Do you have the make and model?
biasi riva advance he 24
Ok, when the fan runs you should get a click from the air pressure switch - if you get no click then there will be a problem with the switch or the fan or the tubing in between
Sorry, I did not get the last response
THE INDICATOR LAMPS ARE NOT ILLUMINATING TO INDICATE POWER? THOUGH THE PUMP IS RUNNING
What happens if you turn down the room stat or turn on the hot tap?
nothing all I can hear is the fan running
Are you able to get the cover off and inspect the fan and air pressure switch?