Hello Frank. SY CF : Communication Failure - User Interface is not able to communicate
with the Main Control Board following a POR (Power ON Reset). If the User Interface is receiving the correct voltage from the Main Control
Board but cannot communicate, the User Interface will display SY CE or SY
CF. If the Main Control Board is not able to communicate with the User Interface,
the Fresh Food lights will be off. If an incompatible replacement User Interface and Main Control Board are
installed, 12VDC will be present at RED and BLK wires to User Interface but
the unit will not operate. . If replacement User Interface and/or Main Control Board are installed and
communication cannot be established due to a wiring or circuitry issue, the
unit will act as if the User Interface and Main Control Board are incompatible
until communication is established (no display on User Interface and no
operations). 1. Verify power supply to User Interface:
a. Remove left hinge cover and verify 12VDC between RED and
BLK communication wires (cabinet side). (See Figure 3)
• If voltage is correct, verify continuity of WHT communication
wire between the Main Control Board and User Interface.
Also, verify there is no continuity between cabinet ground &
WHT communication wire.
? If correct, possible Main Control Board and/or User
Interface failure.
• If voltage is not correct, access the Main Control Board.
Locate J9-A connector on Main Control Board and check for
12VDC between RED and BLK wires. (See Figure 4)
? If voltage is correct at Main Control Board, check for
loose connections, backed out connector pins, or broken
wire between the Main Control Board and User Interface.
Repair wire, if possible, and retest.
? If voltage is not correct, proceed to step 2. 2. Incorrect or no voltage from Main Control Board:
a. Check for shorted LOW VOLTAGE components (i.e. fan motors,
damper, inverter, thermistors, etc.)
• If possible, disconnect power supply to each low voltage
component and retest for 12VDC at J9-A connector on Main
Control Board.
? If voltage is correct after disconnecting component,
replace component and retest.
? If no voltage after disconnecting components, replace
Main Control Board. No Display, SY CF or SY CE after replacing Main Control Board
and/or User Interface
1. Main Control Board is not able to establish communication with
the User Interface:
The replacement User Interface must receive communication from
the Main Control Board in order to display and initiate operations.
12VDC may be present at User Interface, but no display or
operations will occur until communication is established.
a. Verify 12VDC to User Interface (see Troubleshooting SY CF/CE
Error Codes)
b. Verify continuity of WHT communication wire between Main Control Board and User Interface.
Repair wiring, if possible, and retest.
c. If SY CF or SY CE error still exists, check for shorted low voltage components (see Incorrect or
no voltage from Main Control Board).
2. Incompatible User Interface or Main Control Board:
a. Verify the correct part numbers were installed
b. Verify part number on box and part match
? Reorder correct part if either condition above is not correct.