I remember the same thing last summer where occasionally it would take a number of hours for the ac to kick on after I switched to cool and the temperature was above the threshold. The funny thing is that I have no problem in the past winter with heat. The heater came on as expected right away.
Switch to this summer, my thermostat is above the threshold, my batteries fresh and my switch on cool and auto. Neither auto nor fan will trigger any action from my air conditioner. Even after waiting hours and days, no activity. I tried to go to my fuse box and reset the power which is clearly labeled to my ac until, but nothing improved.
How can I get my ac running again? I really don't want to mess with replacing the thermostat (which is a modern programmable one) and the wiring that goes with that.