4-step switch to 3-step fan Connection: Connection to 5.7kw heating package : B - Plus = 12V circuit - From the battery / ignition voltage L - Low speed - Yellow cable from the heating package M - Medium speed - Orange cable from the heating package H - High speed - Red cable from the heating package C - This terminal is activated when any of the 3 fan stages is activated. Then there is +12V on this pin. (used to start AC/turn on indicator light) NOTE A resistor is used to control fan speed unless the fan / fan motor has this built in. The resistor gets hot and should be mounted in the fan duct for cooling.