Manitowoc Control Board Lights November 25 2014, 23 Comments

The lights on the Manitowoc control board can tell you a lot about what's going on with your ice machine.  Depending on which lights are lit or which lights are out can help you diagnose the problematic ice maker.  Although there are a number of different control boards, most function similarly, so I'll be discussing only the basics in this article.

Clean Light

The clean light should be lit anytime the ice machine toggle switch has been moved to the clean cycle.  This light will remain illuminated throughout the entire clean cycle.  The ice machine will not produce ice while the clean light is on.

Bin Switch Light

Most Manitowoc control boards will have a light labeled bin switch or left bin, right bin.  This light indicates when the water curtain magnet is making contact with the bin switch.  This will tell the ice machine when it is full or should terminate the harvest cycle.  If you open the water curtain or damper door, the light should go out.  Anytime that light is on, the bin switch should be satisfied and the unit should be producing ice.

Water Probe Light

The water level probe light is typically labeled WTR PROBE.  This light will light anytime water makes contact with the water level probe.  It should remain on anytime the water level is submerged in water.  Once the water level inside the water trough drops, below the water level probe, the light should go off.

Ice Thickness Light

This light will turn on anytime water comes in contact with the ice thickness control, which is mounted to the top of the evaporator.  The ice thickness light is typically marked ICE PROBE.  In some ice machines, this light is also the same light that indicates when the ice machine is in it's harvest cycle.  The light will go out after the harvest has terminated.  It is also normal for this light to flash on the control board, as water splashes and hits the probe during the freeze cycle.

Safety Limit Light

On older Manitowoc ice machines, there is a single light that flashes, to indicate which safety limit the ice machine turned off on.  However, on newer Manitowoc ice makers, each safety limit has it's own light.  These lights are labeled SL1 and SL2, which either indicate the ice machine shut off on a long freeze cycle or a long harvest cycle.  These lights are very important at helping diagnose an ice machine, as it tell you which cycle the machine was having problems in.

Identifying The Correct Part

These lights help indicate when a specific ice machine part may need replaced.  The most common parts associated with these lights are water level probes, ice thickness controls, and bin switches.  Please note that Manitowoc ice machines use different ice maker parts, depending on which model machine you have.  Be sure to confirm which part fits your ice machine before ordering and if you have any questions, please email us at