Rad Fan intermittant - killing the battery

[Huw Powell]

> I know pin 30 is power in , and pin 87 is power out.
> I think pin 5/T (thermoswitch) is one end of the coil and 6/31(ground) is
> the other end of the coil.
> But I'm at a loss regarding the functions of pin 3/15 and pin 4. Pin 4 goes
> to the A/C programmer, so I figure this pin is internally connected to the
> coil. A/C is switched on, fan goes on.
> 
> Pin 3/15 is connected to the A/C Hi-Press sw, and the center hot lead of the
> Rad cool fan thermoswitches, and the hot end of relay 2(Rad cool fan relay
> 2nd state).
> For this circuit to work, 12 volts must always be present at pin 3/15?  Even
> with ignition off?

Some basic VAG terminal numbeing standards might help you a bit here:

"30" is battery 12v
"15" is ignition on (run and start),
"X" is the load reduction relay bus (ignition on in "run" only)
"31" is ground

Also, I'm fairly sure 87 is the switched output; on simple SPST relays, 
85 and 86 are the coil terminals.

I hope this helps a little.

PS, note, these are not the numbers that are simply consecutive on a 
switch or device that we started seeing in the late 80's on parts and in 
diagrams.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/