Fan speed resistors

[Mattimus]

Hi,

There seems to be an upgrade of the resister unit, my old one has 3 elements in a metal cage, the new one appears to have an aluminium heat sink from what I've seen. I did some testing but bear in mind that the no 2 element is blown so is only an estimate.


#1 2.0 ohms
#2 0.8 ohms
#3 0.5 ohms
#4 direct connection to fan

Keep in mind that the elements are in series so the resistance on:

1 is 2.0 + 0.8 + 0.5
2 is 0.8 + 0.5
3 is 0.5
4 is zero

Plus fan load of course.

I used a amp meter but It had a blown resistor internally which was replaced. Since then the meter is probably not calibrated correctly and I think is reading high. My readings give:

1 4 A
2 11 A
3 18 A
4 25 A

You can see an even incriment of 7A between settingsl. I would not recomment just working of a resistance value because this changes as the wire heats up so is difficult to predict accuratly from ohms law especially as the wire available is probably not a good match to the original. I'd recommend connecting an amp meter and adjust the connection point on the new wire until you are happy with the meter readings and fan speed on #1.
Don't let the motor struggle to turn the fan. Only then form the that same length of wire into an element and solder it in.

I ended up ordering a new resistor on ebay as there is no local supplier for resistance wire here. Dick Smiths postage charge is a killer on small items. The figures are estimates based on measurements but should give a rough guide to get you started.

Best of luck,
Ken

This is from an ancient thread. In regards to the part where he found the resistances of each speed, what's stopping me from acquiring resisters of those values and soldering them on?

[wortus]

This is from an ancient thread. In regards to the part where he found the resistances of each speed, what's stopping me from acquiring resisters of those values and soldering them on?

Probably not much but you would need to work out what wattage resistor you would need based on the load it disipates and air flow and how much heat will transfer from the resistor to the air. You would also need to make sure that enough heat was disipated so the solder would not melt. The original resistors are made from nichrome wires which eventually burns out. On my VN the fan only worked on a few speeds and in the end I just got a new resistor pack from Holden which had an aluminium heat sink. It was not expensive and is probably the easiest way out.

[Mattimus]

Hmm yeah sounds pretty difficult :P Might just fork out the $70 for a new resistor pack and be done with it. Cheers for the reply