Mile SZ 2498, Service Manual, Page: 56 / 164

To check if the VFD is operating itself or not. Let the engine
temperature go near the red band. Stop the engine. The
moment the engine is stopped the fan blade should also stop
rotating. If the fan blade is still rotating then the VFD is not
engaged.
To confirmed the VFD fan is engaged or not follow the below
procedure.
:-
When the temperature reaches to app. 105
0
C [1-2 ‘O’
Clock position of needle] , run the engine at around 1600 rpm.
That time the fan pulley speed is appr. 2000 rpm. Check the fan
speed by using non contact type tachometer. It should be
around 1800 rpm.
VFD Checking