Hoshizaki 73183 service manual Defrost Diagnosis

8)Cool Down Achieved–CTh cools to 3°F (1.7°C) below setpoint. EvapFM and MH continue. Comp and ConFM de‑energize. Diagnosis: If Comp and ConFM do not de-energize, confirm CTh status. See "IV.C. Thermistor Check." If CTh ohm reading is in range and Comp and ConFM do not de-energize, CM is defective and must be replaced.

9)Defrost

Temperature-Initiated Defrost: DTh cools to 8.6°F (-13°C). EvapFM and MH continue. Comp and ConFM de-energize.

Defrost Termination: DTh warms to 40°F (4.4°C). EvapFM and MH continue. Comp and ConFM energize. 2-minute temperature display delay timer starts. 2 minutes later, cabinet temperature appears on DM.

Defrost Diagnosis:

Defrost Initiation: Has DTh cooled to 8.6°F (-13°C) or lower? Confirm DTh status. See "IV.C. Thermistor Check." If DTh is in proper range, confirm that Comp and ConFM de‑energize. If not, check for 115VAC between CM C1 and CM N5. If 115VAC is present and DTh is within proper range, CM is defective and must be replaced. If there is no voltage between CM C1 and CM N5 and Comp and ConFM do not de-energize, check for 115VAC between CR terminal 4 and neutral. If 115VAC is present between CR terminal 4 and neutral, CR is defective and must be replaced.

Defrost Termination: Has DTh warmed to 40°F (4.4°C)? If not yet confirmed, confirm DTh status. See "IV.C. Thermistor Check." If DTh is in proper range, has Comp and ConFM energized? 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.1.7)c) HPS Activation." If 115VAC is present between CR 5 and CR 6, and Comp and ConFM are not energized, check for 115VAC between CR terminal 4 and neutral and CR terminal 1 and neutral. If 115VAC is present between CR terminal 4 and neutral and not CR terminal 1 and neutral, CR is defective and must be replaced. If CR is good and Comp or ConFM are not energized, check for 115VAC at Comp terminals, Comp overload (integrated with start relay), start components, and Comp and ConFM motor winding continuity. 2-minute temperature delay timer terminates, temperature display appears on DM.

10)MH Diagnosis: Check that MH energizes. Check for 115VAC at MH. If 115VAC is not present, check power supply and continuity of power switch. If 115VAC is present, check amp draw of MH. If an amp reading is not present, check the continuity of MH.

Legend: CM–control module; Comp–compressor; ConFM–condenser fan motor; CR–compressor relay; CTh–cabinet thermistor; DM–display module; DS–door switch; DSR–door switch relay; DTh–defrost thermistor; EvapFM–evaporator fan motors; HPS–high-pressure switch; MH–mullion heater; TXV–thermostatic expansion valve

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