Hoshizaki Commercial Series Service Manual page 27

https://appliancetechmanuals.com
9) Defrost
Temperature/Time-Initiated Defrost: Once DTh cools to 32°F (0°C), a 4-hour cumulative
Comp run timer starts. Once DTh is at or below 32°F (0°C) and 4-hour cumulative
Comp run timer terminates, MH and PH continue, DH energizes, and Comp, ConFM,
and EvapFM de-energize. Defrost Termination: DTh warms to 59°F (15°C). MH and
PH continue. DH de-energizes. 3-minute Comp delay timer starts, 8-minute EvapFM
delay timer starts (3-minutes on manually initiated defrost), and 13-minute temperature
display delay timer starts.
3-minute Comp delay timer terminates, Comp and ConFM energize. 5 minutes later,
8-minute EvapFM delay timer terminates and EvapFM energizes. 5 minutes after that,
13-minute temperature display delay timer terminates and cabinet temperature appears
on DM.
Defrost Diagnosis:
Defrost Initiation: Has DTh cooled to 32°F (0°C) or lower? Confirm DTh status. See
"IV.C. Thermistor Check." Has 4-hour Comp cumulative run timer satisfied. Check that
Comp, ConFM, and EvapFM de-energize. If not, check for 115VAC between CM C1 and
CM N5, then between CM F6 and CM N5. If 115VAC is present, CM is defective and
must be replaced. Confirm DH energizes. If not, check for 115VAC between CM H4 and
CM N5. If 115VAC is not present and DTh is in proper range, CM is defective and must
be replaced. If 115VAC is present, confirm DH amp draw and continuity.
Defrost Termination: Has DTh warmed to 59°F (15°C)? If not yet confirmed, confirm
DTh status. See "IV.C. Thermistor Check." If DTh is not in proper range, confirm DH
amp draw and continuity. If DTh is in proper range, DH de-energizes and 3 delay timers
start.
3-minute Comp delay timer terminates: Have Comp and ConFM energized after DH
is de-energized for 3 minutes? If not, check for 115VAC between CM C1 and CM N5.
If 115VAC is not present, CM is defective and must be replaced. If 115VAC is present
between CM C1 and CM N5, check for 115VAC on CR coil (terminals 5 and 6). If
115VAC is not present between CR 5 and CR 6, check continuity of HPS. If open, allow
time for HPS to reset. If HPS does not reset, replace HPS and diagnose reason for HPS
activation. See "IV.A.2.7)c) HPS Activation." If 115VAC is present between CR 5 and
CR 6, and Comp and ConFM do not energize, check CR contact continuity. If open, CR
is defective and must be replaced. If CR is good and Comp or ConFM do not energize,
check for 115VAC at Comp terminals, check Comp overload (internal on 1-section), start
components, and Comp and ConFM motor windings. Check Comp and ConFM motor
winding continuity.
8-minute EvapFM delay timer terminates (3-minutes on manually initiated defrost):
Confirm EvapFM energizes 5 minutes after Comp and ConFM energize.
13-minute temperature display delay timer terminates: Confirm cabinet temperature
appears on DM 5 minutes after EvapFM energizes.
If components fail to start after delay timer terminates, CM is defective and must be
replaced.
27