Evaporator coils inside a walk in live a hard life. Cleaning chemicals, salt, produce acids and constant condensation corrode the aluminium fins and copper tubing, and a pinhole leak in an evaporator is one of the more common refrigerant losses we find in San Francisco, CA.
JRC repairs and replaces evaporators, including the fan motors, blades and drain pans that go with them. Where a coil is corroded through in one spot, the rest is usually not far behind, so we will tell you plainly whether a repair is worth doing or whether replacement is the better money. Drain pans and lines get cleared at the same time, since a blocked drain refreezes onto the coil.