this straight away.
Stay tuned though!

Oil Capacity & Refrigerant


I emailed the AC supplier Mike O. from Classic Auto Air in FLA, and he called me back.
So far this guy has been a huge help on this project.
It's pretty custom and not many suppliers will help with piecing a system together. I'm very grateful.

Here are notes from my call with him.

Oil
Using the chart above the dual air system uses 3 ounces more than a single system.
He said that the compressor comes with all of the oil needed for it to run properly; however, since it's a dual system adding an extra 3 ounces of oil is probably a smart move.
The explanation for this was the evaporator in the rear does not travel any oil and in front it is a plate and fin design which can trap some oil.
The accumulator collects some oil in meters it somewhat.
Conclusion: add 3 ounces of oil to this system with a new compressor that is already full of all oil.

Refrigerant Charge
Typically when converting to 134a you use 70 to 80% of the original charge amount. (as a reference)
However in practical application he said to add 2 pounds into the system and run front and rear on high full blast for 30 to 45 minutes and measure the temperature, front and rear.

After seeing what the lowest temp. you can achieve is, add 1 ounce of refrigerant and wait 5 to 10 minutes to see if your temperature drops more.
Repeat this process until the temperature no longer drops. And you're done.
Record amount of refrigerant for future servicing (because no one will know how much to put in)

Note that this uses a parallel flow vs. stock will impact how much refrigerant to use.

Other things
When charging and testing the system just let it idle, driving it is not recommended.

Lube o-rings with Oil before install (comes with oil)

Attache fittings by Tighten them by hand and then with two wrenches tighten them 1/2 to 3/4 turn more. Don't over tighten, it will pooch your o-rings.

[swissarmychainsaw]

This thing is huge...



So I'm officially one beer into this project and realize I need more fittings.

[swissarmychainsaw]

There are several lines I got from the parts truck I wanted to use (these are hard/rubber lines).
Here is a video on how to "repair" AC lines, which means you replace the rubber part with new rubber and braze on new fittings.

This seems like the way to go if you have the parts.



https://www.youtube.com/watch?v=GIyY9FJXiis

[swissarmychainsaw]

So, I'm trying to move from an intimidating pile of parts to something that resembles an air conditioning system.

Thankfully I had my 11 year old help me sort some things out.

The main thing was to lay everything out and see what connects to what and if we had all the connections we needed.

When it's all in a pile it does not make much sense, so "test fitting" everything was a good use of time.



This will be the hose routing for the rear unit.



And here is my high tech drawing of how the components go together.
Red: -8AN fittings / hose
Blue: -10AN fittings/ 13/32 hose
Green: -6AN
Both service ports will be at the compressor fittings.

[swissarmychainsaw]

BTW if anyone has a truck that has AC, can you tell me what color wire goes to the compressor, and then where it goes?

[hatzie]

Compressor clutch is green.
It runs from the HVAC panel through the LPCO switch and then to the compressor.

[swissarmychainsaw]

Originally Posted by hatzie

Compressor clutch is green.
It runs from the HVAC panel through the LPCO switch and then to the compressor.

Thanks! I'll have more questions on this today. I'm thinking about how to test this. If I turn the AC on in the cab should power then be sent to the LPCO?
Is a simple test light enough to test if that is working?

I got the compressor bracket painted up yesterday.




Finally a good reason to try this stuff out: Steel-It

[jjzepplin]

That looks like some wicked paint. Where do you get that?

[swissarmychainsaw]

Originally Posted by jjzepplin

That lloks like some wicked paint. Where do you get that?

It is wicked paint. The Baja racers use it on roll cages and stuff, as you can weld through it. The youtuber "Merricks Garage" used it and raved about it. I like the look and toughness. Though I find that dude annoying.

Amazon! And YES it's shockingly expensive.
I bought some a while back just to try it, and have not had a good occasion until now.
There are also some good youtube reviews of this stuff (rust resistance)

https://www.amazon.com/Steel-it-Poly.../dp/B06Y49G41W

[swissarmychainsaw]

Two things I need sorted out that I'll take opinions on.

1. Need to trigger the electric fan(s) when the compressor kicks on.
(This is a carbed LS motor with MSD box - how the fan gets triggered)
How should I do that?
Edit: The answer is a Trinary Switch
https://youtu.be/l604JCZx_ow

2. The Rear blower needs a switch and power run to it. Thoughts?
I have heard that with rear units, you want to run the fan anytime the AC is on to prevent icing. Can I trigger it from the front fan unit? Via a relay maybe?
that way when I put the fan on, and the AC is on, the rear unit also gets power?

Just making my to-do list, and the above are still in the "idea" phase.

It's going to be hot today, but the show must go on!

[swissarmychainsaw]

I'm trying to install the condenser. The "kit" is a bit of a joke, so I'll have to fab up some kind of bracket.
All the stock mounting stuff is gone.

Two questions:

1. Does the lager port of the Condenser (8AN) have to go on top, or does it matter?
Edit for future generations: Large port on top!

2. Which side of the radiator?
Does it matter if it goes on the grill side or the fan side of the Radiator?
Edit for future generations: It seems that ALL of them are on the fresh air side!

Stock one goes on the grill side, but the hoses do a better job of passing through the core support than my big rubber lines will. It might be easier to just put it on the fan side.
I never considered that until I just saw a pic of someone doing that on the internet!

[swissarmychainsaw]

Next up is the Condenser. The trans cooler is in the way, and let's just say the mount is "home made" (plumbers tape anyone?)





Test fitting the 8AN hose.
If I had more time I'd just do hard lines from the condenser and through the firewall. Vintage air make some "U-Bend-Em" that might work for this.



Here is the mount provide by "Classic Auto Air", it looks pretty good with the Steel-It paint. At first I thought the mount was very plain looking.



And of course, once installed you hardly see it.



Compressor install was a piece of cake, really. The kit even included a new belt which is one less thing to have to measure, and track down.

Next up is sorting out the wiring... and hoses.



Found this on 73-87chevytrucks.com (they have a forum for AC it seems)

[hatzie]

You can find the whole GM wiring diagram book for your truck in my manuals post in my signature.
I gave Chris copies of my scans for that board.

[swissarmychainsaw]

Originally Posted by hatzie

You can find the whole GM wiring diagram book for your truck in my manuals post in my signature.
I gave Chris copies of my scans for that board.

In my opinion you have earned your way into heaven for doing that! Thank You!