First Aborted Takeoff

I experienced a first on Wednesday: an aborted takeoff.  We had started rumbling down the runway, when the pilot suddenly reduced power and applied the air brakes.  We rolled off the runway and he explained that one of his lights indicated the air conditioning system was not working but the problem was now solved, so we got back in line and took off.  I am skeptical that was the real failure indicator, but whatever it was, he was being cautious.