Board logo

heater fan control
Mr Whippy - 7/5/08 at 10:00 AM

Right need a solution to this, I have now got a fan for the heater to replace the sad pathetic Cortina one, a mega powerful thing taken from a Jap car but don’t have any way of regulating the speed so its like force 10 out the vents and sounds like a jet or nothing

Needing some sort of dial thing with a knob to control it any ideas, was thinking maybe some sort of variable resistor say to handle oh about 20amps

What have others used?

tegwin - 7/5/08 at 10:06 AM

The older polo fans come with large resistors for variable speed...can you not use one of those?


20A seems a bit high to me...unless you are using it to blow the car along!

Mr Whippy - 7/5/08 at 10:16 AM

quote:
Originally posted by tegwin
The older polo fans come with large resistors for variable speed...can you not use one of those?


20A seems a bit high to me...unless you are using it to blow the car along!



hmm ta I have a look in the scrappy, I need something with a naff knob rather than something modern oddly enough. I haven't measured the current but it came out a people carrier (it fits the hole for the Cortina one perfectly though) and the wires get hot , their about the same gauge as my headlights

[Edited on 7/5/08 by Mr Whippy]

02GF74 - 7/5/08 at 10:18 AM

big resistor is inefficient and archaic way of doing it.

I would use a pwm module like the one in linky but this is a bit low on amps for you application - if output stage is FET, these can be parlleled up or fit a bigger output driver.

Alternatively pot, 555 device with a big power transistor could be tonked up for a bout a fiver but it is easier for me to say that than for you to make I suspect.


on ebay and ebay again

[Edited on 7/5/08 by 02GF74]

02GF74 - 7/5/08 at 10:25 AM

quote:
Originally posted by Mr Whippy
and the wires get hot , their about the same gauge as my headlights



not as weird as you may think - headlamps are about 55 W = 4 Amps so if you are quadrupling the current, what you experience is not unexpected.

britishtrident - 7/5/08 at 10:33 AM

Heater fan motors are always speed controlled by a resistor.
In the old days the resistors was mounted in the engine bay so it got some air flow over it to cool it on more recent cars the resistor is mounted inside the heater inlet duct so the air flow from the the fan itself is drawn over it.

You will need resistors in the .2 to 1 ohm range and they will handle up to at least 25 watts.

Easiest way to get the right resistors at a fair price is follow this link -- http://www.rezpax.com/

[Edited on 7/5/08 by britishtrident]

Mr Whippy - 7/5/08 at 10:34 AM

quote:
Originally posted by 02GF74
big resistor is inefficient and archaic way of doing it.

I would use a pwm module like the one in linky but this is a bit low on amps for you application - if output stage is FET, these can be parlleled up or fit a bigger output driver.

Alternatively pot, 555 device with a big power transistor could be tonked up for a bout a fiver but it is easier for me to say that than for you to make I suspect.

[Edited on 7/5/08 by 02GF74]


Getting a bit technical there…

Looking for something premade with a knob or dial like that Maplin one but higher rated

02GF74 - 7/5/08 at 10:37 AM

quote:
Originally posted by britishtrident
Heater fan motors are always speed controlled by a resistor.


wow really? never knew that; you'd have though it being 2008 and not 1948 technology would have caught up .....

Mr Whippy - 7/5/08 at 10:51 AM

quote:
Originally posted by 02GF74
quote:
Originally posted by britishtrident
Heater fan motors are always speed controlled by a resistor.


wow really? never knew that; you'd have though it being 2008 and not 1948 technology would have caught up .....


Probably down more to cost, home builders can afford to be more flamboyant, really I'd be quite happy with a bit of Dr Frankenstein’s lab

britishtrident - 7/5/08 at 11:03 AM

quote:
Originally posted by 02GF74
quote:
Originally posted by britishtrident
Heater fan motors are always speed controlled by a resistor.


wow really? never knew that; you'd have though it being 2008 and not 1948 technology would have caught up .....


Don't get me started on complexity on some modern cars you can't change the main light switch without dealer level software access. Would believe BMW store a back up copy of the cars odometer reading in the light switch and another in the key fob blippers.

neilj37 - 7/5/08 at 12:29 PM

What about something similar to what they use on a TR6.

http://www.rimmerbros.co.uk/rimmer/triumph/tr6/elec-faciacp#Dash%20Knob%20Sets

MikeRJ - 7/5/08 at 12:47 PM

quote:
Originally posted by 02GF74
wow really? never knew that; you'd have though it being 2008 and not 1948 technology would have caught up .....


PWM causes it's own problems such as electrical interference, so you need a load of heavy inductors to filter the output. It very quickly gets more expensive than a multi-way switch and resistor pack.

Mr Whippy, check if the fan assembly still has the resistor pack mounted on it, if so you just need to find a suitable multi-way switch.

Mr Whippy - 7/5/08 at 12:48 PM

quote:
Originally posted by neilj37
What about something similar to what they use on a TR6.

http://www.rimmerbros.co.uk/rimmer/triumph/tr6/elec-faciacp#Dash%20Knob%20Sets


Cheers, I'm asking a friend who has a couple of Triumphs if the switch is all I need to buy.

ta

Mr Whippy - 7/5/08 at 01:03 PM

quote:


Mr Whippy, check if the fan assembly still has the resistor pack mounted on it, if so you just need to find a suitable multi-way switch.



Afraid it's just the motor and fan I have, the donor car had a big control centre for the heater system..