Anyone use a PWM cooling fan controller?

[ryans88gt]

considering those small fans only draw a few amps... why would you not just want it on all the time?

[jhoefer]

considering those small fans only draw a few amps... why would you not just want it on all the time?

Less noise and less fuel consumption.

[Piledriver]

considering those small fans only draw a few amps... why would you not just want it on all the time?

The 10" Maradyne fan on my ac condenser looks ~just like that.
rated at 8 or 9 Amps. Moves enough air to be actually useful..

It runs off a pressure switch, probably work OK using a simple Hobbs switch on an air-air setup.

PWM might not be worth the effort, its liable to be fully on or off in any case.

PWM is useful if you want soft start or to regulate at some temp.
You just want it to cool off as rapidly as possible in this case.

I'd try it in KISS mode first before adding complexity.

[GS guy]

Yea, the noise of a running fan just behind your head is my concern. I've heard a Corvair fan in a similar car to mine and it definitely required ear plugs while driving!

These look interesting:
http://www.futurlec.com/Relays/SSRDC100V40A.shtml
and
http://www.hella.com/microsite-electron ... y-130.html

The fan I'm intending to use is a SPAL 11" pusher. I'll need to blow "down" through my IC and I have just enough room above to fit in an 11" 944cfm model (~8A). My IC core is 10"x15". Unfortunately I can only find a straight blade model available in this size and frame, although they do make a preferable curved blade model, but nobody carries it in the US (that I can find anyway).

The SSR "power" relays are a bit expensive - anywhere between $30-$50. That's a bit to throw out just to try out an idea (although I've certainly thrown out a lot more $$$ than that on crazier ideas!). Seems like one or the other should work using a PWM output from the MS (if I can determine I actually have one available!). Main thing is I'd want to make absolutely sure this couldn't damage (or cause some other odd-ball noise issue) the MS controller.

I'll work up a simple circuit design and see what you guys think.
Jeff

[Piledriver]

A Corvair or even VW fan are not comparable to this, those are pushing 15-1700CFM at >5 inches of WC pressure, and sucking MANY HP doing it.
I ~guarantee part of the noise heard is the fanbelt screaming.

The radiator fan is a gerbil blowing through a straw by comparison, even if its rated CFM looks similar, that's with absolutely no backpressure... one of these things is not like the other... 130W is a long way from ~15-20 HP power draw.
(130W=0.174333 HP via Google)

Kinda like comparing certain EFI fuel pumps rated for flow with zero backpressure vs. a Bosch -044 that's flow spec'd at ~90 PSI...

The Maradyne I have moves a lot of air, but its not obnoxious, even with my head in the fender to check something out, even sucking through a hole in the fender a little bigger than the size/shape of a small cup of coffee on its side behind the bumper.
(sealed to fender, one way in/out)

Curved blade, and reversible. Not cheap tho. The SPAL is probably ~equivalent.
Maradyne makes a lot of different sizes...
http://www.maradynehp.com/champion-series.html
A lot of their stuff is even made in the USA.

Mine keeps my single 12x11 (effective area) parallel AC condenser sufficiently cool in Dallas, sitting still in traffic with >140F air coming off the pavement. I thought I was going to need one in both fenders....

I would put it on a temp switch and see if its actually annoying over the intake... and exhaust.. and road noise, first.

Adding complexity is OK when it is actually required, otherwise its something else to break.

[GS guy]

Yea, a Corvair fan was an extreme example of "too much noise", but it certainly left an impression! It was actually fine under 3K rpm, but above that Look Out!
I'm liking those Mardyne fans Pile! Their 11" model is exactly what I've been looking for. Definitely worth a try.

Agreed on starting out simple too. I'll be doing some manometer testing at the beginning anyway. My intercooler is inside a semi-closed engine compartment, and knew from the outset it was going to be a challenge to get decent cool air-flow through it. I'd been planning all along to seal the upper half of the IC to the engine cover and duct fresh air to it from side mounted intake ducts. Typically cars have a high pressure area underneath, just ahead of the rear tires, and I'm 99% sure my Deserter buggy will be the same. This will likely want to push air up into the engine bay - directly behind the cockpit. It could very likely want to "blow" engine warmed air up through the IC and out my intake ducts! If I had room, it would make sense to duct this high-pressure zone up to the IC, and maybe out the top. Manometer testing will tell the tale. My hope is the side ducts will be at a slightly higher pressure than the bottom of the IC, providing for at least some marginal natural air flow. Then hoping the fan will kick that flow up to a difference-making amount.

I'll have to see how noisy the fan really is in operation @ full speed.

[GS guy]

I think I found my PWM solution. I'd seen this unit before but thought it only had on-off functions (maybe it was an earlier version I'd read about?). Current model appears to have full PWM control, with low and high set points and PWM in between. Plus, it will monitor just about any type of sensor, including the GM IAT I want to use - I can just add another bung to my IC-TB tube. Not cheap, but with the Mfg. name the quality should be tops:
http://www.lingenfelter.com/mm5/merchan ... nKwIb-q9EJ

Summit has these for a little less $$. So keeping this in my back pocket as a solution to a "possible" need down the road. Still won't know what's what (and what's needed - or not) until I can get the buggy driving and do the manometer testing.
Jeff

[GS guy]

Well, that idea above is a bust. Carefully reading about the Lingenfelter unit, it specifically states it is for "brushless" fans. More digging and, at least in aftermarket automotive cooling these are not your typical generic cooling fan. Scratch that "solution".

Spent some hours yesterday digging back into my MSII build notes and recalling how I put it together. I figured out I could modify the FIdle output for PWM control, but since I'm using the stepper function for idle control - there doesn't seem to be an alternate window in Tuner Studio to get PWM operation out of the FIdle control circuit (other than idle control). Seems like an either-or situation? On/off control is available in the generic IO area, but no PWM.
I was thinking I could use the idle control functions (with some creative settings) to get the fan control I'm looking for using the idle control parameters. I read elsewhere MSII does not have a generic PWM output option? Only boost control and PWM idle?

So - it looks like the electrical side of the solution is some straightforward minor mods to the MS board and an external SSR, but the programming side won't accommodate the function.

I looked more into the IO extender boards available, but for needing just one output they're overkill and expensive. I may be down to just using the generic on-off function of the FIdle circuit.

[Piledriver]

As I said before, you aren't trying to regulate the temperature of the intercooler, so pwm is of no real benefit.

You need cool or not cool the intercooler on demand.

The only need for PWM in your case is a variable speed noise control, and the controllers for that don't exist.

You could just as easily have it on a boost controlled switch with a run-on delay.
That would actually be ~ideal...simple and cheap.

You could probably use a hobbs switch to fire off a turbo timer to run the fan.

[GS guy]

Thanks for thoughts on this Pile. Always gets me "out of the box" when I read your comments!
Still think I need a 2-stage speed control, low speed to come on at a lower temp, then full speed at a higher temp (or boost level). More research to do....

[Piledriver]

Here's a plan that provides some redundancy:
Hobbs switch (or MS if programmable output exists) activates a fixed pwm low speed with run-on timer, you could put a knob on it for speed control.
Secondary temperature sensor/relay pulls same to ground for full speed

They both pull to ground so they will not "fight" each other.

MS3/MS3X combo has more I/O including generic programmable variety that you'd know what to do with, and a couple of the outputs you can use for PWM are the existing mainboard injector outs which are good to 14A each...

...Although I would still recommend an external SSR, even a DIY one, just to keep the PWM/kickback noise out of the ECU.
A spare injector or even IGBT (ignition, with current limiting etc protection) driver would be sufficient, there's really absolutely no need for an expensive prefab SSR.

Considering what you were looking to spend, a MS3/MS3 upgrade would make economic sense, and has FAR more useful features than MS2 will ever be capable of simply due to hardware limitations.

[GS guy]

Just when I was scaling back my PWM ideas I ran across this little guy:



I might just have to pick up one of these up and play around with it. Figured if nothing else, I can use for the "low" fan stage. Or get another IAT sensor and see if I can get the two to play well together.....
Need to dig into my MS notes again and see if I can come up with a 2nd on/off output. Thinking I'll still need a 2nd high speed relay set-up - possibly totally separate from MS, but preferably integrated to act on IAT or MAP changes.

Give me something to play with over the winter! I've yet to run the thing on my engine and already modded it a couple times!
Jeff

[GS guy]

So to get the 2-stage fan cooling I'm after I'm looking at using the FIdle (on/off control) and one of the LEDs, probably ACCEL for the 2 outputs.
I've been reading up on how to reconfigure the LEDs for relay switching duties, but haven't been able to find any pics of a V3 board with LEDs converted for specifically for GPIO. The higher power circuit is straightforward and easy to configure in the (conveniently adjacent) proto area, but it's unclear if the LED circuit itself needs to be altered to re-purpose the output? Can I just tap off the adjacent resistor (for D16 ACCEL, that would be the top end of R29) and feed that into the higher power circuit on the proto area? The Megamanual indicates R29 is removed for this - but can the resistor be left in place and "piggybacked" with the new circuit (keeping the LED functional)?

Going to try one of the inexpensive PWM controllers and use for low-speed setting (if not variable speed) and SPDT relay to switch between the low and high speed settings.

[GS guy]

Well, the experiment was a partial success. I re-purposed my Stim power supply to power the PWM board, found a small 12V motor for a load and scrounged up a spare GM water temperature thermistor. PWM powers the motor just fine, and speed control via the rheostat works well. I tried a couple different configurations of integrating the temp thermistor, and best seems to be in parallel with the rheostat. This provides a bias to overall motor speed, and dipping the sensor between glasses of hot and iced water does change motor speed (in the right direction - cold to hot speeds it up).
It looks like, however, the resistance range of the thermistor is insufficient to make that much of an overall speed change over the narrow range I'm interested in, around 100F up to 140F (~950ohm change). This small change looks like it would only change the motor speed slightly and definitely not worth the effort of installing a new bung into the intake system.

I can still use it for the slow speed setting of around 50% fan output, so that part looks like a win.
Got in touch with DIY AutoTune and confirmed I can piggy-pack off an LED for one of the programmable outputs (adding an output circuit on the proto area). The other I'll use the FIdle circuit set up for general purpose I/O. I think a SPDT will work for switching between low and high speed, with a SPST relay as the main on/off control and feeding the low speed side through the PWM. I can vary the turn-on temperatures as desired (or use other control functions like boost or TPS) through MS, and low fan speed through the PWM.

[ryans88gt]

Seems like an awful lot of trouble to go to in order to get a low fan speed setting.

why not just get a fan speed controller?

http://www.haydenauto.com/Featured%20Pr ... ntent.aspx