@phaedrux All the fans are working when I use a separate 24v power source.
Not being an electrician when I noted there was 24v pwr on bad fan -- I eneded up replacing the wiring on my fan until I realised ( dumb me ) that it should have initially read a value of 0.
I didnt realise that the fan itself might short out.. i am using 24v fan winsinn -- I did read some article about them being unreiable fans.
What can I do to prevent a short from fan blowing my mosfet?
