Coolant Fan Speed Controller Circuit.

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Coolant Fan Speed Controller Circuit.

Postby quattrodaveuk » Tue Aug 08, 2017 6:34 am

Afternoon all,

The original coolant/radiator fan on my car has 3 speeds controlled via an old resistor pack. The resistor pack is beginning to break down (1st speed doesn't work at all) I don't really want to replace the resistor pack, I was hoping to build a PWM controller with 3 inputs, something like 30% 60% and 100%.

I understand this will have to hold a fair amount of current, and i'm a bit dubious to trust my own design, anyone with a bit more experience got any suggestions or circuit diagrams to help me move move forward on this?

Thanks

Dave
Dave.

4 Rings To Rule Them All!

1989 Audi 200 Quattro 5 Cylinder 10v Turbo - Running sequential MS3 & MS3x. Now tuning.
2011 Skoda Octavia L&K Estate 2.0 Diesel.
1998 Landrover Discovery 3.9 V8 EFi - No Mods Yet
1981 Range Rover Classic 3.9 V8 - Webber 500 Carbs - Now Sold :'(
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Re: Coolant Fan Speed Controller Circuit.

Postby billr » Tue Aug 08, 2017 2:19 pm

What is the maximum current draw of that pump?
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Re: Coolant Fan Speed Controller Circuit.

Postby Blown88GT » Tue Aug 08, 2017 4:03 pm

1988 Mustang GT, 57k miles, Orig. Owner
ProCharger 600B I/C, 12psi, FRPP Hdrs, Flwmstr F2, 3G Alt, Mk8 Fan & DCC ctl, 3.55's, Prog Sprng, Subfrms, UCA, LCA, FCA, Tokico 5-ways, CSA 16x8, Bridgestone RE760 225/50R16, Crane HI-6, Kirban FPR, DIYPNPF60, LC2, C&L76mm blo-thru MAF, 30lb FRPP
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Re: Coolant Fan Speed Controller Circuit.

Postby quattrodaveuk » Wed Aug 09, 2017 1:22 am

Thanks for the replys & links.

The fan's start up current is 50 to 55 amps & the running current is around 40 amps. So if we say maximum current of 60 amps?

Thanks

Dave
Dave.

4 Rings To Rule Them All!

1989 Audi 200 Quattro 5 Cylinder 10v Turbo - Running sequential MS3 & MS3x. Now tuning.
2011 Skoda Octavia L&K Estate 2.0 Diesel.
1998 Landrover Discovery 3.9 V8 EFi - No Mods Yet
1981 Range Rover Classic 3.9 V8 - Webber 500 Carbs - Now Sold :'(
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Re: Coolant Fan Speed Controller Circuit.

Postby Blown88GT » Wed Aug 09, 2017 10:21 am

quattrodaveuk wrote:Thanks for the replys & links.
The fan's start up current is 50 to 55 amps & the running current is around 40 amps. So if we say maximum current of 60 amps?...

If running current is 40A, starting current is 2-3 times that.
I used to do it with a relay, but it's big current draw on the alternaor. You also need the proper relay, one rated for motor loads, Bosch p/n 0-332-002-156
My Lincoln Mark VIII fan will draw continuous currents of 33A@12.0V & 42A@14.4V, and has a starting current in excess of 100A!
With PWM controller, starting current is 65A.

I worked with DCC & did some testing for him when he first introduced the FK-35 about 15 years ago, now it's an FK-45 & a host of others.
He used to sell complete fan assemblies with controller.
He owns the patent & licenses it to Derale.
DCC is a 1-man operation & is always busiest in the summer. He usually responds to email fairly quickly; if you place an order, expect a long wait & be very patient.
He's been in this business 15-20 years, probably wants to retire.
1988 Mustang GT, 57k miles, Orig. Owner
ProCharger 600B I/C, 12psi, FRPP Hdrs, Flwmstr F2, 3G Alt, Mk8 Fan & DCC ctl, 3.55's, Prog Sprng, Subfrms, UCA, LCA, FCA, Tokico 5-ways, CSA 16x8, Bridgestone RE760 225/50R16, Crane HI-6, Kirban FPR, DIYPNPF60, LC2, C&L76mm blo-thru MAF, 30lb FRPP
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