As #8 reply states , it will drip or run a small stream if the cooling coil temperature and or drain pipe is below dew point temperature . In humid areas a 5 ton unit may produce as much a 10-15 gallons of water in 24 hours . That dew-point temperature is constantly changing as atmospheric conditions change . It's no different than the glass of iced tea causing a ugly stain on the fine wood furniture because of condensation . Some days maybe , some days maybe not , some days all day and all night or maybe not .It did not drip when cold ac was ON before. Why is it dripping now when cold ac is ON?
To better explain research - Dew point temperature .