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Re: Mercedes fan upgrade
[Re: gtx69]
#838230
11/02/10 02:01 AM
11/02/10 02:01 AM
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Joined: Oct 2007
Posts: 3,877
Oregon
hooziewhatsit
master
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master
Joined: Oct 2007
Posts: 3,877
Oregon
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Quote:
trinary is pretty simple.
Looked at it some more, and I think I got it figured out. 
In the attached image, the red arrow is pointing at the 'relay' in the trinary switch. In this diagram, once the pressure is high enough, it will close and send 12v to the controller.
It sounds like in your case, instead of 12v on the right side, you have it connected to ground. So, once the system pressure is high enough, it would send a ground to the controller. Then I turn the fan on to full speed after a short delay. Does that seem to match how your car is set up? I think I have a design that will work with either a high or low to indicate the AC is on.
If I can get it to turn the fan on when the sensor input is grounded, that sensor you linked should work just fine.
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: 340727dart]
#838236
11/05/10 04:34 PM
11/05/10 04:34 PM
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Joined: Jan 2004
Posts: 3,001
Coram, NY
Pool Fixer
master
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master
Joined: Jan 2004
Posts: 3,001
Coram, NY
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Quote:
Quote:
COMON YOU GUYS!! figer sumthin out out us knukel draggers can just bolt up.
 My sentiments exactly.
All this talk of PWMs, controllers, relays, etc., is way over my head.
I was told there would be no math
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Re: Mercedes fan upgrade
[Re: Pool Fixer]
#838237
11/05/10 04:54 PM
11/05/10 04:54 PM
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Joined: Oct 2007
Posts: 3,877
Oregon
hooziewhatsit
master
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master
Joined: Oct 2007
Posts: 3,877
Oregon
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Quote:
Quote:
Quote:
COMON YOU GUYS!! figer sumthin out out us knukel draggers can just bolt up.
My sentiments exactly.
All this talk of PWMs, controllers, relays, etc., is way over my head.
I was told there would be no math
No math on your end 
You'll have to hook up power, ground, the temp sensor, and the trigger wire to the fan. Turn two knobs to set the on and full speed temp, and forget it.
I on the other hand...  I get to read the two temps you selected, then figure out how to increase the PWM duty cycle linearly from one to the other. The PWM itself is handled in hardware, so I just tell it what duty cycle to generate 
But now, at least for my own personal controller, I'm thinking of giving it a temperature (ie, 200*F), and letting the fan vary speed to maintain that temp (within reason of course). 
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: hooziewhatsit]
#838239
11/05/10 05:05 PM
11/05/10 05:05 PM
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Joined: Feb 2003
Posts: 8,670
Andrewh
master
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master
Joined: Feb 2003
Posts: 8,670
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Quote:
Quote:
Quote:
Quote:
COMON YOU GUYS!! figer sumthin out out us knukel draggers can just bolt up.
My sentiments exactly.
All this talk of PWMs, controllers, relays, etc., is way over my head.
I was told there would be no math
No math on your end
You'll have to hook up power, ground, the temp sensor, and the trigger wire to the fan. Turn two knobs to set the on and full speed temp, and forget it.
I on the other hand... I get to read the two temps you selected, then figure out how to increase the PWM duty cycle linearly from one to the other. The PWM itself is handled in hardware, so I just tell it what duty cycle to generate
But now, at least for my own personal controller, I'm thinking of giving it a temperature (ie, 200*F), and letting the fan vary speed to maintain that temp (within reason of course).
do you actually have a scale on the knobs, or are you guessing?
Do not set the fan to stay on.
when moving it will actually inhibit air flow.
I can tell when I hit the freeway with the fan running, my temps are higher than if the fan is off. That is why I mentioned a speed sensor. To make sure it cuts off when moving.
I have thought of a manual switch before, but woe und to him that forgets to flip it back on when leaving the freeway after a high speed run and gets stuck in stop and go traffic.
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838240
11/05/10 05:43 PM
11/05/10 05:43 PM
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Joined: Jan 2004
Posts: 3,001
Coram, NY
Pool Fixer
master
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master
Joined: Jan 2004
Posts: 3,001
Coram, NY
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Quote:
see this is what happens when you listen to grownups talk. just wait and we will tell you when it is done.
I feel like this right now:
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838243
11/05/10 09:12 PM
11/05/10 09:12 PM
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Joined: Oct 2007
Posts: 3,877
Oregon
hooziewhatsit
master
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master
Joined: Oct 2007
Posts: 3,877
Oregon
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Quote:
do you actually have a scale on the knobs, or are you guessing?
Do not set the fan to stay on.
when moving it will actually inhibit air flow.
The knobs will have a scale, and after doing some testing on my end, should be accurate to the manufacturing differences in the temperature sensors (should be very small). Standard disclaimer: all temp gauges will be slightly different, so you may have to make some adjustments to match your gauges.
I'm a bit gun-shy about just turning the fan off when you hit highway speeds. I guess I don't want to assUme that there will be enough cooling. With a temperature sensor, the controller can turn the fan on as needed.
I'll have to think about highway speeds though. Naturally, if the fan is at 90%, and the temp goes up, you don't want to slow the fan. Unless of course the fan is the reason the temp went up, and you actually need the fan to slow down/turn off. Very counter-intuitive.
Or, I could add a button similar to the one on smoke detectors: turn the fan off and ignore the temp sensor for 5 minutes. By then it's cooled off enough the fan doesn't have to turn on. 
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: Andrewh]
#838245
11/11/10 10:38 PM
11/11/10 10:38 PM
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Joined: Oct 2007
Posts: 3,877
Oregon
hooziewhatsit
master
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master
Joined: Oct 2007
Posts: 3,877
Oregon
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annndd, test results I got the fan from feets yesterday, and after doing some massaging of my circuit today, mostly got it to work. I'm driving the fan with a 100Hz signal. The fan will only come on with a duty cycle above ~85%. 90% it comes on, 100% it comes on, etc. I get nothing from 0 to that 85%. I have a button set up to increment or decrement the PWM value. While decrementing from 100%, once I get below that 85%, I can hear the fan click off. While incrementing, again, above that 85% it comes on. So I don't think it needs a higher value PWM to 'get it moving' before going to a lower one. I have the fan running off a battery in my office, so I haven't let it spin all the way up to see if there's a noticeable difference in speed between 85% and 95%  Now I'm not sure if this fan's controller is different than the aftermarket controllers, and whether they would work with lower PWM values or not.  Feets, do you know if the mercedes ECU can control a wider range of values than that or not?
If you ever find yourself in a fair fight, your tactics suck.
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Re: Mercedes fan upgrade
[Re: hooziewhatsit]
#838246
11/12/10 06:11 PM
11/12/10 06:11 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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I honestly don't know. I tried digging around on the workshop system but didn't find anything pertinent.
We stock both the new and old style fans. There is a production date split on the two part numbers so the engine controller could have different logic or Mercedes is just being anal again.
The aftermarket fans seem to interchange. Could it be looking for something coming back from the tachometer line?
Feed that beast a 40 amp fuel supply and hit it at 90%. See if it runs for more than 30 minutes. If so, that should do the trick. We'd lose the multi speed thing until you have time to figure that out but it should cool the engines.
My fan is supposed to run at 90% with a constant supply. It cools my engine.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: Mercedes fan upgrade
[Re: feets]
#838247
11/12/10 06:44 PM
11/12/10 06:44 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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Wait...
Merciless Bends has a habit of hanging on to their existing stuff and adding to it.
The electric fans used in the 90s had resistors to control the fan speed. That varied the voltage to the motor.
Now, if the engineers left that system alone but jumped to a brushless motor, the controller would pulse variable voltage to the motor.
I have a rudimentary (at best) knowledge of electric motors. I know very little about brushless motors.
Is it possible to test the fan by running 8 volts through the PWM controller?
Andrewh says he got a lower speed with lower voltage to the trigger.
Perhaps I'm way out of bounds on this. I haven't a clue.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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