User Guide & Service Manual
USER GUIDE
 Troubleshooting - Extended 5
u-line.com
SAFETY • INSTALLATION & INTEGRATION • OPERATING INSTRUCTIONS • MAINTENANCE • SERVICE
FAULT SYSTEM DIAGNOSIS GUIDE
Error Solution 1 Solution 2 Solution 3
No Comm Inspect Customer UI and Data 
Cable (if defective replace entire 
door)
Zone T Open Inspect zone thermistor 
connection. Replace if necessary.
Inspect main control wire harness 
for splits or breaks. Repair split or 
cut cabling.
Evap T Open Inspect evaporator thermistor 
connection. Replace if necessary.
Inspect main control wire harness 
for splits or breaks. Repair split or 
cut cabling.
Amb Thrm Open Inspect ambient thermistor 
connection. Replace if necessary.
Inspect main control wire harness 
for splits or breaks. Repair split or 
cut cabling.
Zone T Short Inspect thermistor cable for pinch 
points or damage. Replace if 
necessary.
Inspect wire harness from main 
control board for pinch points or 
damage. Repair split or pinched 
cabling.
Evap T Short Inspect thermistor cable for pinch 
points or damage. Replace if 
necessary.
Inspect wire harness from main 
control board for pinch points or 
damage. Repair split or pinched 
cabling.
Amb Thrm Short Inspect thermistor cable for pinch 
points or damage. Replace if 
necessary.
Inspect wire harness from main 
control board for pinch points or 
damage. Repair split or pinched 
cabling.
Temp Hi 6H+ If excessive frost is also noted, 
inspect door and door gasket for 
proper seal and alignment. 
Inspect evaporator fan for proper 
operation. 
Inspect refrigeration system. 
Reference the System Diagnosis 
Guide.
Temp Hi 12H+ If excessive frost is also noted, 
inspect door and door gasket for 
proper seal and alignment. 
Inspect evaporator fan for proper 
operation.
Inspect refrigeration system. 
Reference the System Diagnosis 
Guide.
Temp Lo 6H+ Inspect main control for proper 
relay operation. 
Inspect refrigeration system. 
Reference the System Diagnosis 
Guide.
Temp Lo 12H+ Inspect main control for proper 
relay operation. 
Inspect refrigeration system. 
Reference the System Diagnosis 
Guide.
Door Open 5M Verify door closes properly. Inspect cable arm, verify presence 
of magnet, verify proper operation 
and movement or arm.
Inspect reed switch wiring.










