AC works, then light flashes & NO AC on 1994 Toyota Camry

The green AC indicator light sometimes starts to flash after operating for a few min. The air goes from chilled to ambient temp. Engine temp is normal: newer radiator, recent flush-n-fill w new thermostat.
It has been hotter than normal in SD lately, about the same time we noticed this issue. The heat exchangers are clean.

Asked by for the 1994 Toyota Camry
There is an issue with the a/c system, have the a/c serviced.