[Supras] Fan issues

[Dan Gyoba]

On 13 Mar 2008 at 19:21, Kurt wrote:

> The push button for the low-speed
> setting has never turned the fan on since I bought the car used 4
> years ago. 

This is practically guaranted to be the resistor pack.  Someone else linked the on-line 
TSRM, which has all the information that you need to replace it.

The easiest way to replace this is to buy another one.  Be careful, since it's very 
delicate.

The reason that low speed goes first is because this is the circuit that has to 
dissipate the most power, and it's the thinnest wire.  It also has to dissipate the 
power when there's the least airflow through the duct, and as such it builds up heat 
the most.

I repaired mine.  There are two ways that this is possible.

1.  Find the break in the wire and solder it.  Not so easy, because the wire is 
brittle.  The break will be tiny, and probably not convenient to get to.

2.  Replace the coiled wire.  The good thing about this is that the wire itself isn't 
so much a resistor as it is a coil.  It slows the fan more by being an air-core 
inductor than a resistor per se.  I replaced mine with some 22AWG bell wire, (The solid 
wire that has a red enamel coating arount it to insulate it.)  I wrapped the wire 
around the core of a screwdriver to form the coil, with the same number (give or take) 
as the coil that was already there.  I soldered it onto the board, and voila.  I had a 
low speed fan again.

I also replaced the medium speed coil, which I broke while trying to solder the low 
speed coil.  (Go figure.)  With the heavier gauge wire, I was afraid that the resistor 
pack wouldn't work properly.  I kind of figured that I'd have High, Higher and Highest 
for speed settings, rather than low, medium, high.

Oh, it's worthwhile to note that although there are only 3 speed settings that you can 
select manually, the automatic fan control actually has 4 speed settings.  The resistor 
pack has 3 coils in it.  high speed sends the 12V to the fan motor with no resistance 
at all.  I think that the largest coil is used in parallel with the low speed coil in 
order to produce an extra speed in between low and medium.

Dan Gyoba
'89 NA 460,208 kms, Turbo swap COMPLETE
http://www.abstractconsulting.com/~dan