Mustang heater blower motor 1965 and 1966

Here is how the heater blower motor works on the 65/66 Mustangs. If your car is an early 65, and has the center position off switch, the top drawing is how that is wired. Power comes from the fuse box to the switch, and, goes from the switch to the blower motor. If you look at the blower motor itself from under the hood, you will see three wires sticking out of it. One is red, one is orange, and the other is black. The black wire is the ground wire, and should be attached to the firewall. The other two bring power to the motor from the switch.

If your car has the off position on the switch all the way over to the driver's side, the second drawing is how your car is wired. This is a system that can be a little confusing until one realizes that it is wired backwards from the way most of the stuff in this car is wired. Most systems have power coming from the switch to the component. The heater blower motor has power coming from the component to the switch. Power comes from the fuse box and goes straight to the blower motor on the brown wire. It leaves the blower motor through the yellow wire, which plugs into the resistor on the front of the heater box. There will also be a three wire harness that plugs into the resistor which goes to the switch. You will notice that there is no ground wire in this system. The switch feeds power from one of the three wires coming into it, depending on which position the switch is in, straight into the metal of the dash. It is important that the switch be making good contact with the unpainted metal of the dash on the back side, or, the system won't work, so, if you decide to paint your dash, make sure that the switch housing is still making good contact when you reinstall it.