Customs 48 chevy pickup old air product AC system

installed one in my truck per instructions. all connected correctly, had a service center charge the AC. gauges show charged, air is not very cold at all. What should the AC air temp be at the vents?
Engine cooling system is good to go. Engine runs at 190 degree ish.
has anyone had problems with these units ?

 

I have an Old Air system in my F1 and it works well but you can't have any flow through the heater core for the
AC / evaporator to cool the air. Make sure the heater valve (manual, electric or vac) is shutting off coolant flow to the core.

 

Also need to have good airflow over the condenser up front. It has to transfer the heat as much as possible for best cooling in the evaporator portion.

 

Temp at the vent should be able to get to low 40s pretty easily I believe.