Fan speed
 

Hey all,

I'm using a Mercedes Benz electric cooling fan on my 51, S-10 swap. I've got a 327 SBC for power. The fan is on a thermostat type switch, on at 185 degrees off at 180. My trucks runs at about 185-190 degrees most of the time so the fan runs most of the time. It works great, but it is loud. I'm thinking about putting a resistor in line to the fan motor to slow it down and hopefully quiet it down. I'm electronically challenged, what type/ size resistor do I need. How many OHMS/ WATTS etc. Thanks for any help!

Re: Fan speed
 

The inline resistors that GM used to use were large, ceramic pieces likely good for 10-20 watts IIRC. Aftermarket fans are in the 200-350 Watt range so you'll probably need a stout part. You can look at a Dorman 902-219 which is a fan resistor and wiring pigtail for a 2010-ish Focus. It's designed to bolt to the fan shroud so air moves across the resistor.

Re: Fan speed
 

Thanks, I'll check that out.

Re: Fan speed
 

If you put a resistor in-line with the fan power supply you'll always be limiting the fan. You may get a hot day in traffic where you regret it.

I would either get a new thermostatic switch with a higher on / off.

Or, I'm thinking of running a pulse width fan controller such as:

http://derale.com/products/electric-...n-probe-detail

https://www.flex-a-lite.com/accessor...ontroller.html

Derale, Flexalite, Spal and some others make them.