Service Manual

17
7) Defrost– The defrost icon turns on and "dEF" is displayed during defrost. There
is a 5-min. minimum defrost time, a 1-hr. maximum defrost time, and a 2-hr. defrost
interval. If DTh above 50°F (10°C) at time of defrost, 2-hr. cumulative Comp run and
2-hr. continuous Comp run defrost timers reset and defrost is skipped.
1a) Time-Initiated: 2-hr. cumulative Comp run or 2-hr continuous Comp run defrost
timer terminates (Comp energized more than 2 hrs.). Defrost icon turns on and "dEF"
is displayed. Comp icon turns off. Comp and ConFM de-energize. EvapFM icon stays
on and EvapFM continues.
1b) Manually-Initiated: To initiate a manual defrost, press the manual defrost button on
the display. Defrost icon turns on and "dEF" is displayed. If on, Comp icon turns off.
Comp and ConFM de-energize. EvapFM icon stays on and EvapFM continues.
2) Defrost Termination:
(1) DTh warms to 44°F (6.6°C). If not, conrm DTh status. See "II.D. Thermistor
Check." If DTh is in proper range. 3 min. Comp delay timer starts. Defrost icon,
EvapFM icon, and "dEF" continues. EvapFM remains energized.
(2) 3 min. Comp delay timer terminates. Comp icon turns on. Comp and ConFM
energize. Defrost icon, EvapFM icon, and "dEF" continues.
(3) 15-min. temperature display delay timer terminates. Cabinet temperature
replaces "dEF" on CM display.
Defrost Diagnosis:
1a) Time-Initiation or Manual Initiation: Time-Initiation; 2-hr. cumulative compressor
run or 2-hr continuous compressor run defrost timer terminates. Note; EvapFM
remains energized during defrost.
Manual Initiation; CM defrost button pressed.
Note: There is 5-min. minimum defrost time and a 1-hr. maximum defrost time.
(1) CM, Comp, and CondFM Diagnosis: Conrm defrost icon turns on, "dEF" is
displayed, and Comp icon turns off. If not, replaceCM. Next, check that CM 1 (C)
(V) does not have 115VAC to neutral (W). If 115VAC is present, replaceCM.
(2) EvapFM Diagnosis: Conrm EvapFM icon is on. If not, conrm DTh is below
50°F (10°C). Next, check for 115VAC at CM 5 (F) (DBU) to neutral (W). If 115VAC
is not present, replace CM.