I have a fan controler with high temp shut off.is there a way to test the fan controler while not on the burner?

If it's a combination fan limit control with two wires on the left marked fan and two on the right marked limit. The line side wire on the switch will be hot all the time when the heat rises it closes the witch and gives power to the load side, if the blower fails to come on or doesn't move enough air it will open the limit side to kill 24v going to the gas valve. The easiest way is to turn your heat on and see if you get power to the load side when it reaches its fan on temp.

Not really a safe way. You can rotate the control by hand to see if the safety kills power to the burner BUT you take a chance on causing the control to be out of calibration. They are not designed to be turned by hand.

If you have a fix disc type you might be able to heat it and cause it to trip but unless it has a little red reset button chances are you will damage it because sometimes the non push button type will not reset on there own and then you will have to but a new one.