Done! Electric fan speed control...I'm not an electrician in any way, shape, or form

[workingonit]

[BimmerBreaker]

The electrically assisted thermostat has a traditional wax pellet thermostat at 103C (217F) and this is the "default" opening temperature. It will power an electric heating element to open it as low as 80C (176F) under very specific conditions, for example prolonged high engine load in high ambient temperatures with A/C blasting.



Triggering an aftermarket fan on at 80C (175F) doesn't directly lower the operating temperature of the engine. It just cools the coolant in the radiator more. Yes, when the thermostat opens you get slightly colder coolant into the engine. But this also just results in the thermostat closing again sooner resulting in no real net change in temperature compared to a stock setup.

The thermostat in almost any driving condition will still be closed at that 80C (175F) temperature. The DME will typically want to maintain closer to 90-95C (194-203F) and the TDC range of the gauge won't indicate above TDC until above 113C (235F). This means BMW considers temps up to 113C (235F) to be completely normal.

None of what you described with the thermostat operation sounds abnormal.

Originally Posted by workingonit

I certainly would've liked to have the replacement fan controlled by the DME, but I didn't want to experiment and mess it up, or have both the replacement and Auxiliary fans fail to function, due to my efforts. So, after I considered making a motor controller (mostly under my control) do the same, without damage to the Aux fan's PWM wiring, I "redneck-engineered" a simulacrum, and added to my limited electrical knowledge base at the same time.

All you would have had to do to wire in a stock style PWM fan is plug the existing PWM fan harness into the new fan. If you were installing a fan of higher amperage, you would benefit from running new, lower gauge positive and ground wires. The PWM fans only have 3 wires - power which is always on, a ground, and the PWM trigger wire. There's no need to reverse anything in a shroud, you could just use a X5 puller shroud and a 3 wire fan motor that screws into it.

Stock PWM fans are a low failure rate item. Later X5's, and pretty much every BMW that followed use a single PWM puller fan. Even some M54 models use a single PWM puller fan.

For reference many people simply remove the mechanical fan and are perfectly fine running it just like that.


I'm all for tinkering, but I'm not sure what the end goal here was. Talking about temperatures and when the fan is on and when the thermostat is open makes me think there was an end goal which I can only assume, is lowering engine temperatures. The M54 is quite happy at the temperatures it was designed for, if one succeeds in lowering the operating temperature then what happens is the DME attempts other methods to warm it up (adjusting fueling, ignition advance, etc).

Running an extra fan just ends up in a weird game of tug of war where you are overcooling the radiator while the DME and thermostat are trying to maintain a specific operating temperature.

[workingonit]

Originally Posted by BimmerBreaker

...None of what you described with the thermostat operation sounds abnormal.

I'm glad that my thermostat seems to be working OK.


All you would have had to do to wire in a stock style PWM fan is plug the existing PWM fan harness into the new fan. If you were installing a fan of higher amperage, you would benefit from running new, lower gauge positive and ground wires. The PWM fans only have 3 wires - power which is always on, a ground, and the PWM trigger wire. There's no need to reverse anything in a shroud, you could just use a X5 puller shroud and a 3 wire fan motor that screws into it.


There were questions in my mind when I replaced the deteriorating clutch fan with an aftermarket fan

• 1) could I wire a brushed fan into a PWM circuit in tandem with the auxiliary fan?
• 2) how much amperage would the circuit allow (I have no idea how much the Aux fan draws..I didn't have an amp meter at that time..., and whether the existing wiring to the aux fan could accept another 18.5 amps draw, using the new fan as well),
• 3) not knowing the capabilities and function of the DME-regulated PWM control circuit, would adding the aftermarket fan to it cause a problem?

Stock PWM fans are a low failure rate item. Later X5's, and pretty much every BMW that followed use a single PWM puller fan. Even some M54 models use a single PWM puller fan.

For reference many people simply remove the mechanical fan and are perfectly fine running it just like that.

Are you hinting that I could've just removed the clutch fan, and rely solely on the auxiliary fan? I have no information about the airflow cfm, whether or not it would be sufficient to cool my M54 in Texas heat, and I don't know how old the aux fan is...it might be original, and about to die at any time... in which case a second fan would be a lifesaver, and after 50+ years driving/racing in Texas heat, I believe that more airflow is better than less (go big or go home). I never considered getting a PWM "primary fan" from a later model, never having seen one or read much about their efficacy.



I'm all for tinkering, but I'm not sure what the end goal here was. Talking about temperatures and when the fan is on and when the thermostat is open makes me think there was an end goal which I can only assume, is lowering engine temperatures. The M54 is quite happy at the temperatures it was designed for, if one succeeds in lowering the operating temperature then what happens is the DME attempts other methods to warm it up (adjusting fueling, ignition advance, etc).

Running an extra fan just ends up in a weird game of tug of war where you are overcooling the radiator while the DME and thermostat are trying to maintain a specific operating temperature.

As I stated earlier in this thread

Originally Posted by workingonit

I forgot that the thermostat is electronically controlled (I guess I didn't look at the wiring closely enough...just assumed it ran to something else... need new glasses).

You're correct, the map controlled thermostat is something I never dealt with before, too many small & big block Chevys in my past.

I'm trying to regulate things best left to the DME, and overcomplicating things, as usual.

I'm an inveterate tinkerer from way back, and sometimes my efforts to modify (everything) aren't quite as successful as I'd wished
i.e.:

• 1) failsafe/bypass fuel pump relays,
• 2) dual ignition coils for hotter spark,
• 3) secondary alternator/dual battery isolator experiments on my V6 S-10 didn't work as planned

I was more successful on later projects (two classic resto pickups, racing Chevelle), but now that I'm dealing with my latest project, the X5, I'm now on a learning curve, dealing with more computers & modules that I've never faced before.

[BimmerBreaker]

Originally Posted by workingonit

There were questions in my mind when I replaced the deteriorating clutch fan with an aftermarket fan[/list][*]1) could I wire a brushed fan into a PWM circuit in tandem with the auxiliary fan?[*]2) how much amperage would the circuit allow (I have no idea how much the Aux fan draws..I didn't have an amp meter at that time..., and whether the existing wiring to the aux fan could accept another 18.5 amps draw, using the new fan as well),[*]3) not knowing the capabilities and function of the DME-regulated PWM control circuit, would adding the aftermarket fan to it cause a problem?[/list]

You can't run just any fan into a PWM circuit, but you could have used an aftermarket PWM specific fan.

I think the easiest route for what your goal was, would have been to retrofit a higher wattage factory BMW PWM fan - run new power and ground for the higher amperage, and run the existing PWM signal to that fan. Then if you wanted a second aux fan as backup, add a temp probe into the radiator outlet circuit (easiest way is to remove the quick-connect on the thermostat and replace with one with a temp sensor probe) and then wire that to turn the aux fan on at "oh crap" temperatures. This way, if the PWM fan failed, you'd still have airflow.

Puller fans are more efficient, all BMW's with single electric fans (which is all modern BMW's that I am aware of) use puller fans for this reason.

Originally Posted by workingonit

Are you hinting that I could've just removed the clutch fan, and rely solely on the auxiliary fan? I have no information about the airflow cfm, whether or not it would be sufficient to cool my M54 in Texas heat, and I don't know how old the aux fan is...it might be original, and about to die at any time... in which case a second fan would be a lifesaver, and after 50+ years driving/racing in Texas heat, I believe that more airflow is better than less (go big or go home). I never considered getting a PWM "primary fan" from a later model, never having seen one or read much about their efficacy.

I certainly think there is a good chance you would have been fine with just deleting the clutch fan, yes. A lot of people do this. And they do it on cars with the same engine, but in bodies with much less airflow capacity. The E53 has a comparatively huge radiator for the engine size. Z3's with M54's have radiators with about half the size, and much smaller bumper/hood openings. Airflow is very limited - but tons of M54 Z3's are fine after removing their mechanical fans in hotter and drier climates than Texas (dry air is worse than humid air regarding cooling ability).

I also think, to some extent, you are giving too much weight to what a fan needs to do. The cooling requirements from a fan are actually relatively low - fans are there for idle and low speed driving - which have the lowest cooling requirements of any operating condition. Once moving, above 30mph or so, the fan should typically be off to allow for smooth airflow through the radiator. Proper ducting to force air through the radiator (instead of around, below, or above it) is more important than fans regarding cooling ability when driving. If the puller fan is fully shrouded, and running when moving, it could actually be impeding airflow. This is a big reason factory shrouds have flaps.

[workingonit]

Originally Posted by BimmerBreaker

You can't run just any fan into a PWM circuit, but you could have used an aftermarket PWM specific fan.

I figured that would be the case, so that's why I bought a brushed fan and a brushed fan controller. As far as I could tell, when researching, a similarly-sized (16" diameter, and of greater than or equal to 2500 cfm airflow) aftermarket puller fan would've cost 2 to 3x what my Flex-A-Lite fan cost. Though I expect a PWM fan would/could last longer, I tried to address that problem with the fan speed controller.

I think the easiest route for what your goal was, would have been to retrofit a higher wattage factory BMW PWM fan - run new power and ground for the higher amperage, and run the existing PWM signal to that fan. Then if you wanted a second aux fan as backup, add a temp probe into the radiator outlet circuit (easiest way is to remove the quick-connect on the thermostat and replace with one with a temp sensor probe) and then wire that to turn the aux fan on at "oh crap" temperatures. This way, if the PWM fan failed, you'd still have airflow.


I couldn't find any info concerning a "higher wattage factory BMW PWM fan" that would work for me, to replace the primary clutch fan, while leaving the auxiliary fan in place, so I chose to go with wahat I knew, and add a brushed aftermarket fan as the new primary fan. The auxiliary PWM fan does a great job as an "auxiliary", for when the A/C is on, or for more cooling when the DME tells it to come on. I couldn't find any data on the aux fan's airflow, either, so I never considered it as sufficient as a standalone, or doubling-up with another aux fan, turned into a puller.

Puller fans are more efficient, all BMW's with single electric fans (which is all modern BMW's that I am aware of) use puller fans for this reason.


Agreed; though I have used dual pusher fans with success on my old Chevelle, on both street & strip.

I certainly think there is a good chance you would have been fine with just deleting the clutch fan, yes. A lot of people do this. And they do it on cars with the same engine, but in bodies with much less airflow capacity. The E53 has a comparatively huge radiator for the engine size. Z3's with M54's have radiators with about half the size, and much smaller bumper/hood openings. Airflow is very limited - but tons of M54 Z3's are fine after removing their mechanical fans in hotter and drier climates than Texas (dry air is worse than humid air regarding cooling ability).

I wasn't going to try just using the auxiliary fan alone; it doesn't seem nearly as powerful as even the cheap 14" fan I bought to test the fan speed controller with (and later installed as a secondary fan on my GMC pickup). And as we both agree, puller fans are more efficient.


I also think, to some extent, you are giving too much weight to what a fan needs to do. The cooling requirements from a fan are actually relatively low - fans are there for idle and low speed driving - which have the lowest cooling requirements of any operating condition. Once moving, above 30mph or so, the fan should typically be off to allow for smooth airflow through the radiator. Proper ducting to force air through the radiator (instead of around, below, or above it) is more important than fans regarding cooling ability when driving. If the puller fan is fully shrouded, and running when moving, it could actually be impeding airflow. This is a big reason factory shrouds have flaps.

I do understand my cooling requirements, for the type of driving the X5 is usually used for:

• 1) 70% idling
  • a) 50% while testing, and
  • b) 20% at stoplights (unbelievably long ones, it seems, wherever I travel)
• 2) 15% driving at the 45mph limit (on the roads I most frequently use),
• 3) 10% at speeds of 30mph and below (usually thru school zones and in retail parking lots), and
• 4) 5% at 55mph-80mph (whenever I actually get to drive on a highway).

My adaptation of the factory shroud is probably 90-95% efficient, and surely better than if I hadn't kept it in use, and reied upon the aftermarket fan housing alone (as most people do, as I have seen at drag strips and car shows). The fan speed controller was bought to enable me to regulate the puller fan operation during all phases of operation, including turning off the fan at higher driving speeds, where the fan becomes superfluous.

i must reiterate, that my X5 is a "project car", not a concours restoration effort, so I cut cost corners where I can, and use methods and parts I've used with success on other vehicles, mostly my past "projects".

I appreciate the viewpoints of everyone that adds to my threads, and I've learned much from them. As on my other threads and posts here and on many other forums I've joined over the years, I post everything that I think might be of interest to others, or I or others might learn from (both good info and bad ways to do things).

This is my favorite way to socially interact, and not to participate on 99% of the "social media": to learn and or to teach (as if anything I say might be useful).

[workingonit]

In reference to WHY I chose to add a high-powered aftermarket puller fan, as opposed to using the auxiliary PWM fan as a standalone unit, or to double-up, by piggybacking a second aux. PWM fan, in the place where the clutch fan formerly resided. Here's BimmerBreaker's viewpoint

Originally Posted by BimmerBreaker

...All you would have had to do to wire in a stock style PWM fan is plug the existing PWM fan harness into the new fan. If you were installing a fan of higher amperage, you would benefit from running new, lower gauge positive and ground wires. The PWM fans only have 3 wires - power which is always on, a ground, and the PWM trigger wire. There's no need to reverse anything in a shroud, you could just use a X5 puller shroud and a 3 wire fan motor that screws into it.

Stock PWM fans are a low failure rate item. Later X5's, and pretty much every BMW that followed use a single PWM puller fan. Even some M54 models use a single PWM puller fan.

For reference many people simply remove the mechanical fan and are perfectly fine running it just like that.


I'm all for tinkering, but I'm not sure what the end goal here was. Talking about temperatures and when the fan is on and when the thermostat is open makes me think there was an end goal which I can only assume, is lowering engine temperatures. The M54 is quite happy at the temperatures it was designed for, if one succeeds in lowering the operating temperature then what happens is the DME attempts other methods to warm it up (adjusting fueling, ignition advance, etc).

Running an extra fan just ends up in a weird game of tug of war where you are overcooling the radiator while the DME and thermostat are trying to maintain a specific operating temperature.

I just drove to my Dr's office to get a "diabetic eye exam", and when I was already a mile down the road, I saw that my A/C wasn't working, though it was last week (38F out of the vents, as usual). I was running late , so I just had to accept the 90F ambient air, and continued my drive, sans A/C.

After my appointment, in the Dr's parking lot, I turned the A/C back on, and my aftermarket fan off, to see what the auxiliary PWM fan would do. It never moved, despite me toggling the A/C on-off, and observing the coolant temperature climbing up to 203F (my t-stat opens at 190.4F, which is the normal operating temperature). At that point, I turned the aftermarket fan on, to 100% power, and the coolant temp rapidly dropped to 188F, and I drove home.

On the way home, I bought a can of R134A with stop-leak, on the off-hand chance that there's a leak in the system, but shouldn't the auxiliary fan come on? if I'm correct on this, also, shouldn't the A/C compressor "NOT" engage, if the aux fan isn't working?

I ran a quick scan for codes when I got home (I have Torque Pro running at all times...except when I plug in the Foxwell...), and there were none.

It'll be 100F+ all week here, so I'll be slow in diagnosing and/or repairing the problem; I have to work outside, in direct sun, or we get feral cats, raccoons, and opossums in the all-steel garage (not to mention free-range chickens from next-door). Is there a post/thread, with a step-by-step AWR-Fix kind of procedure, Andrew???, to help out this old guy?

AND, this is EXACTLY why I added the aftermarket fan on a separate circuit from the Aux fan, because once it failed to come on, my M54 would've been cooked. As I've stated before, I don't know if-or-not the Aux fan is the original 23 year-old unit, and I certainly wasn't going to trust the cooling system's health to it. I don't even know if a brand-new Aux fan standalone could handle texas heat?

[workingonit]

I took my Foxwell out to the X5, to run a few tests before it got too hot today for me (at 74, I've had too many heat-strokes so my body temp regulation is wacko, and I'll stay just a little too long outside). I was able to get a DME code on the Aux fan not working (with no other codes or problems with the IHKA), and ran active tests on the fan itself (no success) and the A/C compressor (it worked). Also, during the 20-second A/C compressor activation, the air from the vents got just a little cooler, so I probably won't be adding the can of refrigerant I bought yesterday.

First off, I looked at three plugs under the hood: to the A/C pressure switch, to the radiator outlet switch, and to the control box on the Aux Fan, itself. Only the plug to the fan was suspect, because it wasn't firmly "clicked" into position. I probably didn't "click" it in, when I was installing the aftermarket fan's new adjustable thermostatic switch, though the Aux Fan had been working until yesterday. I cleaned and sprayed it with the last of my can of De-Oxit, and proceeded with the tests. The Aux Fan never moved when the X5 was started, or when the A/C switch was on, or even when I turned the other fan off, and let the coolant temp rise to 215F (monitored on Torque Pro, before switching to my Foxwell).

So, now I need to test the fan itself. I've read conflicting stories: either you can apply straight 12v and ground to the fan, or you can't, because it needs a PWM signal. Would two 12v wires and a ground work, or not?

If I can power-up the fan, then which fuses (or relay?) need to be checked next? I have every size and type of fuse on hand in the X5 trunk (and like Arnold said, "detailed files", and tools), but Id like someone who's tested their own Aux Fan to chime in.

If the fan doesn't work, and everything else (fuses, relay?) are OK, then I'll get a TYC fan (seems to be a "fan" favorite. But, I won't like pulling apart the front end to install it, especially in this sort of heat.

[BimmerBreaker]

You can't manually power a PWM fan with 12v. It it doesn't work when commanded on in INPA either the fan or the trigger wire has failed. It should also run if a/c is on, or if lower temp radiator hose temp sensor is unplugged.

There is also only one fuse for the PWM fan and if it runs under any conditions the fuse is not faulty. I've actually never seen a failed fuse for a PWM fan. There is also no relay for a PWM fan.

[workingonit]

Originally Posted by BimmerBreaker

You can't manually power a PWM fan with 12v. It it doesn't work when commanded on in INPA either the fan or the trigger wire has failed. It should also run if a/c is on, or if lower temp radiator hose temp sensor is unplugged.

There is also only one fuse for the PWM fan and if it runs under any conditions the fuse is not faulty. I've actually never seen a failed fuse for a PWM fan. There is also no relay for a PWM fan.

I'm glad someone with experience responded. I was going to try the "two 12v wires and the ground" procedure I had read, but I found a post (another) from 2015,

Originally Posted by David.X5

The fan (new or old) won't spin with just positive and ground connected - the signal wire controls the speed. You would need a function generator and know what sort of pulse width modulation BMW uses to manually operate it. It is better to plug the fan in and use software to force the fan on. A generic scanner won't do it, but there are several BMW specific software tools that will.

that said not to, and you've just seconded that opinion. That thread is here https://xoutpost.com/bmw-sav-forums/...not-fan-2.html

In that thread, I confirmed my next step, testing the F61 50-Amp fuse, which I had traced via wiring diagrams, powering the fan, also referenced here

Originally Posted by upallnight

If you think the fan is bad, have the car scanned. A bad fan will show up in the DME module. You can also check the 50 amp fuse in the fuse box. If it is blown, you fan is shorting out.

If F61 tests bad, wouldn't the Light Module also throw codes (which it hasn't)? So, I guess it's time for getting the TYC fan.

P.S., the current Aux Fan looks to be the original BMW part. 23 years-old. No wonder it quit (at least most of the 23 year-old co-workers I had, just before I retired, either quit or made me want to quit). I finally did!

[80stech]

If you have power and ground to the fan and it doesn't run when activated I'd say you are at about 95% to having diagnosed the problem as a bad fan. Having a scope to check the PWM, a function generator, or a known good fan to try would get you to 100%