Service Manual

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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, conrm CTh status. See "IV.C. Thermistor Check." If CTh ohm reading is in
range and Comp and ConFM do not de-energize, replace CM.
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? Conrm DTh status. See
"IV.C. Thermistor Check." If DTh is in proper range, conrm 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, replace CM. 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 (W wire). If 115VAC is present between CR terminal 4 and
neutral (W wire), replace CR.
Defrost Termination: Has DTh warmed to 40°F (4.4°C)? If not yet conrmed, conrm
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, replace CM. 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 (W wire) and
CR terminal1 and neutral (W wire). If 115VAC is present between CR terminal 4 and
neutral (W wire) and not CR terminal 1 and neutral (W wire), replace CR. If CR is good
and Comp or ConFM are not energized, check for 115VAC at Comp terminals, Comp
protector (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