Hoshizaki Modular Cubelet Serenity Series Service Manual page 18

Condensing Unit Diagnosis: Confirm that CLPS closes. Once CLPS closes, MC
energizes, energizing Comp and FMR. If not, check condensing unit 208-230VAC
power supply, breakers, disconnects. Next, confirm 115VAC from CLPS (BR) wire to
neutral (W). If 115VAC is not present, check wiring connections and power supply.
CLPS: When PDS is energized, CLPS closes when refrigeration circuit low-side
pressure reaches 29 PSIG. If CLPS is open, check that refrigeration circuit low-side
pressure has reached 29 PSIG. If refrigeration circuit low-side pressure is too low,
confirm proper TXV operation, check for refrigerant restrictions (drier, PDS), and correct
refrigerant charge. Recover, evacuate, and recharge if necessary. If refrigeration circuit
low-side pressure reaches 29 PSIG and CLPS does not close, replace CLPS.
SLPS: If SLPS is open, manually reset SLPS. If manually resetting SLPS does not
close contacts, replace SLPS. After resetting, confirm proper TXV operation, check for
refrigerant restriction (drier, PDS), and correct refrigerant charge. Recover, evacuate,
and recharge if necessary.
HPS: If HPS is open, HPS automatically resets when refrigeration circuit high-side
pressure is within an acceptable range. If HPS does not reset (open), allow pressures
to equalize and HPS to reset. If refrigeration circuit high-side pressure does not drop,
recover, evacuate, and recharge if necessary. Before restarting the appliance, check
for dirty or clogged condenser. Once the appliance is restarted, check for proper FMR
operation and fan blade for binding. Check receiver, service valves, PDS, and drier
for refrigeration circuit restriction. Also check for proper HM operation. If high-side
refrigerant pressures have returned to an acceptable range and HPS does not close,
replace HPS.
MC: If MC energizes and Comp does not energize, check for 115VAC at MC C2 (O) to
neutral (W). If 115VAC is not present, check CLPS, SLPS, and HPS contacts. If 115VAC
is present, check MC coil continuity. If open, replace MC. If closed, check MC L1 (BK)
and MC L2 (BR) to a neutral (W) for 115VAC. If 115VAC is not present on either L1
(BK) or L2 (BR), check incoming power supply. If 115VAC is present on both L1 (BK)
and L2 (BR) and Comp does not start, check MC T1 (BK) to MC T2 (R) for
208-230VAC. If 208-230VAC is not present, replace MC. If 208-230VAC is present,
check Comp start relay, start capacitor, run capacitor, and Comp motor windings.
If FMR does not energize, check MC T3 (DBU) to a neutral (W) for 115VAC. If 115VAC
is present and FMR does not energize, check fan motor capacitors and motor windings.
If 115VAC is not present, replace MC.
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