Manitowoc S Series Ice Machine Safety Timers January 15 2015, 4 Comments

Manitowoc S Series ice machines are considered the best commercial ice machines produced.  They had just the right mix of new technology and old technology that made a reliable, long lasting piece of equipment.  The longevity of the S Series, like model SY0454A, SD0302A, SY0304A, and SY0604A, is due to the control boards ability to protect expensive components with safety timers.

Safety timers are used to shut off the ice machine, in case an ice making cycle is out of spec.  This provides protection to a compressor, that may be short cycling, or loss of water through inlet valves.  Below are the 3 main safety timers, which are indicated by flashing safety limit lights on the control board.

  • The ice machine is locked into the freeze cycle for 6 minutes before a harvest cycle can be initiated.
  • The maximum freeze time is 60 minutes at which time the control board automatically initiates a harvest sequence.
  • The maximum harvest time is 3.5 minutes at which time the control board automatically ends the harvest cycle.  When the bin switch is closed a freeze sequence initiates. When the bin switch is open an automatic shutoff sequence initiates.

In addition to these safety timers, the S Series ice maker also features a warm rinse cycle.  The warm rinse cycle allows the ice machine to defrost the back of the evaporator, where ice can form, but not harvest.  After 200 freeze/harvest cycles the control board will put the S Series into a warm water rinse.

A warm water rinse cycle is indicated on the control board.  If both the clean and harvest LEDs are on, the machine is in a warm water rinse.  It’s best to let the warm water rinse cycle continue and complete.  However, the cycle can be cancelled by toggling the ICE/OFF/ON switch to the OFF position, then switching back to ICE.

If you have Manitowoc S Series ice machine diagnostic questions, please feel free to contact Ice Maker Parts Shop at  We are happy to help with Manitowoc ice machine parts research and any diagnostic assistance.