Fresh air fan speed switch working in wrong positions.

[tobsam]

Ever since I have owned my 911 the fresh air blower has never worked so I recently bought a good used fresh air blower assembly complete and fitted it in to the car today.
When I use the fan speed slider of the heater control panel on the dash the fan speed settings are working in reverse ie

Position I = fast speed
Position II = medium speed
Position III slow speed

As far as I know no alterations have been made to any of the electrical contacts on the fan speed switch on the dash and the plug that fits in to the fresh air blower can only fit in one way.

Has anyone else had this problem or would anyone know what might be the problem causing this?

I know it is not the end of the world with the fan speed switch working the opposite way round but it would be nice to have it working correctly.

[donagain1]

Looking at the current flow diagram for an '82 shows it to be rather up front in the circuit design. Three conductors between the switch and the motor to carry the battery to the motor, each connecting from a particular switch position contact on the dashboard end to a corresponding resistor (no doubt internal) on the motor end, with of course no resistor for high speed. The harness between the switch and the motor goes through a 6-pole connector. Here's the pin assignments, wire color, and function for the connector:

Pin #2 = white/green = fan speed #1
Pin #4 = white/yellow = fan speed #2
Pin #3 = white = fan speed #3 (no resistor, so it's high speed)

There may be other wires for other circuits occupying one or more of the remaining pins, but they'll have nothing to do with the blower.

This is the extent of the diagram's info, and it unfortunately does not indicate where the connector is located. Odds are it is near where the harness pokes through the firewall. A quick fix would be to simply transpose the white wire and white/green wire where they connect to the switch (or anywhere else they may be more easily accessible).

Don~

[tobsam]

Originally Posted by donagain1

Looking at the current flow diagram for an '82 shows it to be rather up front in the circuit design. Three conductors between the switch and the motor to carry the battery to the motor, each connecting from a particular switch position contact on the dashboard end to a corresponding resistor (no doubt internal) on the motor end, with of course no resistor for high speed. The harness between the switch and the motor goes through a 6-pole connector. Here's the pin assignments, wire color, and function for the connector:

Pin #2 = white/green = fan speed #1
Pin #4 = white/yellow = fan speed #2
Pin #3 = white = fan speed #3 (no resistor, so it's high speed)

There may be other wires for other circuits occupying one or more of the remaining pins, but they'll have nothing to do with the blower.

This is the extent of the diagram's info, and it unfortunately does not indicate where the connector is located. Odds are it is near where the harness pokes through the firewall. A quick fix would be to simply transpose the white wire and white/green wire where they connect to the switch (or anywhere else they may be more easily accessible).

Don~

Thanks for that Don.

If I can gain access to the plug easily enough that connects to the fresh air motor itself then I might be able to swap the position of pin 2 and pin 3 over which in theory would then have the fan speed switch on the dash working correctly, well hopefully.