User Guide & Service Manual
USER GUIDE
 Troubleshooting - Extended 3
u-line.com
SAFETY • INSTALLATION & INTEGRATION • OPERATING INSTRUCTIONS • MAINTENANCE • SERVICE
Testing The Main Control
If the main control is suspected of being faulty, the 
following procedure should be performed to verify main 
control for functionality.
Relay & DC Outputs
One of the primary functions of the main control is to 
operate the multiple relay and DC outputs during each 
cycle. Verify proper operation of these relays using the 
following procedure.
1. Enter “Relay Toggle” through the service menu.
NOTICE
Frequently toggling the compressor relay could 
force the compressor into overload. The 
compressor will automatically deactivate during 
an overload and will remain deactivated until the 
overload switch cools. This could take some 
time. It is important to allow the compressor at 
least 5 minutes off time between relay cycles.
2. Toggle the relay. Its related component should 
activate / deactivate with the switching of the relay. If 
it does not, test component.
Other Suspected Main Control Faults
If other components have been ruled out as being faulty 
but the unit continues to have operating issues, it is most 
likely due to a configuration error. Configuration errors 
can be cleared by restoring the unit to its factory default 
setting. Factory defaults may be restored through the 
service menu.
CAUTION
!
Precautions must be taken while working with 
live electrical equipment. Be sure to follow 
proper safety procedures while performing tests 
on live systems.
THERMISTORS
Thermistors are used for various temperature readings. 
Thermistors provide reliable temperature readings using a 
resistance which varies based on surrounding 
temperatures. If a faulty thermistor is suspected it may 
be tested using an accurate ohmmeter. In an ice water 
bath (32°F) resistance should measure 16.1 kilohms.
5K OHMS @ 77°
16.1K OHMS - 32°F ambient
Check Voltage 
At Wall Outlet
Verify Voltage At 
Main Control 
Voltage Input
Check Fuse F1
For Continuity
Replace 
Reed Switch
Replace Main
Board
Replace
Fuse
Replace
Power Cord
Alert Customer 
Of Power Failure
Is the Reed
Switch Operating
Properly?
Inspect 
Customer UI 
and Data Cable 
Connect Test Display 
Cycle Power And Check 
For Operation 
No Voltage
No Voltage
Voltage
Continuity
Operating
Not Operating
No Continuity
No
Yes
Voltage
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