Let's discuss adding A/C to my 1st gen V8 truck that never had it to begin with..

[Uncle Gump]

I also have to confirm the fitting size on the bottom (outlet) of the evaporator.

This...

Typically... we fill the evap core from the bottom (inlet) with a low temp low pressure liquid... when it boils off to a low pressure low temperature vapor it leaves the evap core from the top (outlet).

Hope that makes sense...

 

[Uncle Gump]

We posted about the same time...

That diagram is exactly what I'm saying.

 

[Bird76Mojo]

So the orifice tube turns a high pressure gas (not high temp because condenser has cooled the refrigerant somewhat) in to a low pressure liquid? In that diagram, it would have to in order to fill the evaporator with a low temp low pressure liquid..

 

[Uncle Gump]

No...

Leaves the compressor as a high pressure high temp vapor... condenses to a high pressure high temp liquid in the condenser... hits the orifice tube high pressure high temp liquid... leaves the orifice as a low pressure low temp liquid... enters evap low pressure low temp liquid... boils in the evap as it absorbs ambient heat and humidity... leaves the evap as a low temp low pressure vapor... the exact pressure and temp as the low pressure low temp liquid that entered ( remember that conversation?)... through the accumulator back to the compressor as the same low pressure low temp vapor.

 

[Bird76Mojo]

Awesome write-up right there! I guess I knew part of it from my A/C class, but it's been a long time, and it seems like I'm confusing myself more and more by building/drawing this system. Especially after looking at an article on installing a system from Vintage Air. It led me astray.

Another quick question:

#1 - Will I install my high side port between the bottom of the condenser and the orifice tube (bottom of evaporator) ?

OR

#2 - Between the compressor and the top of the condenser?


I wouldn't think you'd want it on the liquid line...?

 

[Uncle Gump]

You must have been the guy in the back sleeping through my A/C class... lol

You would usually see a sight glass in the high side liquid line. Pressure tap would be in choice #2.

You build it exactly as shown in the diagram you posted... you won't go wrong buddy.

 

[Bird76Mojo]

It's been several years since I had the class and I've never had to use any of it to make a living. = easily forgotten..

I noticed a couple manufacturers saying to NOT use a sight glass on R134a systems for some reason. I plan to add a high side port in the middle of a hose. That will be the easiest to use since it won't create clearance issues and it will be easy to access. My compressor "block" or manifold already has a high pressure relief valve on the outlet side of the block, so that eliminates one thing I'll have to add.


So I guess I can put the high side port where the "in-line filter" is in the diagram I posted...

I REALLY appreciate all of this help @Uncle Gump !!!! I obviously need it. lol

 

[Uncle Gump]

That location will work... I would favor the condenser side of that line if possible. Depending how close to the compressor that tap ends up... use care putting liquid into the system when static (never charge there with the system dynamic)... it's down hill to the compressor and you don't want to take chances with liquid entering the compressor. I would let the system sit for 5 minutes or so to ensure there is no liquid and the high and low side pressures equalize.

It's not a problem Bird... Glad to help. I might need a little help from you to find me a damn disc to make my cowboy wok... I've looked around and asked a few folks and I've yet to turn one up.

 

[Bird76Mojo]

My buddy just asked if I wanted a disc the other day. He said his father has a bunch of them. They're probably 24" across at minimum. I can try to get ahold of one, but I'm not sure how I'd get it to ya. You're nearly 4 hours away.


As for the location of the high side port, it can be wherever I want it to be. If it's better to have between the bottom of the condenser and the orifice tube (evap bottom) than that's certainly doable.

It's my understanding you don't want to add refrigerant to the high side port anyway. Ever. I've always been told to slowly add it to the low side port on top of the accumulator.

 

[Uncle Gump]

Position #2 is really the best place... If you never liquid charge there... you should never have an issue. It's common to charge there after an evacuation when the system is static... just to dump in the initial charge.

I really haven't exhausted my resources around here for the disc... time has been my biggest issue. I will keep looking as time permits. I know the wife travels down to Champaign once a week and I go too once in awhile to do training for new hires. If push comes to shove... that knocks close to three hours off the travel.

 

[Bird76Mojo]

I was watching a video on a 1994 Ranger having all brand new A/C system components installed and noticed the high side port was within a foot of the compressor and a foot of the condenser in the hose. So that's where I'll put mine. My hose will also be very short for that connection. Probably about the same length as the 94 Ranger's hose is. Although that truck also had some sort of inline filter/muffler in that location with a port for a high pressure switch, which I won't be using since The 87 Ranger and the 92 Thunderbird didn't use a high pressure switch as far as I can tell. Those are my donor vehicles..

94 Ranger hose:

Also posting this here for future use.. My low side port on my accumulator seems to be 7/16" x 20 - which will likely require an adapter (to 13mm) to be hooked up to quick detach gauge sets. I think I'll go with a 16mm high side port splice fitting in the middle of the condenser to compressor hose.

EDIT:

I believe I finally have ALL of my hose ends and fitting figured out now. As well as the R134a adapter for the low side. All of them are added to various carts online, mainly Ebay from one seller with great deals. A few things are far cheaper on RockAuto.

ALL of them were an exercise in patience to find the sizes of the hose ends, thread size and pitch, springlock sizes, etc..

The condenser is supposed to be here tomorrow, so if I can get it in place and still have room for the radiator and mechanical fan, then I'll be going forward with this conversion at full speed.

 

[Uncle Gump]

While WOT is cool... slow and steady will win this race.

Good luck Bird...

 

[Uncle Gump]

Ya know Bird... I was thinking.

The filter in the high side line between the compressor and condenser... is probably a good idea. If the compressor passes any trash... it will find it's way to the orifice... Game over. It may or may not blow most of the refrigerant via your high pressure blow off... depends on how fast the compressor pulls the low side below the low pressure switch threshold.

Your call...

 

[Uncle Gump]

Wait... thinking even harder... you really need this... back to your drawings...

Sorry... but not really

 

[Uncle Gump]

Now I'm going to the junk yard... to buy some junk... and figure out to how bolt my new junk onto my existing junk.