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.

1 answer
There is an issue with the a/c system, have the a/c serviced.