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chuckerants
10-18-2006, 05:24 PM
After all the talk about our cooling systems, I saw this from the same place that I bought my O2 sim. It's an adjustable Fan relay that intercepts the ECU's coolant temp sensor and trips the radiator fans at the temp that the user sets (actually it works by voltage).

http://mysite.verizon.net/vze7erz1/id1.html#fdrv

AFRC
(Adjustable Radiator Fan Relay Controller)
Can be use with any 0-5V sensor signal.

The AFRC module is intended to operate a Bosch type automotive relay by switching one side of the relay drive coil to ground, the other side of the coil connects to 12V. The relay is triggered base on a user selected voltage threshold of any 0V to 5V sensor signal. As an E-Fan relay controller our module snoops the voltage on the temperature sensor that the PCM/ECM is already using so no extra sensor is required. The temperature sensor can be the standard automotive type that decreases in resistance as temperature increases (NTC) or it can be the PTC type that increase with temperature. Please specify NTC(standard) or PTC when ordering.

The vehicle must not change its measuring sensitivity (supply impedance) over the temperature range otherwise the voltage on the sensor will jump and the module will false trigger at some settings. This excludes the GM LS1, but a new LS1 module version is coming soon.

In the standard version, the three slide switches on the front of the module set the relay turn on voltage threshold starting at 4.9V and can be adjusted down to 0.1V (in seven 0.7v steps) with a 0.1V turn off hysteresis threshold to reduce relay and fan cycling. The standard settings are (NTC,4.9V-0.1V, 0.1V hys). For custom AFRC modules please specify (NTC/PTC, User adjustble voltage range, turn off hysteresis voltage). If you are unsure of how to specify custom module setting just let us know.

The module will flash the switch setting (0-7) on the LED to confirm your settings at power up and upon waking from sleep (only if the switch settings have been changed). During normal operation the module will flash its LED every five seconds, one flash if the fan relay should be off and two flashes if the fan relay should be on. Changes in fan status (on/off) or to new switch settings only take effect at the following wakeup period, which happens every five seconds.

Features:

* Microcontroller based for reliability and accuracy
* Reverse voltage protection in the event of incorrect power connections
* Low current (5 - 8mA)
* Output wire can sink up to 0.5A
* Internal flyback diode to reduce voltage spikes
* Indicator LED to confirm operation and indicate mode
* Light weight (1.1 oz)
* Small package (2.12in. by 1.38in. by 0.58in
* 12 month warranty from date of purchase against manufacturer defects

http://mysite.verizon.net/vze7erz1/sitebuildercontent/sitebuilderpictures/afrmdwgon.jpg

chuckerants
10-18-2006, 05:25 PM
As far as I can tell by watching my Autometer coolant temp gauge, the fans trun on at around 210F and turn off aroun 190F or so.

What if we could set it to go on at 190F?

Dr Evol
10-18-2006, 06:10 PM
Interesting!

I don't have any cooling problems with my 37 Koyo, but I do live in Ohio. It doesn't get too hot here except a few weeks out of the year.

How much of an effect do the fans have on cooling a car at speed?

I can see how it might help cool the engine after an autocross run or after a track session. But other than that, I don't see the need.

Do the fans run when the car is at speed? If they do, I would think the cause would be a lack of airflow to the radiator or the radiator isn't big enough for the job.

Enlighten me.

chuckerants
10-18-2006, 06:31 PM
Interesting!

I don't have any cooling problems with my 55 Koyo, but I do live in Ohio. It doesn't get too hot here except a few weeks out of the year.

How much of an effect do the fans have on cooling a car at speed?

I can see how it might help cool the engine after an autocross run or after a track session. But other than that, I don't see the need.

Do the fans run when the car is at speed? If they do, I would think the cause would be a lack of airflow to the radiator or the radiator isn't big enough for the job.

Enlighten me.

I don't think the relay affects how the ECU controls the fans in general which do not run at speed. However, with our summer temps reaching 120F, we need all the help we can get. As for just how effective the fans are, after I did the fan mod to turn on both fans, I can see the temps going down.

With the new 180F thermostat and the fan mod, my temps stay at 195F at cruise and when they do get to 210F or so, the fans bring the temps right back down to 195.

I'll just have to see how they work next summer.

Dr Evol
10-18-2006, 08:49 PM
So I guess what you are saying is - your temps go to 210 in stop n go traffic and then the fans bring in back down to 195.

I can see that in your climate. We just don't get that here in Ohio, thank goodness!

chuckerants
10-18-2006, 09:07 PM
So I guess what you are saying is - your temps go to 210 in stop n go traffic and then the fans bring in back down to 195.

I can see that in your climate. We just don't get that here in Ohio, thank goodness!

That's how it works from the factory. However, in my first summer in Phoenix, the heat is just too much for the ONE fan that truns on to bring the temp back down to 195F. So, I did the fan mod that turns on BOTH fans when the ECU sees the temp at 210F. NOW I see the temps coming back down.

With the adjustable fan relay, I could control temp that both fans turn on so I could keep the temps even cooler.

Tom @ Fast Forward
10-19-2006, 09:10 AM
Hey Chip,

Didn't know you had the 55mm Koyo. What are your opinions? Haven't been able to beat on my 99 yet with it. Maybe thet is why you have no problems with heat?

Dr Evol
10-19-2006, 01:09 PM
Opps, I have the 37 Koyo. I changed my post.