The answer to 'evaporator coil blowing hot air' is that the evaporator coil is not functioning properly, which can be caused by a refrigerant leak, a blocked air flow, or a problem with the blower fan. This can result in the evaporator coil blowing warm air instead of cool air.
Some common causes include a refrigerant leak, a dirty air filter, a malfunctioning blower fan, or a problem with the thermostat. In many cases, this issue requires professional diagnosis and repair by an HVAC technician. Attempting DIY repairs on the refrigerant system or electrical components can be dangerous, so it's best to call in a pro unless you have extensive HVAC experience.