feature request, pwm fan control

ashford · Post by **ashford** » Sun Jul 12, 2015 6:33 am

i don't know if there is enough hardware out in the wild yet for this to be an everyday thing but my fan died on my capri yesterday. scrounging around my fan collection i found a fan that fits nicely. it is from a 2008 crown vic police car, it has an intergral pwm controller built into the fan. http://www.rockauto.com/catalog/moreinf ... 497&jpid=7

i know this can be done easily with a generic pwm output but add in ac and connecting the 2 don't work.

my thoughts on this are a simple curve, start of fan on clt195= 25% to clt220=100%. then a setting for if ac on, min fan duty = 50%

arran · Post by **arran** » Thu Jul 16, 2015 3:07 am

I asked about a similar thing a few months ago. I am interested in a soft start:
http://www.msextra.com/forums/viewtopic ... 25&t=58122

brianj5600 · Post by **brianj5600** » Fri Sep 11, 2015 6:57 am

It would be nice to be able to pwm the fan in the fan control set up. I will probably just use a generic pwm output, but would be nice to be able to have it turn off or slow down with VSS. It does not appear that the tables in generic pwm allows changing the "X" axis away from rpm. It would be nice if all the features in "fan control" worked with pwm.

Jamie V · Post by **Jamie V** » Tue Jan 21, 2020 3:17 pm

I’m new to this but I can’t believe you’ve been asking for this for 5 years and it’s still not possible.

Why can’t a PWM feature (and a soft start only) be added to the fan control section?

Matt Cramer · Post by **Matt Cramer** » Wed Jan 22, 2020 11:19 am

Easy way to do this is to use a generic PWM output that increases duty cycle with duty coolant temperature.

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 2:22 pm

If I use the generic PWM then I loose my ability to turn the fan on when the AC is on along with turning the fan off when the TPS and/or MPH are above a certain point.

dontz125 · Post by **dontz125** » Wed Jan 22, 2020 2:42 pm

Use two of the unpopulated outputs for the fan output and the PWM output; say, PK1 and PK3. You would then have the actual fan signal as a prog out coming on when [Portk] [AND} '10' Hyst '10'

The fan function turns on Port K bit 1 (=2) and the PWM function turns on Port K bit 3 (=8). If both bits are on (2+8=10), the output pin turns on and drives the fan controller.

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 2:44 pm

I was reading a post you made about this last night but this sounds like Chinese to me.

dontz125 · Post by **dontz125** » Wed Jan 22, 2020 2:57 pm

Ni hau!

Heh - open up TS, and work your way through it. Set the fan function output to PK1 (aallll the way at the bottom); set the generic PWM A output to PK3. In the Programmable Outputs1 menu, select whichever output pin you have in mind (say, VVT); enable it, then set the "Active Conditions" fields. Instead of [RPM] {>} "0" "0", enter in [portk] [And] "10" "10". Select 'No Additional Conditions'. You're done!

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 3:11 pm

Ok, that’s a little more understandable.... LOL

Couple questions.

How do I adjust the Fan on Temperature & Fan off Temperature in fan control if I’m using the Generic PWM to now control at what temperature the fan comes on and off?

When the fan is told to come on (in fan control) because the AC is on will it come on if the ECT is not calling for the Fan to come on in the Generic PWM?

When the Fan is told to come on (in fan control) because the AC is on will it be a “switched” on or a PWM on?

dontz125 · Post by **dontz125** » Wed Jan 22, 2020 3:19 pm

The 'Fan ON' and 'Fan OFF' functions under Fan Control are going to have to be set so the fan is always on within the envelope controlled by the PWM signal, but off otherwise. This way, you aren't wasting PWM cells down around -40F ensuring the fan is off.

Both the Fan Control and PWM have to be 'on' for the fan control signal to operate. An AC fan signal will operate at the PWM rate, not 100%.

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 3:31 pm

So if the PWM is calling for 10% fan speed at 180° and the AC is on it will only give 10% fan speed?

If the PWM is not calling for any fan speed at 150° and you turn the AC on the fan won’t come on until the ECT reaches a temperature that calls for the fan to come on?

Basically both criteria have to be met and the AC only makes the criteria and the PWM table determines fan speed?

dontz125 · Post by **dontz125** » Wed Jan 22, 2020 3:34 pm

Pretty much.

What you can do if you don't normally want the fan on below 150F, but you DO want it on if the AC is on, is set the PWM to (say) 50% below 150F, with the Fan OFF set to 150. The AC ON overrides the Fan OFF, and the fan comes on at 50%.

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 3:37 pm

Could you add a 2nd Generic PWM table to the formula with a “this” and “that” or “that”

dontz125 · Post by **dontz125** » Wed Jan 22, 2020 3:45 pm

Hmmm ... I suppose you could. The two PWM signals would have to be in phase, or else strange things might happen.

Instead of "No Additional Conditions", set that to [OR}. Set PWM B to use PK7 (=128); the bits in use would be bit 1 and bit 7 (2+128=130). The second operating condition would then be [portk] [And] "130" "130".

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 4:20 pm

When you say “in phase” do you mean the same HTZ?

dontz125 · Post by **dontz125** » Wed Jan 22, 2020 4:23 pm

They'd have to be at the same frequency and in phase - both starting at the same time. If both were at 50% or more but offset, the effective duty cycle could be 100%

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 4:40 pm

I’m still trying to grasp all this.

So there wouldn’t be a way (even with 2 PWM tables) to have it come on at 100% when the AC turns on or ramp up to 100% if it was already on at a lower % due to ECT?

dontz125 · Post by **dontz125** » Wed Jan 22, 2020 5:20 pm

I'm describing a workaround. There currently is no dedicated function that will PWM a fan while maintaining all other aspects of the Fan Control tab.

Jamie V · Post by **Jamie V** » Wed Jan 22, 2020 7:05 pm

dontz125 wrote:I'm describing a workaround. There currently is no dedicated function that will PWM a fan while maintaining all other aspects of the Fan Control tab.

I understand that and am appreciative.

What would have to happen to get PWM added to the normal fan controls?

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