Hoshizaki KM1800SAH Long Harvest cycle

Have a look at the side of the evaporator; there is a probe (thermistor) attached to it that tells the control board when to initiate the harvest cycle. make sure it's clean and attached properly and doesn't need replacing. If hitting the float switch initiates the harvest cycle it sounds like you have a blocked/ scaled water tube or switch housing. take off the bottom of the switch assembly (black rubber bit) and clean through to the water chamber. run a cycle of descaler before trying again.

time the cycle. if it is only running about 5 minutes and going into harvest, look for sump loosing water. Look at where the unit drains (like a floor drain) while the unit is running to see how much, if any water is draining. does not take much to make an early harvest. also, sump may not be filling up completely but with just enough water to satisfy the float.

clean and dry the sensor and restart the machine. Adjust the thickness until the cubes make a plate but break apart when they fall in the storage bin

Or a bad thermostat

The hot gas valve is activated during the machines harvest cycle letting hot gas defrost the evporator. If it is "leaking by " that means that it is not fully closing during the freeze cycle causing high suction pressures and inefficient operation of the machine. And maximum freeze cycles. If that is happening it will need to be replaced by a qualified technician.

Ice makers defrost is the harvest cycle. The purpose of a defrost cycle is to clear any ice build up, right?

The way I understand how Hoshizaki machines work, the model number is usually what the unit will produce, in pounds of ice. Their manual states: "Approximate production/ 24 hours @ 70 degrees air/ 50 degrees water (incoming)" So, yours should be producing 450 pounds a day, approimately. Since I can not pin point your exact model, I found one that is close. It states: "Ice Production per cycle: 6.6 pounds, 360 pcs." Again, it is not you exact machine. Their web site does not show this model either. So this is the best info I can get for you. Hope this helps.

if you are getting 5 min freeze cycles the first place to look is the Check valve this is the white triangular housing right above your pump motor it has three stainless screws take this out there is a spring and a seat clean the seat off and then stretch the spring lightly not too much replace and see if this solves the problem.

I would not change the pump. If it runs for 3-5 minutes and stops, it has to be a control. The control board runs the freeze cycle for the first 5 minutes. This prevent "Short Cycling" of the freeze cycle. The board looks at the float after the first 5 minutes for the proper water level but should not effect the pump. If the pump does not run in the wash mode, check out the "Power/ Wash" switch. I would start there before I go spending hundreds on pump motor or control board. You may be able to get by on a $20 fix! Do this and get back to me. We will get it going.

Good Luck

(Quated From Hoshizaki Technical Bulletin)
An alarm code of 3 beeps
every 3 seconds means that the control board has shut
down on the 60 minute freeze cycle back up timer.

The “E” control board has a 60 minute timer that starts at
the beginning of the freeze cycle. If the float switch fails
to open and start the next harvest within 60 minutes, the
board will automatically start the harvest cycle. If this
occurs in two consecutive cycles, the control board will
shut the unit down on the manual reset, freeze cycle
back- up timer. The yellow fault LED marked “60 min.”
will illuminate. This safety is designed to help prevent a
freeze up of the evaporator.

Once you have identified the 60 minute alarm, there are
several things to check. Reset the alarm by depressing
the white reset button to the right of the fault LED’s.
This must be done with the power “ON”. Now check the
float switch to see if it is stuck in the up position. A stuck
float can occur if scale is present on the reed switch
shaft inside the housing. To check it, drain the water
reservoir, unplug the black float switch connector (K5)
from the control board and check it with an ohm meter
for a closed switch (zero ohms). If the float switch is
sticking, clean it with ice machine cleaner or replace it as
necessary.
An inlet water valve which is slowly leaking by during the
freeze cycle can cause a 60 minute alarm. If the inlet
water valve is stuck wide open, it is unlikely that any ice
will form on the evaporator. Check for a slow leak by
allowing the unit to cycle into the freeze cycle and
disconnecting the hose at the outlet of the water valve. If
water leaks by during the freeze cycle, the water valve
diaphragm is likely damaged or the small diaphragm bleed
port is clogged with scale. Clean the bleed port or replace
the diaphragm or entire water valve as necessary.

(I Recommend to get a refrigeration tech for this part).

Another possibility is a refrigeration system problem. You
should use normal refrigeration diagnosis procedures to
check for one of these problems. If the thermostatic
expansion valve is not feeding properly or the refrigerant
charge is low, the evaporator will not form ice as it should
and a long freeze cycle will occur. This could also be the
result of the hot gas valve not closing completely during
the freeze cycle or if the compressor valves are weak or
inefficient. An inefficient compressor however, will
usually show up first on the KM model through a longer
than normal harvest cycle. This is because of cooler
than normal discharge gas. Use proper refrigeration
practices to repair a refrigeration system problem.
While these are not the only reasons for a 60 minute
freeze cycle, they are the most common and should be
checked to resolve a 3 beep/yellow fault LED alarm.