Dispatched for a no cool. Call back for a maintenance that was done earlier today. Arrived to find inside running but outside not running. Opened up electrical panel and found external transformer defective. I used 24 V from the furnace to power the motherboard outside. When system came on, I checked the refrigerant charge. I found it to be low refrigerant. I performed a leak on evaporator and determined that it is leaking. I am leaving an estimate for replacement for the 5 ton box evaporator coil. Cecilia paid with a credit card today. $5275. Evaporator coil to be installed on the 25th of this month.