VOLTAGE AT FAN FROM PCB (POLARITY CHECK)

Mains Power Off

Gas Off

Set Multimeter to AC Volts

CH Demand

WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure

Mains Power On

Carry out a polarity check on the fan terminals, test each terminal to earth then to each other.

Note.
Voltages wont be present if boiler enters lockout, if lockout occurs before test is complete, restart test from set appliance state.