Hey guys; been a long while since I've posted up in here. Good to see the same familiar faces kicking around.
I recently purchased a '92 Wolfsburg Edition to eventually replace my rusting-away '88. It has all the fixin's except a power top - this includes A/C.
The PO of the car decided they would replace the relay socket in the wiring harness for the Radiator Cooling Fan; you know, that one that's up front by the battery, on a bracket attached to the front of the fender. Not all-together a bad idea, but the execution could have been better, they could have used the proper VW part for it, etc. I didn't like it, so I set out to look at "reverting" or correctly replacing that socket with the proper part. But then I remembered... I have an '88 sitting right there, that also used to have A/C. Awesome.
I pulled out the cooling fan harnesses of both cars for comparison, and immediately noticed one difference.
The '92 had this extra black 1-pin connector (center of the picture), in the circuit that powers (what I thought to be at the time) the high-speed side of the fan. My first thought was that the mating connector of this was the output from the cooling fan after-run timer control unit thingy, relay 14 according to cabby-info and the Bentley. Fair enough. But what do the Bentley wiring diagrams say?
Not much... it's connector T1k on this diagram (AC, 1990+), track 8:
So the wiring diagram mentions it, but doesn't actually specify what it's connected to, just that it's there, located near the left headlight, and has two R/BK wires coming out of the single-pin housing. Okay, so we move on to the 1991+ Main Wiring Diagram, track 46:
There's T1k again, I'm not sure if the different wiring diagrams share connector numbers, but this looks right. One issue with this is that the main wiring diagram here specifies that T1k is behind the fuse panel. Another is that it specifies a thicker 1.5mm (14 gauge) wire going to it. On the car, I have at most a 16 gauge wire... it's quite small...
To make matters more confusing, the whole physical wiring harness seems to be backwards. At first glance, it looks like the high-speed side of the fan is powered by the low-temp switch, the low-speed side is powered through the relay that's triggered by the high-temp switch...wait, what's this? The Bentley diagram for A/C above says that two of the wires going to the fan are R/BK? Madness! They are clearly R/W, R/BK, and BR.
Waaaiit a second... the pin numbers of the fan connector tell the whole story.
On the fan connector in front of me, you have..
- R/W, which corresponds to high speed
- R/BK, which corresponds to low speed
- BR, Ground
On the 2-temp radiator coolant temp switch, we have..
- R/BK, high temperature switch (105°C)
- R/W, low temperature switch (95°C)
- R, fused power (fuse 1, 30A)
Ah, there we go. Well done, VW! You switched the wiring colors for the A/C car's harness, when compared to the non-A/C model. Looks like even your wiring diagram guy didn't catch it, when it came to the radiator fan!
So it turns out that yes, T1k is in fact the output from the cooling fan after-run timer relay, and yes, the main harness that has the mating connector does have a stupidly small wire size considering the load it takes, and yes, this whole system *does* control the low-speed side as intended.
Not intuitive at all. The correct wiring diagram should look like this:
But I think it could have been improved overall if VW kept the wire colors the same to begin with...
That is all.