General Troubleshooting Guide - Sub-Zero 700 Series Service & Parts Manual

Complaint
Warm compartment
temperatures (continued).

GENERAL TROUBLESHOOTING GUIDE

Possible Cause
Incomplete defrost
Poor evaporator air flow.
NOTE: To initiate a manual defrost,
see defrost section at front of
Troubleshooting Guide.
1. Faulty door sensor (700 TC/I,
700TF/I only), or faulty reed
switch (all models).
2. Evaporator fan faulty.
3. Evaporator fan blade obstructed.
4. Defrost terminator faulty.
5. Defrost heater faulty.
6. Evaporator thermistor faulty.
CAUTION! Low voltage.
DO NOT apply 115 volts.
NOTE: Evaporator thermistor ter-
minates defrost at 52
700TF/I, 700BF/I only).
7. Evaporator sump drain tube
blocked.
8. Drain tube heater faulty (700TC/I,
700TF/I, 700BF/I only).
1. With door shut and reed switches
depressed, check for 115V across P7 &
P5 at control board. If 115V is present,
repair wiring at door sensor or reed
switch, or replace door sensor or reed
switch.
2. With door shut and reed switches
depressed, check for 115V across P9 &
P5 at control board. If no 115V, repair
wiring at evaporator fan or replace
evaporator fan.
3. Clear obstruction.
4. Check wiring to terminator, then check
terminator resistance. If the evaporator
is below 30
closed. If above 70
Repair wiring or replace terminator if
faulty.
5. Check for power to heater, then check
resistance of heater. Resistance should
be 20-30 ohms. Repair wiring or replace
evaporator assy.
6. Check wiring and resistance of evapora-
tor thermistor. Resistance should be
approximately 32500 ohms at 32
10000 ohms at 77
replace evaporator thermistor.
F (700TC/I,
o
NOTE: For models 700TC/I, 700TF/I,
700BF/I prior to serial #1201766, remove
evaporator thermistor. This will defrost
evaporator every 6 hours of compressor run
time with a 20 minute dwell.
7. Clear foreign material from drain tube.
8. Check wiring and resistance of drain
tube heater. Resistance should be 1900
ohms. Repair wiring or replace.
5-3
AIR FLOW
Correction
F, terminator should be
o
F, it should be open.
o
F. Repair wiring or
o
F,
o