Not quite air conditioning season yet but not really heating season either.
You turn on the furnace , you open the windows and in the afternoon you turn on the a/c. This time of year is the most difficult to maintain a comfortable temperature inside your home. The furnace is sized to keep you warm when the outside temperature is well below zero , so it makes sense that it is way too big when the temperature is in the 40’s and 50’s. And vice versa with your air conditioner. When it is 70 degrees you need a little cooling in your upper floor but the a/c is sized to keep those rooms cool when it is 92 degrees outside. In both cases, the equipment runs for a very short time to satisfy the thermostat and then your home quickly becomes uncomfortable.
Heat pumps, 2 stage air conditioners and modulating furnaces will more closely match the requirements to keep your home much more comfortable in these “in between” seasons and also zoning works its’ best this time too.