Lengthy update and diagnosis of the situation.
I will never waste money on another variable orifice, ever, for now and all time to come.
When I very gently tugged on the orifice, before I even got a squeeze on the pliers, the entire screen portion came out by itself; at this point, my heart sagged into my stomach.
I used a 4" deck-screw and managed to piece-by-piece coax the remaining pieces out; I would screw the point of the deck-screw into the broken orifice until it got a grip and then latch on the vice-grips and give it a pull; counting the top screen that came loose so easily, it came out in four pieces.
I was about half expecting the screen to be choked with black ****; but, the screen and the various pieces of the variable orifice valve were clean as a whistle.
I poured a couple ounces of PAG46 down the tube, dipped the new RED orifice in the bottle of PAG, and inserted the new orifice as deeply as it would go.
It still needed to go another inch or so; but, when I pushed just a wee bit harder, the plastic cage began to collapse.
Try as I may, that new orifice was not going any further; so, I just let the protruding end slip inside the end of the hose.
It would not go completely into the inside diameter of the hose-fitting and collapsed somewhat, sort of like an accordion.
The screen remained intact and it looked to me like it was not obstructing the flow any more by being a bit collapsed; and, seeing as I had no other alternative anyway, I tightened everything up and pulled a vacuum.
While I was watching Gunsmoke, my trusty old Harbor Freight vacuum pump pulled the system down to 25"HG.
When Gunsmoke was over, I went out and closed the valve and shut off the pump.
I went back in and watched another episode of Gunsmoke and checked the gauges; the needle was still holding steady on 25"HG.
Vacuum alone pulled in the first two 12-ounce cans of R134a.
I fired the engine, turned on the A/C, and installed the third can.
I read somewhere that my system required 44 ounces total of R134a.
However, before I connected that 4th can, I had a look at the two milk-hauler thermometers that reside in the dash vents; both were holding a steady bone-chilling 26* American; I made an executive decision and decided not to add that 4th can.
The truck had been sitting all day in direct sun.
At the time of installing the refrigerant, the ambient temperature was a pleasant, unusually un-humid 78*
The inside of the cab was 114* and you could hatch an egg in there.
Once I got the 3rd and final can installed, like I already stated, the vent temperature was 26* and there was a thick coat of frost on everything from the evaporator to the low side of the compressor.
Low side gauge reading was 12-PSI; High side was 145-PSI
Just as I was giving under the hood a quick tool check before closing the hood, I noticed that I had not yet closed the heater-core valve from last winter.
If that heater valve had been closed while I was taking my readings, I bet it would have gotten another four to six degrees colder at the dash.
When I got everything put away and the hood closed, I looked at the in-cab thermometer and it said 56*; a couple weeks ago, I would have been tickled to have had 56* in the evaporator-core housing.
So, from all indications, my refrigerant pop-off valve blowing off was due to a failed variable orifice valve.
For what it is worth, I did not replace the pop-off valve and it remains leak-free; I actually saw it blow steam at least thirty different times and untelling how many times it did so and me none the wiser.
Thanks, everyone, for your help, support, and input while I was troubleshooting and diagnosing this situation.
It may quit tomorrow, but she sure is blowing cold now; actually, better than it has ever been.
Thanks for reading.
