Nissan Repair: 95 Nissan Pathfinder A/C freeze ups, nissan pathfinder, c button

Question
My '95 Pathfinder's A/C freezes up when operated on a hot day at lower RPM's (stopped at a light) or at a constant RPM during a long drive.  I must cycle the A/C switch on and off to keep cool.  At freeze up I get a musty smell, push the A/C button off, turn fan to max and this will defrost the under dash evep core, re-push A/C button for  cool air again.  Until another freeze up which will happen in minutes if I don't continue cycling the A/C off and on while leaving the fan operating.  Low pressure is about 50 psi on the gage and in cooler weather the system works fine.  The system really gets cool/cold, but the hotter and more humid the quicker it freezes.

Answer
Jack,

Seems like the system is overcharged.  Or, the expansion valve is sticking.  Checking the pressures first and bleeding off until you get to something like 42 for the low side might just correct the problem.  If not, then it is probably the expansion valve.  Autozone has an airconditioning book and you can get a set of gauges from Harbor Freight or the internet and check the system pressures yourself or take it to a trusted shop you have delt with before.