Chadco,

Try this for determining switch contacts:

Take a continuity meter (VOM) and attach one lead to the "+" terminal on the new switch.
Place your knob on the new switch.
Starting at CCW, fully left position, off position, rotate the switch knob through all 3 of the "on" positions and check for continuity at each of the other 4 terminals.

If you find something like this:
Position - Off, no continuity at any of the 4 terminals IV, I, II or III
Position -1, continuity at IV and I
Position -2, continuity at IV and II
Position -3, continuity at IV and III
Then you know that:
A) terminal "+" is your power wire to support the feeds to the evaporator motor and the thermostat via the new switch, and
B) "IV" is for the wire from the new switch to the thermostat, and
C) the sequential fan speed terminals will be "I" for low, "II" for medium and "III" for full fan speed.

Try this for determining which of the 3 wires from the motor correspond to 3 various speed terminals at the switch.
1) Turn on your ignition key to the accessory position and use a test light or VOM and determine which of the wires is "hot". Attach this wire to the "+" terminal on your new switch.
2) Attach the green jumper wire from the thermostat to the new switch terminal "IV".
3) In your picture it appears you had a 'black'? wire attached to the thermostat, that would be circuit wire that feeds power to your ac front condenser blower motor relay (if you have one) and the compressor clutch; turning both on and off as the thermostat's contacts make and break.
4) Assuming you are now left with 3 wires to connect to the new fan speed switch, with the ignition key on and the new fan speed switch set to its first 'on' position, corresponding with terminal "I", take each of the remaining wires and touch each one separately to terminal "I" on the back of the switch. You should be able to determine which of the 3 wires is low speed, medium speed and full speed, and then match them accordingly to terminals "I", "II" and "III".

I sense that you might find at the evaporator motor 6 wires:
A) Yellow is low speed, a Red is medium speed, Orange is full speed.
B) And, 3 other wires, another red, another yellow and a brown. If you connect the brown with the yellow, the remaining red wire is the ground and the motor will turn in one direction. And, if you swap the brown with the red, the yellow becomes the ground and the motor turns in the opposite direction.
You may have something like this explained above if it is bi-directional motor with 3 speeds. Or if there is not the set of 3 wires suggested in "B" above the the motor would be single directional motor with 3 fans speeds; however not commonly found.

KerryM. You are correct on one point, the drama increases the thread length and distracts the reader's focus. However, you are not Solomon, you are not the moderator, I run my business as I feel it should be and any reader with half a brain knows better as to what goes on here, I don't put up with Wwests nonsense and nor would I put up with yours, so go pound salt!

While I hate being a shill for Kuehl you would be better off, and an easier task, buying Kuehl's PWM controller. Typically inclusive of very detailed instructions, according to..

The photo is further proof of the poor design and manufacturing practices of Porsche during much of the air-cooled period, often reminds me of Lucas Electric.

The switch contacts/connector lugs are overheated and burned because of poor switch connection practices. The spade lugs should not only be crimped to the wires but also soldered. But even with that the heat for high current draw due to the resistance of the "slip-on" connector results loss of tight connections over time.

http://forums.pelicanparts.com/uploa...1424190137.jpg

Chadco,

Mr. Wwest brought up a good point. You may want to check the amp draw of the motor speeds (amp meter in series with the motor wires and the new switch) before finalizing your connections, but then again it is was a 25+ year old switch. The old switch appeared to have zinc plated terminals, however your new switch has silver plated terminals; as Mr. Wwest pointed out.... make sure the female spades are snug.

Bully Mr. Wwest. Bully!

All fixed !
 

I used the schematic and the continuity meter to find the neg of the new switch. It is number 4, and + is well +. Then of course speed 1,2 ,and 3 correspond to blade 1,2, and 3. With the system all in place as per factory schematic everything works perfectly. My only question is on the A/C relay it shows the ground (85) going down to fuse # 11? My wire (85) goes directly to ground of the body and the system is working properly. Is there any reason I should move that wire (85) from ground down to the top of the fuse on #11 ?

You might want to use a set of pliers to squeeze the spade lug female connectors back together for a tighter fit, better electrical connection, to the switch.

Chadco,

If things are working fine... then don't break them.

I'm not the expert on the 911 electrical design, however some might say
that if you want a starter to get all the power it can while cranking... then
kill the power to everything else. Hence, if cranking the starter kills the
ground side of the AC relay then it would .... kill the power to the AC relay
so that the AC is momentarily 'turned off' while cranking.

You are done with this thread, enjoy and move on! ;)

Thanks for all the help fella's!
As usual the members of this site have gone above and beyond to help get these beauty's back on the road😃