The invention comprises a merchandiser having a refrigerated product area with a plurality of product zones and separate air flow circulation means for the respective product zones, laterally adjacent modular cooling coils associated with the respective air flow circulation means and having a normal air flow cooling mode, and defrosting means constructed and arranged for selectively discontinuing the normal cooling mode of one modular cooling coil to effect a defrosting mode thereof during a period of continued normal cooling mode operation of another of said modular cooling coils, and thereafter defrosting another modular cooling means after re-establishing normal air flow cooling of said one modular cooling coil. The invention further comprises the method of defrosting separate modular cooling coils on staggered defrost cycles to maintain at least partial cooling air flow to the merchandiser product area at all times.