Air Conditioning - AC blows warm air on hot days during the day

Hello,
I have 2 units outside one serving 2nd floor and 1 serving 1st floor. On hot days during the day the 1st floor unit blows warm air whereas the 2nd floor is being cooled just fine. As soon as the temp. outside decreases cold air starts coming in. Makes no difference if the unit is off and then turned on in the middle of the day. Any suggestions?

Refrigerant pressure and temperature have a direct relationship. I would say that the unit is kicking out due to a high pressure condition during the hot outside temps. I would first clean the condensing coil and see what I have that is a pretty typical cause of your complaint. If you do not have good airflow across the condensing coil due to dirty coils the high side pressure can easily exceed the cutout point during hot weather. Could be a overcharge also but lets do that coil cleaning first.

Thanks will try cleaning and report back.