Shut down on
maximum freeze time
Low refrigerant charge
Add some refrigerant and
restart unit. If cycle time
improves, look for leak.
Hot gas valve leaks through
during freeze
Check hot gas valve for hot
outlet during freeze
Thermostatic expansion valve
bulb loose
Check bulb
Thermostatic expansion valve
producing very low or very high
superheat
Check evaporator superheat,
change TXV if incorrect
Compressor inefficient
Check compressor amp draw,
if low and all else is correct,
change compressor
Shut down on
maximum harvest time
Ice bridge thickness too small,
not enough ice to open curtain
Check and adjust if needed
Ice bridge thickness too large,
ice frozen to evaporator frame
Check and adjust if needed
Purge valve does not open,
water melts ice bridge, not
enough ice to open curtain
Check purge valve
Incomplete ice formation
Check water distributor for
partially plugged holes
Curtain out of position
Check curtain for swing
restriction
Curtain switch does not open
when curtain does
Check switch with ohmmeter
Machine in very cold ambient
Move machine to a warmer
location
Hot gas valve does not open
Check hot gas valve, check
controller using test mode
Harvest assist probe out of
position – ejector pin not
retracted
Check harvest assist
mechanism – spring should
retract pin
Damaged evaporator
Check evaporator surface
September 2006 Page 48
Problem
Likely Cause
Probable Solution
Diagnostics - Water Cooled