Ice build up on secondary evaporator coil

[hamidpia]

while experimenting for on line mechanical dehumidification, I added another evaporator coil after origional evaporator coil which was giving outlet temperature 0f 20C but after no more than 20 mins Ice starts building on secondary evaporator and its compressor and refrigerant piping, I am wondering where did I go wrong. I think I should have had less number of fins per inch. What do my freind suggest.
Best regards

[nike123]

while experimenting for on line mechanical dehumidification, I added another evaporator coil after origional evaporator coil which was giving outlet temperature 0f 20C but after no more than 20 mins Ice starts building on secondary evaporator and its compressor and refrigerant piping, I am wondering where did I go wrong. I think I should have had less number of fins per inch. What do my freind suggest.
Best regards

We need pressures and temperatures to answer in meaningful way.