Since your pressures are taking a really long time to equalize this tells us there is a RESTRICTION somewhere in the system. The two articles below can help you troubleshoot where your restriction might possibly be:
Normal Run Pressures:
R134: (Low) 5”HG – 5PSI (High) 85 -110PSI
R600: (Low) 10HG – 15HG (High) 45-60PSI
Restrictions Before the Drier
Low Side: Lower than Normal
High Side: Lower than Normal
Restrictions After the Drier
Low Side: Lower than Normal
High Side: Normal to Lower than Normal