Viconics VT7600 Installation Guide (First Release 1000 Series) - Manual (Page 22)

22
Troubleshooting guide
All models
Symptom Possible Cause Corrective Action
Absent or incorrect supply
voltage 1. Check power supply voltage between C & RC to be
from 19-30 Vac
2. Check for tripped fuse or circuit breaker
No display on the
thermostat
Overloaded power
transformer Verify that the transformer used is powerful enough
(enough VA’s) to supply all controlled devices
including the thermostat
Keyboard menu does
not access all functions Keyboard locked Change configuration parameter LOCKOUT to value
“0” to access all levels of the menu
Temperature setpoints
revert to original value
after a certain time
period Temporary setpoint option
selected 1. The thermostat needs to be in Permanent setpoint
mode for the new setpoint to be kept and memory
and used all the time
2. Go to the Set temperature menu.
3. The last prompt is setpoint type. Set it to
Permanent setpoint
Wrong mode selected Select heating mode
Thermostat in Unoccupied
mode Select Occupied Hold in Schedule hold or Override to
force the thermostat Occupied heating setpoint
Anticycle delay active Wait, the anticycling period will end and the
equipment will start
Heating setpoint is satisfied Raise the Heating setpoint
Heating lockout attained 1. Mode is locked out based on outside air
temperature
2. Change configuration parameter H Lock to value
120 °F ( 49 °C ) to by-pass lockout
Thermostat will not call
for heating
Wiring error 1. Start the Fan by forcing the Fan ON mode
2. Put a jumper across terminals RH & W1. The
heating should come ON. If it does not, verify
wiring and check if a jumper is required between
RC & RH
Wrong mode selected Select cooling mode
Thermostat in Unoccupied
mode Select Occupied Hold in Schedule hold or Override to
force the thermostat Occupied cooling setpoint
Anticycle delay active Wait, the anticycling period will end and the
equipment will start
Cooling setpoint is satisfied Lower the cooling setpoint
Cooling lockout attained 1. Mode is locked out based on outside air
temperature
2. Change configuration parameter C Lock to value -
40 °F ( -40 °C ) to by-pass lockout
Thermostat will not call
for cooling
Wiring error 1. Start the Fan by forcing the Fan ON mode
2. Put a jumper across terminals RC & Y1. The
cooling should come ON. If it does not, verify wiring
Wrong mode selected The thermostat will not
turn on the fan
Wiring error
1. Start the Fan by forcing the Fan ON mode
2. Put a jumper across terminals RC & G. The fan
should come ON. If it does not, verify wiring
Digital display shows
missing digits or erratic
segments Defective display Replace thermostat