AIR COOLED CHILLERS
TROUBLESHOOTING GUIDE
31
6) No LED H1 blinking light on NG3 Board
a) Check power supply cable an connection.
b) Check if the power supply voltage is into the specified limits: 24Vac +/- 10%.
c) Check for fuse F1, replace with 1AT/250V if blown.
7) No display of leds on User Interface Board
a) Check serial cable integrity.
b) Check serial cable connections on both the User Interface Board and the Main Board.
c) Check correct and tight insertion of jumpers JU1 and JU2 on the Main Board.
d) Check correct and tight insertion of jumpers TU1 and TD1 on the User Interface Board, main and/or auxiliary
board.
8) Auxilliary board not responding to commands
a) Check if LED H1 on Auxilliary board is blinking , if not go to point (6).
b) Check serial cable integrity.
c) Check serial cable connections on both the Main and the Auxilliary boards.
d) Check that jumpers JU1 and JU2 on the Auxilliary boards are not installed.
e) Check correct and tight insertion of jumpers TU1 and TD1 on the User Interface Board, main and/or auxiliary
board.
9) Analog Outputs not responding
a) Check Analog Output cables integrity (for short-circuit).
b) Check Analog Output cabling and connections.
c) Check if the power supply voltage is into the specified limits: 24VAC +/- 10%.
d) Check the fuse F1, replace with 1AT/250V if blown.
10) Digital Outputs not responding
a) Check Digital Output cables integrity (no short-circuit, no open-circuit).
b) Check digits Output cabling and connections.
c) Check if the power supply voltage is into the specified limits: 24VAC +/- 10%.
d) Check the fuse F1, replace with 1AT/250V if blown.
11) Serial Communication with Remote Monitoring Control not Functioning
a) Check the serial cable connected on plug-in board IS-485 mounted on the Main Board.
b) Check if the plug-in board is correctly mounted on the Main Board.
c) Check if jumpers X5 and X6 on the plug-in board IS-485 are correctly installed.
d) Check if jumpers X17 and X18 on the GATEWAY board are correctly installed.
