When is frost formation likely to occur on evaporator coils?

Frost formation on evaporator coils is most likely to occur when there is a refrigerant deficiency. This is because a shortage of refrigerant can prevent the evaporator coil from absorbing heat effectively. As the coil becomes less efficient at removing heat, the temperature of the coil drops. When the temperature of the coil falls below the freezing point of water, moisture in the air can condense on the coil and subsequently freeze, leading to frost formation.

This situation can create a cycle of inefficiency, as the frost buildup will further reduce the coil's ability to transfer heat, potentially leading to reduced cooling capacity or even system failure if not addressed. Ensuring the system is properly charged with refrigerant is critical for optimal operation and prevents such frost-related issues.