TD radiator fan wiring

[veeman]

I've got the TD into the caddy now and I'm working on connecting everything back up to the engine.

I got the original TD radiator / fan with the swap and the wiring seems to be a bit different than the stock 81 diesel rad fan setup.  I'd like to use the TD combo because it's newer and the fan appears to be larger.

-The stock fan has a two wire plug / socket for the fan.  Pretty simple.

-The 1.6TD fan seems to have three wires going to it and some sort of ballast resistor mounted to the fan shroud.  Is this for a high/low fan speed?

I also notice that the radiator switch is different than the NA motor's as well.  The NA motor has two terminals, the TD seems to have three.

Does anyone have any info on how that's wired in a "real" TD?  I looked in the Bentley, but didn't immediately find an answer.

Thanks in advance.

[veeman]

Ok... this answers the question about the fan speeds...

http://vwdiesel.net/phpBB/viewtopic.php?t=149

Jake to the rescue (as always).  Not sure why I didn't see that before.

The real question is how do I make the TD two speed fan perform like my original single speed fan.  Would it be fine to simply use it in high speed connected to the NA single speed fan switch?  

I don't have that relay in question (for the speeds) and it's nice to simplify the wiring...

[SteveH]

Ok, here's what I did for what it is worth.  Being as I had to wire everything in my truck (1.6TD going into a Suzuki Samurai), I wanted to simplify everything as well.  You are correct in thinking that the fan switch with the three leads is a 2 speed system.  Basically what I did was put the fan switch in hot water and found the opening temps for the two leads (whenever there would be continunity between the first and second lead, then between the first and third lead).  I then hooked up  the fans to a relay, having the cooler of the two temps close the relay; thus turning the fans on.

[veeman]

Steve...

Did you use the TD fan itself?  How about the ballast resistor on the shroud?

If I understand correctly, you're only using the lowest temp setting on the switch to trigger the fan.

[jtanguay]

that resistor is for when the a/c is on right?

[fspGTD]

There is a wiring schematic for the TD 2-speed fan system in the A1 bentley I believe, but I can tell you the ballast resistor is present on vehicles without A/C.  I believe it is part of the lower speed circuit.

In any event, if using the high speed of the TD fan, consider adding a high-current 30amp or greater relay (stock relay is 40AMP rated I believe), to take this load off the radiator thermal switch.

The two speeds is a nice thing to have to go with the big TD fan, since the lower speed does quite a good job without a whole lot of commotion.  In the rare occasions the high speed is needed and all 350 watts kick on, holy moly you wouldn't believe the CFM of air that will flow, and it is also quite the audio event, IE: that sucker is loud!  Kinda cool though, sounds kind of like a jet engine.