my m8 has got a 52 plate st170 and his heater blower switch only works on level 4 , he bought a new switch but still only works on level 4 ? has any1 had this problem before? or knows what it could be? thanks for ur help and time.

 

I would say its the resistor pack that controlls the heater motor speed. On every heater motor setting apart from max resisters are used to reduce current to the motor therefore slowing it down. Only max heater speed is not regulated so to speak.

Bri.