A low refrigerant charge is one of the most common causes of a frozen evaporator coil on a heat pump. When there is not enough refrigerant in the system, it cannot effectively absorb heat from the indoor air, causing the coil to freeze up.
Dirty Air Filter
A dirty air filter can restrict airflow across the evaporator coil, causing it to freeze up. When the air filter is clogged, the evaporator coil does not get enough warm air to melt the frost that forms on it.
Defective Reversing Valve
The reversing valve on a heat pump changes the direction of the refrigerant flow so that the system can operate in either heating or cooling mode. If the reversing valve is defective, it may not switch properly, causing the evaporator coil to freeze up in heating mode.
Low Airflow
Low airflow across the evaporator coil can also cause it to freeze up. This can be caused by a number of factors, such as:
* A closed or blocked vent
* A dirty blower wheel
* A defective blower motor
Faulty Thermostat
A faulty thermostat can also cause the evaporator coil to freeze up. If the thermostat is not properly calibrated, it may not send the correct signal to the heat pump, causing it to run for too long or at too low of a temperature.
Dirty Evaporator Coil
A dirty evaporator coil can restrict airflow and cause the coil to freeze up. Dirt and debris can build up on the coil over time, blocking the fins and preventing them from absorbing heat.
