Hoshizaki AMERICA 73183 - Manual (Page 24)

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Defrost Diagnosis:
1a) Temperature/Time-Initiation: Has DTh cooled to 32°F (0°C) or lower? Before
proceeding, confirm DTh status. See "II.D. Thermistor Check." Has 4-hr. Comp
cumulative run timer satisfied?
(1) CM Diagnosis: Confirm defrost icon turns on, "dEF" is displayed, and Comp and
EvapFM icons turn off. If not, replace CM.
(2) DH and DrH Diagnosis: Confirm DH and DrH energize. If not, check for 115VAC
at CM H4 (O) to neutral (W). If 115VAC is not present, replace CM. If 115VAC is
present, check DT continuity. If open, let cool and reset. If DT does not close,
replace DT. If DT is closed, check DH and DrH amp draw and continuity.
(3) Comp and ConFM Diagnosis: Confirm Comp and ConFM de-energize.
If not, check for 115VAC at CM C1 (R) to neutral (W). If 115VAC is present,
replace CM. If 115VAC is not present and Comp and ConFM continue, check
CR #1 (R) to neutral (W). If 115VAC is present, replace CR.
(4) EvapFM Diagnosis: Confirm EvapFM de-energizes. If not, check for 115VAC at
CM F5 (Y) to neutral (W). If 115VAC is present, replace CM.
1b) Manual-Initiation: After pressing the manual defrost button, check the following:
(1) CM Diagnosis: Confirm Comp and EvapFM icons turn off, defrost icon turns on,
and "dEF" is displayed. If not, replace CM.
(2) DH and DrH Diagnosis: Confirm DH and DrH energize. If not, check for 115VAC
at CM H4 (O) to neutral (W). If 115VAC is not present, replace CM. If 115VAC is
present, check DT continuity. If open, let cool and reset. If DT does not close,
replace DT. If DT is closed, check DH and DrH amp draw and continuity.
(3) Comp and ConFM Diagnosis: Confirm Comp and ConFM de-energize.
If not, check for 115VAC at CM C1 (R) to neutral (W). If 115VAC is present,
replace CM. If 115VAC is not present and Comp and ConFM continue, check
CR #1 (R) to neutral (W). If 115VAC is present, replace CR.
(4) EvapFM Diagnosis: Confirm EvapFM de-energizes. If not, check for 115VAC at
CM F5 (Y) to neutral (W). If 115VAC is present, replace CM.
2a) Temperature/Time Initiated Defrost-Termination: Has DTh warmed to 59°F
(15°C)? If not yet confirmed, confirm DTh status. See "II.D. Thermistor Check." If
DTh is in proper range, DH de-energizes and 3 delay timers start. If DTh has not
warmed to 59°F (15°C), check DT and DH continuity. Next, check DH amp draw.
(1) 3-min. Comp delay timer terminates: 3 min. after DH de-energizes, confirm
defrost icon turns off, Comp icon turns on, and Comp and ConFM energize.
If not, confirm cabinet temperature is warm enough for Comp and ConFM
operation. Next, check for 115VAC at CM C1 (R) to neutral (W). If 115VAC is not
present, check CTh status. See "II.D.Thermistor Check." If CTh ohm reading is in
proper range, replace CM. If 115VAC is present, check for 115VAC at CR #4 (BK)
to neutral (W) and CR #1 (R) to neutral (W). If 115VAC is present at CR #4 (BK)
to neutral (W) but not at CR #1 (R) to neutral (W), replace CR. If 115VAC is
present at CR #1 (R) and Comp or ConFM are not energized, check Comp start
components, Comp protector (internal on 1-section, external on 2-section), and
Comp motor winding continuity. If ConFM is not energized, check ConFM fan
blades for binding and motor winding continuity.