95 civic air conditioning issues

My wifes car, a 95 ex, is a great one. Never gives her problems, has been well taken care of its whole life. The ac was serviced less than two years ago. At the end of last summer, it had an intermittent problem with the ac blowing warm or hot air. It continues to do it to this day. It usually occurs if the cabin has become hot from sitting, or if the ac runs for quite a while. I have been told that it is probably the ac thermostat going bad and shutting the compressor off.

FYI the system is full and no leaks are currently detected anywhere. Any thoughts would be appreciated. I'm all for a hot wife... just not a sweaty one! Thanks.