Stu Cool,
HTML Code:
 http://www.csgnetwork.com/r134apresstempconv.html
Heres a site with a interactive chart that you can enter different psi's for
134a and get the proper evaporator coil temperature.

And there is a lot of other information there on all sorts of suff.

Pat, I don't think that is your restriction, the restriction I'm talking about is on the high side, (inlet side) of your exspansion valve, where there is a small screen in their that gets plug up with dirt and prevents you valve from metering properly. If you are able to Isolate or disconnect the compressor on both sides high and low from the metering device, you can take a tank of nitrogen and blow back threw the exspansion valve on the low side to the high and most of the time you can open up the restriction.
Note: at 15 psi looks like a evaporator coil of 14.94 degrees F. I hope this helps.