[Amps] 4 wire EBM Papst fan but without using PWM

[Conrad PA5Y]

I have a couple of EBM-PABST 3254J/2H3P fans which have a 4 wire 
interface. I do not want to use PWM and while they run with just the 
positive and negative DC voltage applied they tend to change speed in a 
random way when I run my amplifier without the PWM and tacho wires 
floating. How can I ensure that the fan runs properly without using PWM? 
Can I just tie the PWM input high via a resistor and ignore the tacho 
connection?

Regards

Conrad PA5Y

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