Did you do that at the firewall with the lines off or through the lines? Either way , I would not have done that.

 

I got it!
It's working!

I installed the new accumulator, and connected a few of the lines...
In so doing I also re-lubricated every o-ring by hand, with some oil.
After I got that done I had a more accessible line opening.

Evidently one can't blow air when the compressor's in the way, so that eliminated forcing
it through the low side, plus a lot of R-134a would've been in the way as well...
The other way would've merely been where the clog was suspected...
So I blew air through the outgoing dryer hole, down through the firewall, I was able to get a pretty good seal.
And, got air coming out the other end.

Put it all back together, wasn't but a few connections.
Evacuated the system, dropped a few ounces of oil in it.
Still have to jump the switch...

And added 16 ounces of R-134a, didn't need a lot, just what little got lost from the first
evacuation and I guess blowing the air on through.

Pressure's a bit high, 280 on the high and 45 on the low...
But, little snow flakes are coming out the vents again.

Now the only thing left is I'm going to replace that dryer switch so I can remove the jumper.

Yup.

It will be all right.

Thanks to everyone for the information and the help.