I have an AIRE FLO model AF90MPE075U3 furnace. Its 9 yrs old. I set the AC to 75 degrees on the thermostat before going to bed. When I got up in the morning the thermostat said 78 degrees, so it never got to 75 because I have a 2 degree variance set. It's a RobertShaw digital thermostat. I investigated a little as I had to get to work. The outside unit fan was running, there was condensation along the copper pipes, (which are insulated) but not frozen anywhere. I shut the furnace off and figured I'd look into it more when I got home.
I turned on the AC when I got home and noticed the blower fan on the furnace was cycling on and off. It would run for about a minute and shut off. It did this several times. The outside condenser fan is running fine. This is leading me to believe it is something within the furnace vs the AC. When the blower motor does run, the condensation is coming out the tube from where the evaporator is like its suppose to. By the way it's a closed system, no access panels to the evaporator. I would have loved to look inside and seen if something was plugged, I've read they get dirty and need the fins cleaned also.
So I took off the front cover off the furnace and the LED green light is flashing like a "heartbeat", meaning normal operation. So I'm not getting any fault codes. I know I'm going to end up calling a repair man, but if it was simple like a capacitor or even the blower motor. I'm handy and can fix, but I'm no HVAC gal. I'd just like to get in the right direction as why the blower fan on the furnace cycles on and off, when it should be a steady "on" as to get the house cooled. The thermostat has an on and auto switch and it does it in both.