'73 450 SLC A/C blowing 70 degrees
 

I put in a new compresser, dryer, condenser, hose and added a 10' fan in addition to the 8'.

I converted it to 134a myself. When I couldn't get the temp down I took it to three different shops and no one can get the temp down. I even tried that Frez 12 and the lowest it got was 65 degrees. Any ideas?

I read someone mention a sanden. Where can I find one?

There are a couple of sensors as well as the Schraeder valve that you are supposed to upgrade when you convert. There are a lot of posts on the main forum on this.

Try flushing the evaporator with methylene chloride -- you may have a big slug of oil in the bottom, restricting flow. The mineral oil in the R12 systems isn't very soluble in R134a.

What are the low and high side pressures when operating? You did evacuate and verify that you are leak-free, correct?

Peter