Service Manual

14
6) Cool Down Achieved–CTh cools to 3°F (1.7°C) below setpoint. EvapFM continues.
Comp and ConFM de-energize. Diagnosis: Conrm Comp and ConFM de-energize.
Ifnot, and Comp and ConFM were energized longer than 2 min., check CTh status.
See"II.C. Thermistor Check." If CTh ohm reading is in range and Comp and ConFM
were energized longer than 2 min., check for 115VAC at CM C1 (BR or BK) to
neutral(W). If115VAC is present, replace CM.
7) Defrost– 6-hr. defrost timer terminates and DTh is at or lower than39°F(3.8°C),
defrost starts. If on, Comp and EvapFM icons turn off. Comp, ConFM, and EvapFM
de-energize. The defrost icon turns on and "dEF" is displayed. DHenergizes. There
is a 5-min. minimum defrost time, 1-hr. maximum defrost time, 6-hr. minimum defrost
interval, and 8-hr. maximum defrost interval.
1a) Time-Initiation: 6-hr. defrost interval timer terminates. Control module checks DTh.
IfDTh is at or lower than 39°F (3.8°C), defrost starts. Ifon, Comp and EvapFM
icons turn off. Comp, ConFM, and EvapFM de-energize. Defrosticon turns on and
"dEF"is displayed. DHenergizes. IfDTh is greater than 39°F (3.8°C), defrost is
delayed for 2 hrs. (8-hr. defrost interval timer). Once the 8-hr. defrost interval timer
terminates, defrost starts regardless of evaporator temperature.
1b) Manual-Initiation: To initiate a manual defrost, press and release the manual defrost
button on display. If on, Comp and EvapFM icons turn off. Comp, ConFM, and
EvapFM de-energize. Defrost icon turns on and "dEF" is displayed. DHenergizes.
2) Defrost-Termination:
(1) DTh warms to 41°F (5°C). DH de-energizes. 1-min. Comp/EvapFM delay timer
and 11-min. temperature display delay timer start. Defrost icon and "dEF" display
continue.
(2) 1-min. Comp/EvapFM delay timer terminates. Defrost icon turns off. Comp icon
turns on. Comp and ConFM energize. EvapFM on CRES energizes. If DTh is
at 36°F(2°C) or lower, EvapFM icon turns on and EvapFM on CPT energizes.
"dEF" display continues. 6-hr. defrost interval timer resets.
Note: If DTh is 37°F (3°C) or higher when 1-min. Comp/EvapFM delay timer
terminates, CPT EvapFM remains off until evaporator temperature is 36°F(2°C)
or lower.
(3) 11-min. temperature display delay timer terminates. Cabinet temperature replaces
"dEF."
Defrost Diagnosis:
1) Time-Initiation: Has 6-hr. defrost timer terminated? Before proceeding, conrm DTh
status. See "II.C. Thermistor Check." Manual-Initiation: Press and release the
defrost button.
Check the following:
(1) CM Diagnosis: Conrm defrost icon turns on, Comp and EvapFM icons turn off,
and "dEF" replaces cabinet temperature on display. If not, replaceCM.
(2) DH Diagnosis: Conrm DH energizes. If not, check for 115VAC at CM H4 (R) to
neutral (W). If 115VAC is not present, replace CM. If115VAC is present, check
DST continuity. If open, let cool and reset. If DST does not close, replace DST.
IfDST is closed, check DH amp draw and continuity.