My A/C isnt blowing as cool as it use to so I thought I would check the pressures to see if it was getting low. On the low side port with an ambient temp of ~85 I turned my car on and the gauge jumped to 50-60psi with the compressor on. Then the compressor shut off after a while and it dropped to 40psi. This was with the A/C on full cool and fans on high. The manual doesnt really give a range for psi, only the min and max for the amount of coolant needed for the system. Do these readings seem normal or should I bring my car in for a recharge?