You need to borrow the R134 Ac manifold from autozone and check the pressure with AC running. If you are checking the low side w/o AC on, the static pressure seems low, mine was in the 60-70 mmHg with R12. If the pressures are ok. I would look for leaks in the system. Hopefully, all you need is to tighten up the hose line. If the pressures are low all around, then you will have to evacuate the system at a shop, then replace the leaky hose, install new r134 compatible o-ring, vacuum, and recharge the system. You must know the hi/lo pressure before working on the above.

John