Worcester Bosch Greenstar 24i Mk4 system boiler that is locked out.

[StevePatts]

Hey Folks.
I have a Worcester Bosch Greenstar 24i Mk4 system boiler that is locked out. The boiler was working correctly, then the gas supply was turned off (to service another appliance) but the boiler was not turned off. I assume that the boiler tried to cycle on and off as requested by the remote timer.The gas was turned off for 2-3 days.

The boiler is in an outhouse and the outside temp fell to around freezing for those 2-3 days. When the power is turned on, the pump runs but the fan does not start. The main indicator light starts flashing blue after about 15-20 seconds. The system pressure is at about 1.5bar. I checked the condensate syphon trap and pipework and there is no blockage. The outside temp is back to about 10degC.

It would be great if someone could let me know the start permissive for the fan to start? Can you advise any other things for me to try?
Thanks in advance

 

[Aquarius]

Did you try just re-setting it? Is the flue clear?

 

[StevePatts]

I re-set it a few times (switched off at the breaker) and also checked the flue - all clear.

Since posting earlier, i have checked the voltage at the fan. I'm getting 240V at eh fan but no movement - so i'm now thinking the fan is my problem

 

[StevePatts]

Ok, so I changed out the fan. the fan works - up to a point.
The unit starts up as such....
1. Start request
2. Pump start ok and continues running
3. Fan pulses on but does not stay on !!!
4 Fan continues to pulse (short burst - about 1/10 of sec) about every 10 seconds
5. continues like this - no ignition.

Any suggestions?