I would say that nothing causes a coil to overheat except for a bad coil, replace the coil and see what happens.
The resistance to the electric flow through the wire coil causes heat
heating coil or fan
Heater coil could have went out.
Too much heat.
Dirty Air Filters or dirty coil on inside unit.
slavery
An electric heater coil works by passing an electric current through a resistive material, usually made of metal. The resistance in the material causes it to heat up, generating heat that warms the surrounding air in the heating system.
Condenser coil
When the system over charges. When the evaporator coil gets smaller.
what causes a Honda CRV to over heat
why do aaa batteries overheat
Heat from the Sun.