Here is what I've found out pulling teeth from McCray tech support. I had an 8ft case that at some point in time was switched to 409a. 2 gravity coils fed by 1 TXV. Went thru 2 compressors in 3 years. Come to find out that the change of freon also changed the capacity. If memory serves me correct, I removed a 1/3hp condensing unit and installed a 1/2hp med temp condensing unit with 134a. Secondly because the coils have no fans, product temp is the key, not air temp. Put a cup of water in the case and leave it there. Take water temp, not air temp. As far as SH 6-8 at the coil outlet. Continue to use the LPC to control temp. I don't remember the exact settings but a cut in of 33psi(38degrees) and a cut out around 17 or 18psi(20 degrees) should be a place to start.
Officially, Down for the count
YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET
I know enough to know, I don't know enough
Why is it that those who complain the most contribute the least?
MONEY CAN'T BUY HAPPINESS. POVERTY CAN'T BUY ANYTHING