Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Attach FGA to fan pressure test point
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Observe U-gauge as the fan runs during the
appliances self check (30 secs),does it show
a pressure of approximately -3.0mb or greater?
Note:
Pressure will read as negative.