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We get these type of emails and calls all the time:

I burnt out the (brand new) controller that came with my Derale fans, and wished I had seen the comments on youtube about your setups.  Would appreciate a recommendation for which controller you'd recommend for my setup.


I have a twin 12" rear mounted puller fan on my rock crawler powered by a cammed 6.0.  The fans cool great when they're running, but the Derale fan controller never worked right and then burnt up on a hot day when the fans were running hard.  


What controller would you recommend of yours to purchase for that type of setup?  


Thank you for the help,




I could have sworn that I thanked you for the delivery and let you know who happy I am with your quality (Auto Cool III) product. I can’t find the email I thought I had send and am now forwarding you some pictures of the initial installation. Bottom line is with your PWM controller managing my two 2000CFM fans I have no problem keeping cool even in the middle of the Arabian Sea with AC blasting in stop and go traffic! Thanks again and keep up the great work!

Regards, Greg     


Hi Darryl, 

You can publish the following review if you choose to. 


Car: Volvo s60 Turbo 

Year: 2005-2007

Location: Malaysia


Symptom: Original radiator fan comes on at 40% even when engine is cold & maintains as such and goes to 80% speed once the air condition kicks in. 

After much investigation, it seems that this in the nature of the car for this type of year and its comparable with similar cars of this vintage. I even paid for some online advises but to no avail. 


My main concern was the fan noise and the durability of the fan running at such high speed which could shortly kill the fan motor. Volvo has been known to have problems with the fan module and its USD 600 for a replacement set. Apart from the technical aspect, its a nuisance when the car is idling at the porch or at public areas. Heads gets turned my way as if a small aircarft is on the runway. 


With the 85 Amp controller, the issue was resolved. Fan noise eliminated and car is kept cool at the same time. My best recommendation for such an install after a performance remap. 


On a side note, Volvo gives out a CEL if the original Purple PWM wire is left dangling. Connect it back to the original fan module (even a faulty one) with only the big ground cable intact. You can disconnect the big red cable to the volvo module. 


I am very pleased with the unit and the online support that Darryl gave. Hes really a gem. If anyone has a similar predicament, dont hesitate to go this route. Its money well spent as the OEM parts could easily justify the autocoolguy-module purchase. 


James Yap

Malaysian dealer for RICA Netherlands



Hello Darryl,
Just wanted to let you know your Auto Cool III arrived safely about a week ago and I finished the installation over the past weekend. I am very impressed with the quality and attention to detail of the unit. This is something you don't see all that much anymore, unfortunately.
Everything is working as it should and the coolant temp stays nice and steady with the AC on full blast at extended idle, will let you know how it holds up when it reaches summer when we see temps in the mid 40s Celsius. Think Death Valley in mid summer with high humidity on top. Probably similar to Chu Lie, but no rain.
I will send you some pictures of the installation or I can send you a link to a FB page where I posted the install.
Thanks again for a great product!

Greg in Bahrain    


Hi Darryl


Just an update on the NB-100 after 6 months. It has been working  great! After 4 years of trying different temp switch and relay combinations, I wish I had purchased one of your controllers sooner.


The adjustable set points are brilliant. I have it on a 1994 Suburban 5.7L with GM oem dual fans from a 2006 donor. My favorite part is the AC trigger with temperature override. Thanks again!


Tony in Costa Mesa


            First I’d like to say I truly love my new Auto Cool III 125 controller. It is truly a pleasure having it on my 67 El Camino.   I have had electric fans on it for about 5 years now and have gone through 4 iterations of controllers from Derale (maker of my fans). All of their controllers have failed in one way or another. Yours just seems to exude confidence and say “I got this, drive on”.


            Again thanks for such a great controller.

            Billy Craddock

            Sulphur (hot) Louisiana



Hello Darryl:
Hey mate, 
my Auto Cool III still running great after 4 years.


I wanted to ask how I could run only 1 fan until it gets hot and then flip both on. I have both Taurus fans running strong and that takes 30+ amps, if you knew a way I could use half until needed.   And is the Auto Cool unit supposed to get hot?  Because mine ran super hot under the hood, so I moved it into the cab/dash where it's only warm to the touch

Regards Justin




I absolutely have to have one of your controllers. Would you have an estimation of how long it would take to receive one in Queensland Australia? It's a little urgent (Derale unit died, no more Derale for me and I'm due to go racing) and need to find a route to take quickly. Thank you.



Sean Hartman


Hello and greetings from Germany

After I have had a bad experience with a Derale PWM controller, I found on the Internet your products and would like to buy an Autocool 85 PWM Controller with the Inline Copper Sensor.   In the gallery on your website I've seen some cars from England (nice Jaguar E-Type) and Australia and I hope that you also sell to Germany and want to know the shipping costs.

II drive a 72 Scamp with 417 cui Procharger engine with 16” SPAL fan and Fanshroud. The belt-driven fan is no longer able to cool the engine in stop and go traffic.

Best regards

Andreas Köhne



Hello Darryl
Been looking hard for a pwm controller for the Lincoln Mark VIII fan in my Healey replicar. All I see is bad reviews on the internet about units from the big name companies that don't work or no service after the sale.   I really like what I see with you and your company.

Brad Grems


Hello Darryl:


Today I have my first ride with the new Auto Cool 85 fan controller. We had 86 degrees and the water temperature never went above 200 degrees.  Usually at these temperatures, the water temperature was always too high, especially in stop and go traffic, but today there was no trouble and I could enjoy the ride. Thanks for this great product. I have the controller already recommended my Mopar-Friends. 






Hello Darryl


I have a '66 mustang with an electric fan.  The fan is a single unit but fairly large (Derale-16926).  Derale lists the fan as having an amp draw of 24 amps, but at startup, I pop the supplied 30 amp fuse every time.  I have to run a 35 amp fuse to keep it from blowing at start up.


I have been using the Derale 16749 fan controller.  It works well initially, but after a few months, I end up melting the wires leading to the relay.  I have gone through 2 of these units.  I have the controller set so it comes on when the water temp is around 180 deg F or when the AC compressor kicks on.


I am interested in your controller.  I am looking for reliability.  Do you think your product will work well for me?  I will have to mount it in the engine bay near the battery.



Fred Robertson






I have looked thru your website and most of your information and videos. I will probably be ordering one of your AUTO COOL 85 controllers. You seem to have a lot of information about your products and they look like they are designed and built to exceed their intended usage. I'm wanting to get a good working, dependable fan controller that I can count on for many years of trouble free service. My car is a 72 Chevelle with all new wiring and a new GM performance ZZ 454 engine, and a new Powermaster 150 amp alternator, plus just about every other new part I could put on it.


I recently purchased and installed a new aluminum radiator and new Derale dual high output fans 16928, which have about a 50 amp usage together. Without looking much further than the Derale website I also purchased one of their "high amp controllers" 16789. After installing everything, doing a few test just idling the controller failed. Something internal in it popped and smoked it.


The included circuit breaker did not protect it. The #1 fan would not turn on and the #2 fan would come on immediately as soon as the car was started no matter what temperature. Was going to exchange it for another one when I saw the Derale PWM controller 16795. I installed the 16795 controller and it seemed to work ok after several tests idling the car up to temp and with the A/C. Also continued to work after a short drive. On the first time of extended driving, about a hour or so, the controller stopped working and the temp gauge started to rise.   Luckily I had wired in a emergency power on switch so I would not get stranded somewhere

if the controller failed. Got back home and did a little testing and the controller does not work in any condition. Did not appeared smoked or burnt like the previous one.


In my opinion the Derale controllers might have a higher success rate with a single fan. But I'm done trying to find one of their controllers that should work as described. After reading several reviews about others having the same or similar problems with Derale and other controllers I don't want to waste my time and money on inferior products. I want a controller that works like it is supposed to and will hopefully last as long as I have the car.


Your products seem to be highly recommended and it sounds like they do the job they are advertised to do. I just thought I would contact you and see if the AUTO COOL 85 would be a good controller for me and any other information you could offer? Also, if you have any opinions on why the Derale controllers have problems and seem to fail so often? I have a feeling they are just over rated for the components inside them and they just fail.


I'll probably be ordering one of your AUTO COOL 85 controllers soon. Any information is appreciated.


Thank you,


Mike J.




I installed the pwm 85 in my 2002 Ford Focus a week ago.  This little box of yours is a miracle!  My lights no longer dim/blink, the alternator no longer chews up the belt, the car is much cooler, the idle is much better and hopefully I will get more than a month out of the alternator.


I kept searching the internet for answers on why this Ford Focus model had such a high failure rate of alternators and electrical issues.  Eventually I found your site and the pwm fan controllers.  I wish I found it sooner,  I was just about ready to deep six this car.   I can't believe this little box fixed all those problems.  I love that it's made in America.



Michael Runnels

Sandwich, Massachusetts


IHi Darryl,


The controller arrived today, fitted it this afternoon and WOW what an amazing bit of kit!   Car has never been so stable temp wise even when it had the original viscous fan. It doesn’t vary more than about 5 of degrees even when the aircon is on.   Mightily impressed.


I know it’s exactly what you designed it to do but it’s rarity these days for things to work like that, does exactly what it say on the tin. Real quality build as well, no sign of plastic anywhere!   Just wanted to let you know how pleased I am with it.


I do have one question though, I had a small LED set up as a telltale to let me know the fan was running before. It ran off of the switched side of the previous fan relay, obviously easy enough when the fan was on/off but now it’s effectively live all the time  running by PWM the LED stays on

all the time, thought it might work by running it from the neg side but that shows on all the time as well


It’s not a deal breaker but it would be nice to keep the function if at all possible, is there any way to get an on/off signal source?

I thought maybe something from the sender but didn’t want to tap into that and upset the signal or blow it.


Thanks in advance and once again superb bit of kit. There is nothing even remotely like this in the UK.


Very best regards



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