Suburban A/C fix + Vintage Air?

[swissarmychainsaw]

Originally Posted by hatzie

...Snip...

When I convert over to the Sanden style compressor I run the ground through the High Pressure Cutout Switch and leave the LPCO in the hot as originally wired. You can run the HPCO in series with the LPCO but it's easier to put it in the ground side.

Thanks for this.
I just reached out to the supplier of my parts:

The modern compressor do not have any switches in them, so it is recommended to install one. Here is a link to a very easy to install switch kit.

https://www.originalair.com/ac-high-...tch-kit-o-ring

In your situation, it would need to be attached to the lower fitting of the condenser (#6) and then attach the hose directly to that.

Just ordered this, but I don't think it will get here in time for my vacation plans!

[hatzie]

Originally Posted by swissarmychainsaw

Thanks for this.
I just reached out to the supplier of my parts:

The modern compressor do not have any switches in them, so it is recommended to install one. Here is a link to a very easy to install switch kit.

https://www.originalair.com/ac-high-...tch-kit-o-ring

In your situation, it would need to be attached to the lower fitting of the condenser (#6) and then attach the hose directly to that.

Just ordered this, but I don't think it will get here in time for my vacation plans!

You could get a crimp in pressure switch fitting and install in the hose right off the compressor head.

The compressor head fittings, be it a Sanden or one of the Harrison units, can be acquired with an HPCO threaded switch fitting... and even both LPCO & HPCO threaded switch fittings.

[swissarmychainsaw]

Originally Posted by hatzie

You could get a crimp in pressure switch fitting and install in the hose right off the compressor head.

The compressor head fittings, be it a Sanden or one of the Harrison units, can be acquired with an HPCO threaded switch fitting... and even both LPCO & HPCO threaded switch fittings.

Like this?
https://www.summitracing.com/parts/vta-24678-vus

So is the Low pressure switch a "binary" and the high pressure "trinary"?

Edit: Found this on "trinary switch" -- If you need to trigger an electric fan, use one!
https://www.youtube.com/watch?v=l604JCZx_ow

[swissarmychainsaw]

Ok, now I'm scratching my head.

So I believe this to be a low pressure switch, can anyone confirm that?

Can I also use that unused "port" (with the black cap) for a high pressure trinary switch?

[hatzie]

That is indeed the LPCO switch.
The black capped fitting is the low pressure manifold gauge service connection.

The HPCO has to be in the high pressure side of the system. Usually right off the compressor in the high side line.

[swissarmychainsaw]

Holy Cow, I ordered a Trinary switch from Summit Racing YESTERDAY and it's in the mailbox already. Less than 24 hours. Crazy.



Here we go!

Brackets for the condenser. I took the "install kit" cut it and bent it to use existing hols in the core support.




Final of the Condenser bracket install. Getting this all in there was the hardest part so far.

[swissarmychainsaw]

The moment of truth:



The first crimp!



Now like 45 to go!



Mocking up:



Routing the hoses is harder than I thought it would be.

I don't want it to look like a cluster. Every combination looks weird!

[swissarmychainsaw]

Running the lines and mocking things up before "the final crimpdown!"

[swissarmychainsaw]

This gives me feelings of optimism:



Drain Hole from "kustom drain holes express"



yes, buy some extra length hose, just in case!



Aaaaand Here is the final mock up before all the crimpin' goes down.
Might not win a trophy, but if she blows cold, well, winning!

It looks like those hoses touch the belt in this pic, but there is plenty of room.

[swissarmychainsaw]

Carry on my wayward son...












Ok so all crimped up and read to rock and roll.

Now for the bad news:
Never was able to pull more vacuum than this.



And after I shut it off, I lose vacuum.






So I have a leak in all my glorious crimps and connections.

What next?

[swissarmychainsaw]

Seems the smart thing to do is to put some compressed air into the system and spray some soapy water the connections.

Here is a video that shows the procedure I used
https://www.youtube.com/watch?v=J6DSpx1V3Ms

Basically you put a rubber tipped air gun where the yellow vacuum pump hose goes, and pressurize the system, then with a spray bottle of soap and water get to squirting on your joints.
The great thing about air leaks is that you can *hear them!

So I found the leak!



This puppy was hissing air.

Now, no one in their right mind would put a junk yard Low Pressure Cut Off switch on their brand spanking new AC system...would they???

Next up, we put it back on the vacuum pump and see if it holds! Fingers crossed.

[jjzepplin]

Hang in there! It's probably something simple. Check all your fittings for O rings and damaged O rings as well as switches.

[hatzie]

Make sure the Schraeder valve on the service port that's on the side of the accumulator isn't leaking.

[jjzepplin]

Yeehaw!

[SCOTI]

Persistence!

[swissarmychainsaw]

Thanks for the encouragement fellas!

This seems really simple when I draw up this pic, but it took me a while to get there.
Thanks to @hatzie for suggesting this wiring strategy of using a relay for the compressor!

Not shown is the relay and switch for the rear AC Blower.



This means the wiring is now hooked up, and I can potentially run the system today.
Is today THE DAY?

I'm sure there are about 30 things that need buttoning up, but I'm going for it!

Here is some wiring for your enjoyment, not many folks appreciate a good crimp!



A little wire loom makes those wires look a lot better:



This is when you know you should step away from the heat gun.

[swissarmychainsaw]

I need to add about 3 oz of PAG oil to this system.

I arrived at that number by looking at the manual and talking to the sales/tech, the original system (with dual AC!) had 3 oz more then the since evap system.

So assuming the compressor has enough oil in it for a single AC system, we then will add 3 oz for a dual.

How should I add the oil?

I need to pull a vacuum on it anyway, so it's open, now.

I'm seriously considering opening one of the rear lines and just pouring 3 oz in.
Considering the rear lines are 15 feet long, I don't think it should be a problem.

[swissarmychainsaw]

Wiring done enough to run the system



Only add to the high pressure (discharge) side or your compressor will suck in liquid oil and the sun will stop spinning in the sky!



Make sure you have a good assistant!



Right now, we are pulling a vacuum and double checking Last Time for leaks!

[jjzepplin]

FANcy!

[jjzepplin]

Oh man, I can barely breath... My virtual finger are crossed for you.

[hatzie]

I would recommend drawing up a schematic of the wiring so when you come back to it in 3 years you can figure out what you did...
As an occasional buyer... It's a selling point to have a wiring diagram for any hot rod.
Even some custom shops will refuse to work on electrically modified vehicles without documentation because they have to create said documentation as they go so they can figure out what went wrong. That kind of work is time consuming and most people don't want to pay shop rate for that kind of tedious time consuming work.

[swissarmychainsaw]

Originally Posted by hatzie

I would recommend drawing up a schematic of the wiring so when you come back to it in 3 years you can figure out what you did...
As an occasional buyer... It's a selling point to have a wiring diagram for any hot rod.
Even some custom shops will refuse to work on electrically modified vehicles without documentation because they have to create said documentation as they go so they can figure out what went wrong. That kind of work is time consuming and most people don't want to pay shop rate for that kind of tedious time consuming work.

Also it helps remember what you did a month ago!
Here are all the changes I made to the system. Hatzie gives good advice.



I had to relocate my fuel pressure regulator which WAS where the AC is now. It took me an hour to figure out where to put it. At this point I realized I needed to just quit for the day.
I asked my 11 year old buddy for some advice. And I mounted it to the firewall.

Still need to

1. Run the inlet fuel line.
2. Run the wire for the rear fan
3. Vac the system for an hour
4. Hook up rear fan switch
5. Fire it up!

[hatzie]

Originally Posted by swissarmychainsaw

Also it helps remember what you did a month ago!

I was being generous. My CRS is that bad at times but not all the time. Yet.

[swissarmychainsaw]

Per the manual the charge required for "Overhead System C-K" which I believe is GM speak for the rear system, is 5 lbs 4oz.

There are 15.3 fluid ounces in a pound, with means the ORIGINAL R12 requirement is (76.5 + 4 oz) = 80.5 oz.

My supplier (Mike) at Classic Auto Air says that R134a should be 70-80% of the original R12 charge.

Which translates to: 56.35 - 64.4 oz or R13a for this unit, or 6 12oz cans.

Mike said charging it should take a good 45 minutes. He mentioned adding 2lbs, then 1 oz at a time, watching the thermometers in the vents front and rear for "maximum chill".

It's been in the mid 80s all week, and now it's 65 degrees out!

Last run to the parts store to buy some "chilly juice" and IT'S ON!

[hatzie]

I've never had good results trying to extrapolate pounds of R12 to R134, HFC152, or R290/R600 blends.

I saved this method from some posts Jungle Eddy made about using hydrocarbon and other alternative refrigerants on a Fidonet Aircon message forum that I frequented on a dial in BBS system. Around 2001 or so. I thought it was older than that.
This method always gives me decent results no matter what refrigerant is used.

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Posted by JungleEddy on September 05, 2001 at 08:17:44: via: or 66.25.151.188

More important stuff.

How to charge an A/C system.

Note: This method will work for any automobile A/C system regardless of refrigerant type. The pressures I list here will only be correct for HC’s.

I have been trying for the past couple of weeks to come up with a “system” that would allow just about anyone to properly charge their A/C system. While this method I have developed is not fool-proof, it yields the closest thing to a perfect charge I have found. I have tested it on three “non A/C” mechanics in the past few days with great success.
First: If you have not read my previous post on vacuum, flushing, oil supply, leaks and fans etc etc, please do so now. You still need a properly assembled system to get proper cooling!

This ENTIRE process makes a few IMPORTANT assumptions!!
1. The ambient air is OVER about 84 degs.
2. You have a set of A/C gauges
3. You do not take shortcuts.
4. You are able to read and comprehend enginsh.

This process will work down to about 80 degs ambient air, but will be MUCH MUCH easier to over charge below 85 degs ambient air!! Relative high side pressures will be lower at 80 degs ambient and pressure drop after wetting the condenser will be less dramatic.

Pull a hard vacuum for a minimum of 15 minutes, 60 minutes is perfect. Static charge the system to about 65 psi while the engine is NOT running.

If you have a low pressure cut out switch on your system you will need to adjust it down to 18-19 psi sometime during this process. Personally, I find it easiest to do this about midway (now) through the charging process. Remove the connector from the switch and turn the adjustor screw about 1 full turn counterclockwise from its factory position. (counterclockwise is less psi, clockwise is more psi, 99% of the time) Start the engine and turn on the A/C, recirc, max fan, and engine at idle. Max fan is important, since it will help keep the evaporator from freezing as you charge. Charge the system slowly (if you have to!) until the compressor stays on fairly continuously at IDLE. The adjustment I illustrated above should give you a cut out psi of 12-18 psi. Watch your low side gauge and SLOWLY increase engine rpm. The low side pressure will drop slowly but substantially because you are still undercharged. Watch it drop from 20+ psi down through the teens and carefully note where the compressor cuts out. Return the engine to idle and pull the connector to the cut out switch and adjust it accordingly. Try this several times until, as the engine is slowly revved the compressor cuts out at about 18-19 psi on the low side.

The Charge:
Bring the engine rpms up to a continuous 1200-1800 rpm. Begin to add refrigerant (if you have to) SLOWLY until you notice that the air at the vents is noticeably cooler than the ambient air, say at about 65-75 degs or so.
At this point grab your garden hose and hose down the condenser; soak it once only. Your pressures will drop dramatically. The high side should drop below 150 and the low side should drop low enough to cycle the compressor, or if the switch is temporarily “jumped” the low side should be well below 20 psi. I prefer at this stage to jump the connector to the pressure switch to keep the compressor running continuously. It makes the process go much faster, but you risk freezing the evaporator. Now, watch the system pressures rise as the water evaporates and the heat in the system and stabilizes and equalizes. This can take a long time if you have a mechanical radiator fan. The point where the pressures remain relatively constant is called equalization.

Here is the key:
(After wetting the condenser) As you are watching the high side pressure rise from 160psi through (potentially) about 205psi the LOW side should REMAIN from 21-24 psi. If the high side never sees 145+psi you are still low on charge as long as the ambient is 85 degs or above. If as the high side needle swings through 160psi the low side is still below 20psi, you will add more refrigerant AFTER wetting the condenser again and dropping the pressures. Keep doing this until the low side remains at 21-24 psi while the high side swings through 160psi and finally settles at equalization (no more rise) Keep the engine rpms constant and wait for equalization (or close) each time before wetting and charging. If you are going carefully and slowly you could see a high side over 225 at equalization BEFORE you reach a full charge. The high side will DROP as you come closer to a full charge. Be aware that if you over-charge, the high side will climb again and never come down.

Note: If the ambient air is above 95 degs, stop watching the low side after the high side climbs past 205 or so. Especially if you have weak fans.

Note: Take your time and wait for equalization and water evaporation off the condenser before adding refrigerant. An overcharge can occur with no more than an extra 1.5 ounces of refrigerant!!

You can double-check your work at any time (and I suggest doing so) by waiting for full equalization and stabilization of pressures. Then, carefully MIST water into the condenser SLOWLY SLOWLY dropping the system pressures and watching for the same readings on the gauges as listed above.

When finished you should have a sweaty return line all the way back to the compressor. When the return line begins to feel chilled over the first portion of its length, you are approaching full charge. Do not forget to reconnect the low pressure cut out switch!

Do not consider your vent temps accurate until the vehicle has been driven for about 10 minutes at moderate highway speeds!!!! Idle low side pressure should not exceed 40 psi (34-38 actual) if everything is working well; good fans etc….

The idea here is that the compressor should NOT cycle when ambient air temps are above 81-84 degs.

Interesting note for tech heads: If you are charging SLOWLY. You will find at first that the high side will be at a higher pressure, after equalization, on a low charge than at a correct charge! Remember, raised heat = expansion and/or pressure.
Why: (basically)
Within a certain range, the pressure in the condenser (high side) is MUCH more affected/determined by the temperature of the refrigerant than its volume.
ALL THINGS BEING EQUAL, the condenser has the ability to lower the temperature of the refrigerant passing through it “X” amount and no more. The compressor, in compressing the refrigerant, heats or raises the temperature of the refrigerant “Y” amount. Lets say the temperature of the refrigerant entering the compressor via the return line is “Z”. So the final temperature “T” of the refrigerant that gets to the orifice/exp valve is: Z+Y-X=T
If we could lower the value of “T” the entire system would work more thermally efficiently and at lower pressures on the high side. So, ALL THINGS BEING EQUAL, you could 1. get a larger condenser and raise your “X” value or 2. lower the value “Z”.
A full charge on an A/C system will not only have enough refrigerant in it to keep the evaporator “chilled”, but JUST ENOUGH that the line leaving the evaporator and returning to the compressor will also have substantially cooled refrigerant in it THUS LOWERING YOUR “Z” value!! Hello!!
Note: Over charging will allow actual condensed refrigerant (liquid) to make it all the way back to the compressor. As we all know, you cannot compress a liquid…boom/screech.
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