Maintenance; Checking The Outside Temperature Sensor (Weather-Compensated Control Unit) - Viessmann Vitoladens 300-W Installation And Service Instructions Manual

Troubleshooting
Fault codes
(cont.)
Fault code dis- System characteristics
played
Fd Burner in a fault state and ad-
ditional fault b7 is displayed
Fd Burner blocked
FE Burner blocked or in a fault
state
FF Burner blocked

Maintenance

Checking the outside temperature sensor (weather-compensated control unit)

X3
Fig. 45
74
Cause
Solenoid coil faulty
Control unit faulty
Burner control unit fault
Boiler coding card or main
PCB faulty, or incorrect
boiler coding card
Internal fault
1. Pull plug "X3" from the control unit.
Measures
Check solenoid coil by temporarily
replacing it or by swapping coil 1
with coil 2. If fault F6 is then dis-
played, replace solenoid coil.
Check coding address 38: if the
value is at 38:33, the control unit is
faulty.
Before replacing the control unit,
check while the control unit is
switched on to see if the green
LED on the ignition unit is flashing.
If the LED is not flashing, also re-
place the ignition unit.
Press reset button R. Replace con-
trol unit if the fault persists.
Press reset button R. If the fault
persists, check the boiler coding
card and replace boiler coding card
or control unit if necessary.
Restart the appliance. Replace the
control unit if the appliance will not
restart.