[ray_mcavoy]

The 4 connections on the new switch are +12V FEED, LOW, MED, and HIGH. There isn't a specific terminal for the OFF position ... the switch just doesn't pass power to any of the other 3 connections in the OFF position.

The 3 connections on the old switch were +12V FEED, MED, and HIGH. Notice there's no LOW speed terminal. That's because the wire feeding the LOW speed circuit is joined together with the +12V FEED wire at the plug. Should be 2 brown wires going to 1 terminal. That feeds power to the low speed circuit all the time since there's no OFF position.

So the wires on your existing 3-terminal plug should be:

Brown = one is +12V FEED, the other goes to the LOW speed connector on the blower motor resistor.
Lt. Blue = MED speed connection to blower motor resistor.
Orange = HIGH speed connection to blower motor.


You basically have 2 options to wire up the new switch:

(1) Leave the LOW speed terminal on the new switch disconnected. The 2 brown wires joined together at the plug will cause the motor to run at low speed when the new switch is in either the OFF or LOW positions.

(2) Separate the 2 brown wires at the plug. Identify the +12V feed wire and run that to the +12V terminal on the new switch. Run the other brown wire to the LOW speed terminal on the new switch. That'll give you full functionality of the new switch ... the motor will turn off in the OFF position and you'll still have all 3 speeds.