Im sorry Eric. I replied but it didnt came through somehow.

What I would do is measure on the actual relay socket and using the relay pin numbering. This is my guess for your situation:

- 85 or 86 : your yellow/red (see if it toggles with e.g. connect a lamp)
- 86 or 85 : permanent ground (given that 12V above is heater on)
- 30 : red/white always on (fuse 2 engine compartment)
- 87 : yellow/black blower
- 87a : not connected

What I think is wrong in your case is the yellow/red wire not reaching your relay. I only have the workshop manual of 84-89, so this 5pin relay nowhere to find. Guess it's a earlier solution.

If all fails, have a look at the shift coupler "compartment" in the beam in front of the back seats. In my case, yellow wires are disappearing there in the harness (they were pulled through one of the holes of the handbrake, hence, I was referring to "near the handbrake" earlier).

Well,
It looks like the heater fan relay gets it's control signal from the power going to the fresh air blower. There is also a signal through the rear window relay, but I will have to figger that out also.
eric The flow diagrams take a little getting used to.

Connected to the fresh air blower? That couldnt be right.

Im not sure what you mean by the rear window relay, but very recently I happen to have installed a rear window wiper (from a 964). If you have removed that then it's perfect to control your engine compartment blower.

Or are you referring to the rear window defogger? I was thinking of that too initially, but figured that it's not practical. Have both defogger and blower on draws quite some current. Having a 2 stage switch opened other configuration, but understanding now that the 2nd stage is on an interval reduce the possibilities a lot. Furthermore, I dont want to risk any cracks in the window during the winter by connecting all elements together.

Or modify the circuitry of the defogger relay so that there is no interval and only use the center defogger element of the rear window.

Either way it not very elegant. And for you the worse case is that you have to draw a line all the way back to the engine compartment and use an extra switch or so.

I know it sounds kinds crazy. I was trying to figger out where the actual "control" signal comes from. It's not intuitive, the circuit for the powering the heater fan is simple, a couple of wires in the rear regulator panel and a relay. My conundrum comes from trying to find the signal that tells the relay to power up the heater fan.The signal wire on the flow diagram comes from the 3 lever switch on the dash, the rear window defroster switch, and believe it or not the seatbelt buzzer relay.
Eric

Here are some of the "Flow Diagrams" from the FSM:





http://i71.photobucket.com/albums/i1...DSCN7949-1.jpg

http://i71.photobucket.com/albums/i1...d/DSCN7950.jpg

http://i71.photobucket.com/albums/i1...d/DSCN7951.jpg

http://i71.photobucket.com/albums/i1...d/DSCN7952.jpg

http://i71.photobucket.com/albums/i1...d/DSCN7949.jpg
Start drinking before you try to cypher the bad boys out!
eric
P.S. 1975 USA CIS 911

Great!

V4 : Heater blower
J14 : THE relay

Blower
Bottom : red - permanent ground (due to side of diodes, odd color choice)
Top : yellow/black - to relay pin87

relay
pin87 : yellow/black - to blower
pin30 : red/white - always hot (due to side of diodes) via fuse S something
pin86 : red/black - switched hot via fuse S something (due to ignition coil N which must be switched hot)
pin85 : yellow - to the control of the starter B

The seat belt warning (SB) relay J34 is also connected to the ignition/starter switch D. I think it's like this:

Ignition key switch will control the seat belt relay in the following way.

1. Turning on ignition ('rest' position before cranking) the yellow out of the SB relay is actually connected to ground. Since the complementary side of the blower relay is connected to switch hot, it will blow.
2. During cranking the yellow out of the SB relay will provide a hot connection for the relay in the starter. Consequently, the blower relay is connected between 2 hot connections and will shut off (no voltage difference).
3. When the engine is running the ignition key will be in the 'rest' position again and the blower will run again.

Hence, the blower is always on except during cranking! Kinda strange and waste of energy. I think I'm going to wire it differently . . .

The SB relay might also switch some other things off when actual cranking is going on. Because there is a hell lot of connection for a simple seat belt warning relay, even if it has an integrated buzzer:)

Last question:
In the diagram connected to the blower relay at switched hot (ignition coil), there is a blue/yellow wire completely at the right. I got that one too. What is it for?

Hello,
I was at Parts Heaven in Hayward today, chatting with the counterman, he said the heater is switched on by the heater levers being raised. I originally thought the switch on the back of the e-brake was for the light, turns out it is for the heater motor. Gonna play about with it tomorrow. Also doing a oil cooler install, adding hard lines flex lines and a cooler, its kinda cool, aftermarket cooler from the 80's. Will post flicks after I get all the parts sorted out and in position.
Hola
eric

The heater levers next to the e-brake, that is what I found logical. What I could remember is that the connector on the e-brake really switches if the it's pulled. Then again, it was a long time ago.

Oil cooler in the front? They are really pricey or is there a cheaper alternative?

Eric. What did you end up doing about wiring the engine compartment blower?