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The On Line Store Page 1 below. . . .
The On Line Store Page 1 below. . . .
The Auto Cool Guy has a better way to control engine temperature.
We use Pulse Width Modulation of your fan to control its RPM. Our sensor monitors the radiator outflow temp and adjusts the fan RPM to keep the outflow at a constant 15 to 20 degrees BELOW the thermostat temp. This way, the thermostat can regulate engine temperature. Use a laser temp gun and put the red dot on the outflow area and on a black dull surface for good results as you adjust the BLACK knob. Avoid shinny chrome surface due to temp errors. Take your time and do not rush this setting. After you have made this adjustment, you should see ROCK SOLID engine temperature. You will notice speed and motor load will effect your fan RPM - see its working.
By the way, fans with Auto Cool controllers do not KICK ON and off, leave that to the brand X controllers. Please don't tell me your Auto Cool wont KICK on.
FEATURES AND CONTROLS:
Soft Start limits inrush current with pulse width when the controller is powered up. Inrush current is a brand X controller killer when starting a fan motor from a dead stop.
A/C FAN SPEED control has a small pot on the side of the controller. When 12 volts is applied to the A/C controller pin, use a small flat blade screw driver to set this fan speed. The radiator temperature control mode will over ride the A/C fan speed automatically. If not used not a problem.
FAIL SAFE: The fail safe mode turns the fan on full RPM. The FS mode is turned on by grounding the FS pin. Use a small switch from FS to ground. You can turn FS mode on or off any time.
COOL DOWN TIMER: When you turn off the IGNIITION, the fan will keep running for a period of time to cool down your radiator and then shuts down.
FAN BUZZ: The buzz is caused by the fan blade and the armature shaft not tight.
We have found the Mark VIII fan have been reported at no buzz fans.
Our HF-125 controller runs at 7Khz to prevent the buzz but may have a high frequency tone cured by a large filter cap you see below. If your fan is brushless, use our HF controller only. The fan will vibrate at low RPM with low frequency controllers.
START ENGINE: As the motor and radiator is getting warm to hot, the fan will start turning slowly and gain RPM as the temp rises. The RPM will hold at the point of regulation set by the black knob.

The Auto Cool Guy now has these special capacitors to cure the high frequency 7,000 Hz tone in you fan. One each is included with the purchase of the HF-125 controller.
Use these caps only with the HF-125 controller if your fan has the high frequency tone problem.


DIESEL RADIATOR TEMPERATURE CONTROL
One of our early customers made this Youtube on the HF-125. At first we had a Fail Safe issue but corrected it and any that had been sold. This 7 Khz controller is one of our fastest selling controllers. Video made 2-2021
Sensor Warning: If your radiator OUTFLOW port is plastic, do not use the Standard Brass sensor. It will not get true heat transferred to the sensor! This will result in very low or no fan RPM.
I made this video of the DX-150 - how it works on the bench. It has ten LEDS that show percent of pulse width.


US ARMY ORDINANCE:
CALLED UP FOR A TOUR IN SOUTH EAST ASIA AND ASSIGNED TO THE 295TH ORD. FROM HASTINGS & GRAND ISLAND, NEBRASKA
10-68 TO 10-69. MOS: SHIT BURNER AND AMMO SUPPLY LABOR. TOUR WAS IN CHU LIE, QUAN TRI CITY AND DA NANG.

The photo on the left is the Auto Cool Guy. Location was north of Quan Tri City just south of the DMZ. When we were out of our base camp we always carried our M16s and at least 8 clips of .223 ammo with 20 rounds in each clip.
The photo on the right was taken one night outside of our hooch in Da Nang. For some reason I loaded 35mm high speed slide film in my camera and had it mounted on a tripod ready to go that night. As we were drinking beer and such, all hell brook loose and the sirens went off. Then we heard one of our NCOs telling us to get into our bunker. We answered back to this NCO that we were busy drinking and taking war photos. With my camera and standard lens I shot this time laps photo of a Cobra gun shop spraying 7.62mm rounds on the Da Nang perimeter. In the morning all the MPs found was a dead water buffalo. So you see all the fun you can have in the Army!
We have been building pulse width modulated radiator temperature controllers right here in the USA starting in 2011. We design and build quality and what the customers want!




Do you plan to drive in hot desert heat?
The Auto Cool Guy is introducing the new A/C pressure controller. It can be programmed to turn on you Auto Cool's controller A/C fan mode or the Fail Safe mode. It has 10 leds that show the percent of pressure depending on the range of your pressure sensor. The control knob can be set to trip at a level you want. The DC input is BATT, IGN, and GND. The OUT will switch to ground in the F/S mode or to +12 volts in the A/C mode. We will ship a 10 inch pressure hose and 200 PSI sensor with your order. Watch our YouTube video to fully understand how it works. One year warranty!
Greg installed the Auto Cool HF-125 in his classic 1966 Mustang.
"Installation was easy and it works like a charm…
Here is the short version of the video showing before and after." Thanks much from The Auto Cool Guy!



I completed the install of the HF-125. Started the car and all seems to
be working fine in the shop. I haven't taken the car out for a drive
yet. Attached are a few photos showing the install and some
modifications I made. I fabricated covers for the top and bottom and ran
the wiring through the side. Once I test drive the car I will let you
know what improvement it makes. It already seems to be cooling better. I
ran it quite a while in the shop and it never went over about 178
degrees. I'll call after the test drive.

Auto Cool 200 NOW IN BLACK CASE
Our most powerful PWM controller, rated at 200 amps. It has the soft
start, fail safe and the cool down
timer. Base 8 x 5.5 inches


Auto Cool DX-150
Our new push button 150 amp PWM radiator temperature controller with 10 led to show percent of PWM. It has soft start, cool down timer and fail safe. Base size 6 x 7 inches.
Auto Cool 55
Our 55 amp PWM controller with soft start, fail safe and the cool down timer.
Designed or 6 and 4 cylinder vehicles not large V8 engines,
Please watch this video before you purchase that brand X controller from that "racing company." It
will save you a lot of hassle, time and money.
The Ice Box

This small device will keep your A/C fan speed constant with your A/C valve control voltage going up and down. It will give you a constant +12 volt output to your controller's A/C input. A blue LED shows DC output. Designed for most European and BMW type cars.
Case size: 3 X 3 X 1.75 inches.
Mike in Brewster, MA is putting our Auto Cool III in this super Mopar to control radiator temperature. He has become a repeat customer.
Watch this video on our Auto Cool III controller. We have sold hundreds and hundreds of these around the world. We have them in Blue and Black, let us know the color you want.

HF-125 INSTALLED
"The unit is perfect. Finally got it all buttoned up and it is keeping things nice and cool. Figured I’d send over a pic of the install - took a bit of fab work to get all the new electrical stuff nicely positioned for service. Thanks again for the great product and the excellent customer service!" BASE: 5 X 6 INCHES
Aaron Stone 4-6-2020


The fan specs are, Derale 18217, 17” High Output pusher or puller without changing anything. I only seem to hear the BUZZ when it is shutting down or when it is going slow. Before I got the AC 85 I had wired low speed with one relay to key and hi speed with another relay and a T stat so it didn’t draw much on the relays but it ran from the time I started tell I shut it down. Yours is much more precise and reliable. I will try to do a video this weekend.
Thanks again
From the desk of
Chris Mueller
