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AC parts

WarWagon said:
Regular with dye. Use R134a pressure switch.

Enviro-Safe R134a Replacement Refrigerant W/ Dye 6 oz Cans & Cases #1030 | Enviro-Safe Refrigerants, Inc.

For automotive and other R134a applications. Equivalent to 16 oz of R134
www.es-refrigerants.com

Regular ES on left and the industrial on the right. Note the pressure around 32F where industrial is way higher. It's ~20F when the R134a pressure switch opens. Charts are half-assed only going up to 133 degrees... Need to go up to 200F and 500 PSI where systems explode from pressure. Note the lower head pressures on the high side at 133F.

View attachment 66018
Click to expand...
You can compare this R12/R134 temp chart to the R134/ES chart and see that R12 and ES are much closer to each other at each interval, hence why I recommend using the R12 switch vs the R134 retrofit switch.
R.jpeg
 
Twisted Steel Performance said:
Thanks, I'm looking for a r12 switch now, and I have read most gm switches are adjustable, I have a new purple switch here I just need to look at it and see if there is a screw between the connection prongs...
Click to expand...
Do not use the purple switch with ES or any other HC based refrigerant. You either want the stock black switch for a 93, or you can pick up an adjustable switch for an 88 to use(the 89+ is not adjustable).
 
Alright it's time for a update....

I purchased a R12 adjustable cycling switch, changed the dryer, started charging...

After 12oz I let it run to stabilize then added another can of enviro safe...

Low pressure stayed around 32psi , compressor would cycle off and back on @ 45psi.

High pressure around 225psi and steady..

Vent air not very cool after 20 minutes, so I turned the screw on the low switch 1/2 round CCW, dropped the low cycle of*f a few pounds and vent air a few degrees cooler at best..

So after a few more times turning the screw and idle speed @ 1200rpm's the compressor now kicks out @ 22psi, high is 165-170psi and steady, after 20 minutes vent air is 34* and slight frost on the dryer, so I figured it would ice up on the highway, so I turned the screw 1/4 turn CW, the other way than I had, the low psi moved up to around 23psi... BUT ....

Now the compressor clutch wants to chatter when it kicks back in, I think the screw in the switch is out of it's happy spot due to me turning it out 2 or more full turns...

They do have a adjustable r134 switch, it had on & off psi written on it, this r12 didn't... the 134 said 21 & 45 and is adjustable from their.

I know highway will be different than sitting but I could make adjustments to the screw or use the temp adjustment on the dash when needed.

So @WarWagon .... what say you, I know you run this same stuff....

EDIT.... the one thing I don't understand is how would I know if I over charged or not ????
 
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Well, I think this low switch is bad, it cycles the clutch on and off in a 5psi range now. If the low side is at 30psi the vent air is around 55*, around 23-25 psi the vent temp comes down. The switch I have ordered is adjustable r134, on at 21 off at 40, I'll see what it does, I kinda think it's a little over charged but I don't know how to know.
 
Any progress on this Chris? I'm getting together a/c parts for my '93 dump and am going to replace condenser, compressor and drier/ accumulator as well. There's no switch on the condenser or compressor in stock form, so is the high pressure switch on the drier? Can you link to the adjustable pressure switch you're using?
 
DieselAmateur said:
There's no switch on the condenser or compressor in stock form, so is the high pressure switch on the drier?
Click to expand...

FULL STOP!!!

The high pressure switch needs to be added to the 1993's. It goes on the compressor. There is a slug in the compressor now held in by a snap ring where the switch goes: of course only install when there isn't any refrigerant or pressure in the system.

Learned the hard way the wires for the switch go back in the harness for the compressor coil about 6" so the "inline white diode" that's in the harness stays connected to the compressor coil. Do not splice the switch in on the coil side of that diode! It will arc the switch until it won't open anymore ... than the A/C system explodes during a overheat high pressure event. Like when the cooling fan doesn't come on with a cold engine.

Again the switch needs to be added to 1993's as GM omitted it believing R12 didn't need it. Other refrigerants like the higher pressure R134a do need a cut out switch.
 
WarWagon said:
https://www.es-refrigerants.com/docs/SKMBT_C28011040114110-B.pdf

Charge by weight and here is the equivalent weight chart to convert from R143A to the weight of the ES you need to use.
Click to expand...
I was wanting to use this stuff on my rig, but the last time I messed with a vehicle with this refridgerant, the pressures were lower on both the low and high to the point the low pressure compressor cycle switch had to be adjusted to compensate for it. on my 95, there isn't an adjustable cycle switch available with the metric thread that is on the accumulator. I know this refridgerant will cool it's arse off like the old R12 systems. what can be done here to account for the lower pressures?
 
A machinist is always an option- taking the metric threaded part to the machinist and bring him the sae threaded sensor you want to use- have an adapter made.
I would think searching online for an adapter first.

Another is having a port added inline that has the threads you need through adaptive hose or drill and weld into hard part of the line.

Maybe contact Vintage Air - they do classic a/c systems as well as custom units. They might already have the solution for you.

The low side safety switch, IF I understand it right is there to shut off the compressor when you loose charge- like a hole in a line and the refrigerant and the oil leak out.
So it it to keep from the compressor turning into a hand grenade over a simple leak. You could simply bypass it, but will spend a chunk more cash anytime there is a leak. I would only suggest doing this during testing phase of diagnostic when you have a gauge hooked up.

Which gives me another idea where you can adapt in the new one: make a schrader valve T fitting that you attach where the existing valve is, have another schrader valve on it for servicing, and have the 3rd port be adapted to your needed sensor.
 
@WarWagon thank you for the info. I'm a ways off from getting the system set up and am not familiar with the a/c system as a whole so your advice is greatly appreciated.

What are you referring to when you say compressor coil? I'll have to go out and look under the hood for the inline diode, the only a/c wiring the truck has is the plug for the a/c clutch right behind the pulley and the switch on the drier/ accumulator.
 
Mine was the same way when I bought the truck. only the clutch connector and the cycle switch on the accumulator. I finally found the wires that go to the high side switch that goes in the back of the compressor. it was stuffed up in the main harness that runs against the firewall behind the FFM. there was a green wire and black wire I found that were stripped and shorted together making the ac work. I ended up extending those wires and splicing in the right connector I scavenged from the pick a part yard. evacuated the ac system and installed the switch.
 
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