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If i can get another resisitor to fit does it make any difference to the functioning of the fan? I am thinking of relocating the resisitor to make it easier to get at, like the VR under the bonnet.
I would think it would make no difference i was thinking of putting vR or so one there as they are easy and cheap to get and some are solid state.
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The resistors should only need to take the current. the fans in the latter models take more current dso a VR one should be fine n an earlier model.
The location is always in the air flow, so you will need to take this into consideration when locating the resistors. This helps remove the heat and stop them from burning out.
HQ/WB air con cars have it located in the box under the bonnet, and HK/G have them in the air duct under the glove box.
Not sure on the location on other Holdens.
Warren
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Ferry wire coils
0.4 ohms
1.1 ohms
2.1 0hms
This is measured off my spare unit. I have not seen any GMH documentation that indicated the resistance. (that I can remember)
The lower resistance when switched in series with the fan motor generates the higher speed.
n (Speed in RPM) = kn * (Vm - Rm * Ia) / �
we vary Rm with the fan switch. All you can do is "reduce" from the base speed by switching in series more resistance.
Ferry wire coils (Nickel/copper alloy) in the air flow path (to reduce heat build up) was the cheapest alternative.
If you can get ceramic resistors and calculate what the wattage require is, and they fit, you will be laughing.
You will need to know current through the motor at any speed to make the calculation of wattage and then calculate resistor wattage.
Or just give up and find a good second hand one.
Cheers
Balfizar
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thanks Warren and Balfizar am away for a while so won't be doing anything but still interested in comments.
Tried jumper across the main resistor wire and the fan operated properly so not the switch, there are 2 cmplete wires there so can calculate the resistance from them, the low speed resistor is the largest one and has a sort of casing around it,there is visible overheating on it.
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Also finding a good secondhand one is a gamble and its a real pain having to dismantle half the dash to get at so want a more reliable alternative. position is not really critical, as long as it gets a decent airflow, and doesn't interfere with the fan.
There is a description somewhere can't remember where of the resistors in the VR and the ceramic equivalent so might be a good start.
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quote:
Originally posted by johnperth
Also finding a good secondhand one is a gamble and its a real pain having to dismantle half the dash to get at so want a more reliable alternative. position is not really critical, as long as it gets a decent airflow, and doesn't interfere with the fan.
There is a description somewhere can't remember where of the resistors in the VR and the ceramic equivalent so might be a good start.
Ferry wire nickel/Copper alloy resistors have a very high wattage rating and therefore are designed to run hot. The largest/thickest wire coil IS the lowest resistance 0.4 Ohms and therefore the highest fan speed. Yes, I would be doing an engineering upgrade for that resistor bank as well, do it right and forget it. Key is the motor wattage and calculation of the require wattage for the resistor bank. Get it wrong and the resistors will either burn out to open circuit or catch fire to the blower housing.
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John, You may want to consider something like the pictures. These are metal clad resistors, which are commercially available from places like RS. Mount them on a small heatsink (from RS, Altronics, Smith Head etc.) and arrange the fins parallel to the airflow when you mount it. The resistors in the picture are 15 Watt, but this style of resistor is available in higher ratings, and in a range of resistances. This is just a mockup to demonstrate the concept. For the final version you would need to know the resistance of the existing resistors, and the rated fan current, which should be in the Workshop manual, to calculate the power rating required. Even if the existing resistor is not marked, and it is wire wound, you can usually see the break in the element and measure the resistance each side of the break to get the total original value. The resistance would not need to be absolutely accurate, as the fan will rotate slightly faster or slower on intermediate speeds for a given switch position. You could put the arrangement shown in the duct and in the airflow, or use that style of resistor mounted to a larger flat aluminium plate mounted somewhere else in the car.   Edited by user Saturday, 21 February 2015 12:28:02 AM(UTC)
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update..
Got a unit out of a vr, the resistances appear to be as close as doesn't matter to the VK, and interestingly i think the vr one could be fitted to the vK. the screw holes are in the same position, and if you remove the wire cage it should fit in the hole, only thing is a new seal around the base may have to be made, and the units have a sort of ridge around the edge which is different, the VK one is more rectangular the VR is more square.
Anyway just picked some resistors from Altronics, work out at very cheap like 80c for 5, so considering doubling up in parallel to give a bit more reliability.
GM5735 thanks for your suggestion but there just is not enough room for this arrangement, remember there has to be 3 of them.
one of the deciding factors for solid state is the ferry wire would need to be oxy or arc or spot welded, I doubt ordinary solder would carry the heat.
Balfizar I am hopeless at these technical things your mentions of kns vms and rms made my head hurt I don't even know what they are.
Many thanks though don't give up on us mate !!
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quote:
Originally posted by johnperth
update..
Got a unit out of a vr, the resistances appear to be as close as doesn't matter to the VK, and interestingly i think the vr one could be fitted to the vK. the screw holes are in the same position, and if you remove the wire cage it should fit in the hole, only thing is a new seal around the base may have to be made, and the units have a sort of ridge around the edge which is different, the VK one is more rectangular the VR is more square.
Anyway just picked some resistors from Altronics, work out at very cheap like 80c for 5, so considering doubling up in parallel to give a bit more reliability.
GM5735 thanks for your suggestion but there just is not enough room for this arrangement, remember there has to be 3 of them.
one of the deciding factors for solid state is the ferry wire would need to be oxy or arc or spot welded, I doubt ordinary solder would carry the heat.
Balfizar I am hopeless at these technical things your mentions of kns vms and rms made my head hurt I don't even know what they are.
Many thanks though don't give up on us mate !!
Resistors in parallel half, e.g. if you want 2 Ohms as a total resistance you have to put 2 x 4 ohm resistors in parallel.
R// = R1 x R2 e.g. 2 = 4 x 4 R1 + R2 4 + 4 good part is you double the wattage in // brazing or silver soldering is an alternative
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quote:
Originally posted by Balfizar
quote:
Originally posted by johnperth
update..
Got a unit out of a vr, the resistances appear to be as close as doesn't matter to the VK, and interestingly i think the vr one could be fitted to the vK. the screw holes are in the same position, and if you remove the wire cage it should fit in the hole, only thing is a new seal around the base may have to be made, and the units have a sort of ridge around the edge which is different, the VK one is more rectangular the VR is more square.
Anyway just picked some resistors from Altronics, work out at very cheap like 80c for 5, so considering doubling up in parallel to give a bit more reliability.
GM5735 thanks for your suggestion but there just is not enough room for this arrangement, remember there has to be 3 of them.
one of the deciding factors for solid state is the ferry wire would need to be oxy or arc or spot welded, I doubt ordinary solder would carry the heat.
Balfizar I am hopeless at these technical things your mentions of kns vms and rms made my head hurt I don't even know what they are.
Many thanks though don't give up on us mate !!
Resistors in parallel half, e.g. if you want 2 Ohms as a total resistance you have to put 2 x 4 ohm resistors in parallel.
R// = R1 x R2 e.g. 2 = 4 x 4
R1 + R2 4 + 4
good part is you double the wattage in //
brazing or silver soldering is an alternative
Let me try again to correct this dumb software that spacing alters after you post
RR// = R1 x R2 e.g. 2 = 4 x 4..........R1 + R2..................4 + 4
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well got the thing up and working, but left a very cooked base, its plastic and does not take kindly to oxy. silver soldered it.
will get another vk one and do a more careful weld.
might try ordinary solder next time.
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