What does thick frost on the suction line indicate?

Thick frost on the suction line is an indication of potential flooding in the evaporator. When the evaporator coil gets too much liquid refrigerant entering it, it can overwhelm the ability of the coil to vaporize the refrigerant properly. This results in a situation where excess liquid refrigerant travels back to the compressor, leading to frost formation on the suction line due to the cold temperatures associated with the liquid refrigerant and the reduced temperature of the line itself.

In normal operation, the suction line should not develop thick frost as it indicates that the system is not functioning efficiently. Therefore, the presence of thick frost can serve as a signal that there are issues within the refrigeration cycle, specifically related to the evaporation process and refrigerant management.