I had the exact same thing happen last month. The a/c was set for 79 and the upstairs temperature was 85 when I went up to bed. The fan ran constantly until we turned it off. The next morning, I went outside and checked the circuit breakers. They're in their own box mounted to the exterior of the house, near the two units. (We have two zones) Sure enough, one of the breakers had been "tripped." I turned both to "off" and then back to "on" and haven't had a problem since, even with temps in the 100's.
Try this before you do anything else. Saved me a service call fee.
My cousin is an HVAC specialist who says that it happens when there's a lot of electricity demand or storms. The power coming into the house has spikes or brownouts that you might not notice in the lights, but are enough to trip the breaker. If it happens more than once, then he said to check all the connections because it could be a wire has loosened up due to heat. I am not going to do that - I'll buy him dinner in exchange for his making the 45-min trip to my house, lol.
Try this before you do anything else. Saved me a service call fee.
My cousin is an HVAC specialist who says that it happens when there's a lot of electricity demand or storms. The power coming into the house has spikes or brownouts that you might not notice in the lights, but are enough to trip the breaker. If it happens more than once, then he said to check all the connections because it could be a wire has loosened up due to heat. I am not going to do that - I'll buy him dinner in exchange for his making the 45-min trip to my house, lol.