Steve B

Gosh, you are so good! You know these cars inside and out.
Speaking of which, I think problem is outside, namely low on freon.....
EC pushed:voltage LHP to grd,1st termnal = 1 v
2nd terminal = 3.8v
defrost pushed: 1st terminal= 0v
2nd terminal=12.6
jumper across LHP and compressor starts......

what do I need to check next? there are no obvious leaks indicated by oily spots near line connections. I had 1 or two cans of hot shot put in over a year ago, if low now I think I would like to change to 134a. Any special considerations with r12 and hot shot?
pull vacuum, see if it holds, inject some ester oil and then charge with 134a? I've had good success with this approach in other vehicles....

thanks for the good guidance!