New fan switch. What's the Pinout?

[pethier]

The thermostatic radiator-fan switch which came to me in the parts for my Ford Zetec engine swap is apparently inoperative.  Mick at Metric Auto sold me the only one he had in stock with the same M22 thread. Of course, the dead one has only two connectors and the new one has three (one physicaly smaller than the other two).  Mick says most such switches nowadays have three connections because two-speed radiator fans are now common.

 

I'd be happy to know if anyone has any information about this part.  Such as:

 

How is it wired in the original car?

Clarification:  "original car" means the Volkswagen cars for whom this new 3-connector part was meant, not a Birkin or a Volkswagen with a 2-connector part.  As shown in the photo, the new part is meant for a 94 to 03 Eurovan.

 

Is it a solid-state item I can damage with wrong polarity?

Edited July 29 by pethier
clarification

[7Westfield]

pretty sure this is what I have in mine, but located in the lower hose

 

https://www.ebay.com/itm/293373075512?fits=Model%3ARabbit|Make%3AVolkswagen&_skw=vw+rabbit+fan+switch&itmmeta=01K1B3VN1QQ9KXPYSCRJNEQ3HD&hash=item444e65e038:g:dHkAAOSwiM9hs4O7&itmprp=enc%3AAQAKAAAA8FkggFvd1GGDu0w3yXCmi1eHKR55QZV7SCaaiLBrhSXYN05cOR7IsoQyc%2Bj7Z9Qe%2B8Dn89sioAAluuRQ66bxF1EIxpJVG5bcDFDG2xUbZTauSDyAZZEoCslN5xcaCU9Ablrv%2FpVbMMkS24EFzERpzet8gcksXDZIi2N9hDDFmJe1ZMgR3HzC5jfGEkCDry4HEwxsxKfyGz6TEIVOzIzPhefdf7XZeo74Ms9efKJ7KmFfDr111--Dnzwf8LFAnMvI4LIzS9TEjql1T6rvt%2FMpu4eAvU5hxeQG5FRtDnjdW31Xyy3RQ%2B9Z9wfwWLrf0ro7Qg%3D%3D|tkp%3ABFBMhtHu44pm

 

Burton still has a couple of options, if you are ordering from them

[pethier]

Thanks, 7Westfield.

 

Not the question I asked, but a useful answer nonetheless.  

 

How did you know the the 1975 Rabbit was the first NEW car I ever bought?

[7Westfield]

6 minutes ago, pethier said:

How did you know the the 1975 Rabbit was the first NEW car I ever bought?

rather be lucky than good.......

 

and to your original question, I wouldn't expect your switch to be solid state, but no way to tell other than testing and seeing if smoke leaks out, unless there's a wiring diagram

[pethier]

BTW, I agree that the lower hose makes more sense, but a fan running more than needed is not something on the top of my worry list just now.

[pethier]

1 hour ago, 7Westfield said:

rather be lucky than good.......

 

and to your original question, I wouldn't expect your switch to be solid state, but no way to tell other than testing and seeing if smoke leaks out, unless there's a wiring diagram

Exactly.  That's why I was fishing for anyone who had access to an applicable schematic.

 

 

 

Edited July 29 by pethier

[MV8]

How did you determine the original fan sw was bad?

 

The eurovan sw is not solid state.

 

On the eurovan, fused power feeds through pin two (the narrow middle pin). Pin one closes at 188f, opens at 168f while pin three closes at 200f and opens at 180f. These should have a mfg tolerance of +/- 8degrees.

 

The sw controls a multi-relay box that controls a resistor bridge to have two speeds for each 450w fan having only two wires. Using high watt resistors reduces the alternator load spike and arcing in the relays (closed transition between hi and lo speed).

 

I'd connect the existing two wires to pins two and three to help ensure the fan can shut off after being tripped on. Polarity doesn't matter.

[pethier]

Thanks.  I will have more on this by tonight, I think.