Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum

Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum (
-   General Technical Chat (
-   -   Solution to cooling fan resister failure??? (

winterbeater 04-10-2012 08:47 AM

Solution to cooling fan resister failure???
Getting warmer here in Michigan. The old Focus I bought over the winter is starting to overheat. All good when moving (runs at 94C), but idling at a stop, it gets up to about 114C before the fan kicks on. I've read a lot of threads here (thanks for the help all) and I'm confident that the problem is the famed resister. Some of the threads have been asking for cheap work-arounds, etc., as the resister costs about $50.

Why not just solder a jumper wire into the burned out resister to bypass the burned out element? Or even cutting off the plug (drastic) and connecting the two wires together. A lot of vehicles don't have two speed cooling fans. Either on or off. The fan will be noisier on high and kick on and off more often, but to me that is not a problem.

Has anyone tried this?[dunno]

Magus2727 04-10-2012 09:55 AM

Not sure if any one has tried it, but thoughts...

With them on High all the time you may have higher current spikes and possibly blowing fuses if your always jumping from static off to full speed...

The life of the fans may drop or fail sooner as they are working at a higher duty cycle for a longer period of time

longer warm up time = longer time of the motor running on a non "optimal" fuel chart

what vehicles are you referring to when "lot of vehicles don't have two speed cooling fans."? Those that don't that I know of have a mechanical clutch fan which is the "low speed" fan....

a_2000_se 04-10-2012 12:13 PM

The engine would still maintain operating temperature in the lower range but.....

The fuse may be your number one problem (30A), followed by melting your wire harness 'somewhere' if you try replacing a 30A fuse with a 50A fuse.

Wouldn't recommend it.

Would recommend fixing the original problem correctly.

amc49 04-10-2012 03:06 PM

Look at the supplied schematic, the system is already able to take the power, just more noise and fan wears out faster. Possible idle quality issues with bigger current spike from standing start off.

Simply wire direct to miss the resistor will do it.

Magus2727 04-10-2012 03:10 PM

^^^ that assumes that the wire gauge through the low speed relay is the same gauge as that through the high speed relay. what I would do instead is wire it in a "OR" configuration so the low speed relay is actually just turning on the high speed fan relay. that would be the correct way to bypass the low speed.

emsvitil 04-10-2012 05:37 PM

If you're worried about using a 50amp fuse, replace the 30 amp fuse with a 30 amp circuit breaker..........

emsvitil 04-10-2012 05:39 PM

Also, the resistor is usually fine; it's the spade connectors that get burnt up from the POS connector. Just dremel them clean.

winterbeater 04-10-2012 08:00 PM

Thanks for all the feedback. I researched a little more and agree that most of the OEM fans are two speed.

Wire gage in the current low speed circuit would be important. I didn't realize that low speed had it's own fuse. I'll check that out and verify juice to the plug. I was thinking that when I pulled the resister out, it would be fried. Time for the VOM. And clean connectors.

Seems like wearing out the motor would be the biggest negative.

a_2000_se 04-10-2012 08:06 PM

I think we're missing something here.

The Fan Resistor is a current limiting resistor/ dropping resistor. That may be why the 'low speed' circuit only needs a 30A fuse.

The high speed circuit has no series resistor, the Fan Resistor, and needs a 50A fuse.

If you short out/bypass the Fan Resistor you may exceed the 30A fuse value.
If you replace the 30A fuse with a 50A fuse you may exceed the wires current rating associated with it if it is not the correct gauge wire.

Paladin 04-11-2012 03:51 AM

ive found tht msot of the resistors fail on my car after a couple years of being blasted with rain and whatever else makes it through the radiator. i jsut make sure i have one NIB at home waiting for the next one to fail. 50 bucks every couple of years isnt so bad. (its more like a preventative maintanence thing. i jsut do it by habit now. )

All times are GMT -5. The time now is 12:10 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.1
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.