Service Manual

19
2. Freezer
5) Startup/Cool Down– MH, PH, and DrH energize. There is a slight delay, then
Comp, ConFM, and EvapFM energize. Cabinet temperature appears on display and
5-hr.Comp cumulative run time defrost timer starts.
a) MH and PH Diagnosis: PH and MH energize at startup. If 115VAC is present, check
amp draw of PH and/or MH. If an amp reading is not present, check the continuity of
PH and MH. If defective, replace PH or MH.
b) DrH Diagnosis: Conrm amp draw of DrH. If no amp draw available, check for
115VAC at DrH black wire (BK) to neutral (W). If 115VAC is not present, check wiring
connections to DrH. If 115VAC is present, check DrH continuity. If open, replace DrH.
c) Cabinet Light Diagnosis: Open the door (upper on HS/HG), conrm CL energizes.
If not check for 115VAC at CM 2 (L) (BK) to neutral (W) and CM 6 (Y) (LED) to
neutral (W). If 115VAC is not present at CM 2 (L) (BK), conrm power supply. If
115VAC is present at CM 2 (L) (BK), check DS continuity. If DS is disengaged and
contacts are closed, replace DS. IfDS is de-energized, and 115VAC is not present
at CM 6 (Y) (LED)to neutral (W), replace CM. If DS is de-energized and 115VAC is
present at CM 6 (Y) (LED) to neutral (W) and LEDs are not on, check for 24VDC at
DCD black (BK) 24VDC wire to DCD red (R) 24VDC wire. If 24VDC is not present,
check continuity of DCD driver. If open, replace DCD driver. If 24VDC is present and
LEDs are not on, check wiring harness and wiring connections from DCD to LED.
Ifconnections are good and LEDs are not on, replace LEDs.
d) CM Diagnosis: Cabinet temperature appears on display. If not, check for 115VACat
CM 2 (L) (BK) to CM 3 (N) neutral (W). If 115VAC is not present, check power cord
connections and breaker/fuse. Conrm wiring connections are secure for both
CM 2 (L) (BK) (power supply) and CM3 (N)(W) (neutral). If 115VAC is present and
display is off, replace CM.
e) Comp and ConFM Diagnosis: Conrm Comp and ConFM energize. Ifnot, check
for 115VAC at CM 1 (C) (V) to neutral(W). If 115VAC is not present, check CTh
status. See "II.D. Thermistor Check." IfCTh ohm reading is in proper range, and
115VAC is not present at CM 1 (C) (V) to neutral(W), replace CM. If thermistor ohm
reading is not in range, replace thermistor. If115VAC is present at CM 1 (C) (V) to
neutral (W), check for 115VAC at CUR (V) to neutral(W). If 115VAC is not present,
check continuity of HPS. If open, allow time for HPS to reset. If HPS does not reset,
see "g) HPS Activation" below. If HPS is closed and 115VAC present, check for
115VAC at condensing unit power supply cord (BK) to neutral (W).If 115VAC is not
present at condensing unit power supply cord (BK), replace condensing unit power
supply cord. If 115VAC is present at condensing unit power supply cord (BK) and
ConFM is energized but Comp is not, check for 115VAC at Comp external protector
to neutral (W). If 115VAC is not present, give time for external protector to cool and
reset. If Comp external protector does not reset, replace Comp external protector.
If 115VAC is present on both Comp external protector wires, check run capacitor
(2-Section), start capacitor, start relay, and Comp motor windings. If Comp does not
start, replace condensing unit. If ConFM is not energized, check ConFM fan blades
for binding and motor winding continuity.
If Comp and ConFM are energized and the cabinet does not cool down, check for a
restriction in the refrigeration circuit, correct TXV operation, and correct refrigerant
charge. See nameplate for correct charge amount.