So our central unit is about 5-6 years old in a 2 story w/ basement house. Cools beautifully during the entire day. Sometimes even too cold, to the point I put a sweater on indoors. But late night around 12-1am and onwards until morning the AC just doesn’t turn on. I’ve been miserable for weeks now because I end up waking up in the middle of the night almost everyday, walk downstairs and turn the thermostat down more (even tho it still says the temp it was set at). Downstairs feels cooler, thermostat will say what the temp is suppose to be set to but upstairs feels really hot (warm air rises I guess).

And I know for sure the AC doesn’t turn on to maintain that temp at night because you always hear the constant AC hum/airflow during the day. I work late nights sometimes and that thing doesn’t turn on the entire night. Yet the thermostat says the same temperature. We have a pretty simple thermostat that only controls temp, turn on heat/cool. There’s no settings for timings at all.

For context, I’m in southern Ontario and the weather daytime is 80s F (25-30C) and drops to mid 60s F (20C) at night

Why would this be happening? I’ve been searching all over but can’t seem to figure it out. Someone help a brotha get a good night sleep!