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

[workingonit]

I previously installed a 3000 cfm Flexalite fan in place of the viscous fan (which was failing). I "redneck engineered" the installation, but it's been perfect for the almost three years I've used it, so I think I'm overdue for throwing another mod at it, when I take apart my engine bay (soon), for a thorough smoke test, parts inspection & replacement, and general cleanup. I'll make the wiring for my fan look more orderly, at the same time.

While there, I'm planning to install a cheap "DC Brush Motor Speed Controller", sourced from Amazon (with good reviews), to be able to lower the fan speed when it's not necessary to run it at full rpms. Currently, it runs full beans all the time, roaring even at idle at lights, and probably totally unnecessary at highway speeds. I most notice it when I'm pulling in my driveway, and opening the swing gate...it's loud. I bought a
ICQUANZX DC Brush Motor Speed Controller DC10-55V Forward Reverse with Digital Display&Fan Inside 40A-60A https://www.amazon.com/dp/B081YYG5MG...roduct_details with 40amp continuous/60amp max capability for the 18amp Flexalite fan (my first post in bcredliner's thread on electric fans).

From what I've seen and read, this should be able to lower the fan speed when I want it, but I'd like someone with electrical/electronical experience to chime in, and tell me that I'm not going to burn out my primary fan, just as summer approaches (auxiliary fan just won't be enough, alone).

I plan on mounting the unit on a small plastic clipboard, attached to the seam where the carpeting stops, rising onto the console (driver's side). It'll be modular, with proper easy to remove connections, so if it suddenly fails, I can quickly make the fan run on the already installed wiring.

There's a three-position switch attached to the unit (forward-stop-reverse), but I'll only want it set to "forward" of course (though my fan is a "puller" by design), and I wonder if I accidently select the other positions, will the unit cause damage to the fan motor, running at full speed? Of course, the unit came with no instructions.
which is forward, which is reverse?

I'll probably mount the unit to the backside of the clipboard using Velcro strips, and also use them to attach the rear of the clipboard to the console carpet, for steadiness.
lightweight control unit assembly should be out of the way and accessible

I already have a "lockbox" mounted to the front of my seat, in a black bag, which will obscure the speed control unit from sneak thieves, I hope. But then, I hardly ever park where they might be prevalent.

[80stech]

Is there not a dedicated fan controller available ? It would be best if you could keep the controller near the fan and have it vary speed or switch speeds according to a temp sensor.

[workingonit]

Originally Posted by 80stech

Is there not a dedicated fan controller available ? It would be best if you could keep the controller near the fan and have it vary speed or switch speeds according to a temp sensor.

There are, but they are much more expensive (I'm retired, my much younger wife doesn't/won't work, trying to save a little money in a bad economy).

The Flexalite variable speed units I've seen, run from about $120 to $210. I've been seeking substitutes, from Jegs, Summit Racing, Ebay, and various electronic supply houses I used back in the day at work, but never came up with a good "fan" controller.

My thermostatic control works fine, so no need to replace it, and the Power Magic Pro BlackVue Vehicle Battery Discharge Prevention device I rigged, for letting my fan run until a set time or voltage drop, works fine, too. Why start over, replacing all, when I might be able to manually vary my fan speed for $22 + the cost of a few feet of wire, and maybe a few connectors I already have?

I'm just asking those that are knowledgeable about DC motor controllers "if the "brushed" fan motor on my Flexalite 238 fan might be harmed by this aftermarket controller"? There were videos of a guy running a couple of trolling motors using one, and another powering a Dremel or similar. I just want to get the best bang for my buck.

[workingonit]

Today:
I went outside to check on my charger/maintainers I use on all four of our vehicles not inside the garage, because there have been a couple of nearby lightning strikes (after two days of sometimes heavy rains), that caused our power to flicker. Those charger/maintainers use outdoor extension cords (14 or 16 gauge, depending on the distance from the 120vac outlet in the garage), and all run thru a 12 gauge GFCI, which trips a lot. While checking, I looked into my fan speed controller project, trying to work out details of controller placement in the interior, and also what I'll need to change and-or add to the wiring, underhood.

The controller itself will fit sideways into the unused cigarette ashtray on the console, so I won't be using a clipboard to the side of the console. I'll be mounting an extra holster there (perfectly legal in Texas, nearly a neccessity lately; the lockbox in front of the seat is for when and where I need to secure my pistol), instead. That band of carpeting is perfect for holding a heavy-weight old-school 9mm, FYI.

I'll move the small Power Magic Pro Battery Discharge Prevention device (that's currently in the ashtray) off to the side, and attach it to the dash with velcro, making room for the fan speed controller there.

I made a rough measurement of how much wire I'll need to run from the controller, under the dash, thru the firewall (I've already made an opening, when I wired the electric fan 2+ years ago, then resealed it), and to the circuit breaker (which will be the power source) and to where I'll be putting a junction block (where the controller output feeds the fan, or, as it's configured now, the speed controller output will not be connected).

I'll be using 12 gauge wire, black & red, with the input & output negative connections going to the nearest grounds I can hook them to, so only the input & output positive wire need to be as long as 8-10 feet. Since the fan, at full speed, is rated at 18 amps, and while I've not checked the current draw with a meter, the wiring has never gotten hot, despite being only 16-14-12 gauge at various spots on the way to the fan. The self-resetting 30 amp circuit breaker hasn't (and shouldn't do so) tripped yet, and the power relay (30 amp rating) never gets hot, either, so the new 12 gauge wiring should be more than adequate.

I'll get around to wiring the controller up soon (I need the new juction block first), so wish me luck. I'd really hate to fry my electric fan, but it'll most likely be fine. I've rigged-up some really sketchy circuits before, and never let the smoke out, yet.

[X5chemist]

Is the fan brushless? A brushless fan will require less amps to ramp up when needed. Plus control will be easier to fine tune.

[workingonit]

Originally Posted by X5chemist

Is the fan brushless? A brushless fan will require less amps to ramp up when needed. Plus control will be easier to fine tune.

Nope, the product description I found on the Summit Racing website shows it to be a brushed fan motor,

so the controller I bought should work fine. I'm going to set it at a lower speed for start up, and then turn the speed up in traffic, for a higher speed and more cfm's. On the highway, I'll turn it back down, though.

The controller has over twice the amp rating that my fan is supposed to draw at max, so it probably won't have a problem. I bought this unit because it

• 1) has mostly high reviews,
• 2) is compact and self-contained (after I opened the case and installed the forward-stop-reverse switch and potentiometer), easy to mount in easy reach, and
• 3) has a speed% display on it.

At $22, it's a start, and if it fails, I guess I'll have to upgrade. If, for some reason, my fan motor gets fried, I might try and modify an aftermarket "brushless" fan to fit in place of the Flexalite. All the brushless universal fans I've found (with good CFM ratings) are priced sky-high, and not a choice. But...

I think I could fit a TOPAZ 64546921381 Auxiliary Condenser Brushless Cooling Fan Assembly for BMW X5 2000-2006 into the space behind the radiator (modified to fit, flow reversed), and it could be sisterred to the factory auxiliary fan. Maybe they could both be controlled by the OEM circuitry?

Last alternative, I could always install a new viscous fan assembly for about $100-125, but I'd also want to install a Stewart water pump before that (my water pump probably wouldn't last too long with a visous fan attached). Hopefully, my fan controller will work as designed, and as I hope for all my projects "it might just work" (I've put similar stickers on my home-built trailer, which is a bit out-of the-ordinary, but works)....

[X5chemist]

Spal makes brushless fans. Can it start the fan at full voltage and ramp it down?

The TOPAZ 64546921381 is a good fan. I've been running one for three years. Since it's brushless, it takes almost 31 seconds to stop spinning from top speed. Works so good my A/C can reach 42F.

[wpoll]

Originally Posted by workingonit

... I think I could fit a TOPAZ 64546921381 Auxiliary Condenser Brushless Cooling Fan Assembly for BMW X5 2000-2006 into the space behind the radiator (modified to fit, flow reversed), and it could be sisterred to the factory auxiliary fan. Maybe they could both be controlled by the OEM circuitry? ...

Just FYI, I doubt you can run two aux fans on the OE aux fan circuitry (in the DME). The DME monitors the fan and also use PWM to control it, so having two fans attached could possibly cause a DME error (which would shut the fan(s) down).

[workingonit]

Originally Posted by X5chemist

A) Spal makes brushless fans. Can it start the fan at full voltage and ramp it down?

B) The TOPAZ 64546921381 is a good fan. I've been running one for three years. Since it's brushless, it takes almost 31 seconds to stop spinning from top speed. Works so good my A/C can reach 42F.

A) As far as I can tell, the SPAL brushless fans (comparable in size and CFM ratings) cost 3-5x what my Flexalite fan did; too much. The $22 fan speed controller came with zero instructions, so I don't know if it will start at low or high speeds, so I'm betting it will work either starting at a low setting or on the "stop/off/neutral?" setting when first switched-on (ignition on), then flipping the rocker switch to "forward" on low. I'll still have to determine what the single-bar and double-bar markings on the switch mean. I hoping the Flexalite fan motor will tolerate rotating backwards, if I have to experiment to find the correct way to toggle the rocker switch.

B) I was looking at the Topaz fan long ago, actually thinking about using it like I outlined above, but chose to go conventional with a fan by a brand I'd used before (Flexalite). Mine works so good, my A/C can reach 38F. haha

Originally Posted by wpoll

Just FYI, I doubt you can run two aux fans on the OE aux fan circuitry (in the DME). The DME monitors the fan and also use PWM to control it, so having two fans attached could possibly cause a DME error (which would shut the fan(s) down).

That was a concern I had, when I thought about using a second "auxiliary" PWM fan (see above), so I went conventional. Not knowing what sort of sensing is going on in the PWM fan-DME circuitry, I wasn't quite ready to experiment, 2.5 years ago. I would've just used the trigger wire run to both fans, with separate power and grounds for each.

I once doubled/sisterred fuel pump relays on my S-10, 25 years back, after I had the single relay fail twice, at night, out of town, at the worst times. I used the same set-up as I would've with the two aux fans, and it worked...but I've no idea if there was a PWM circuit involved. I was very experimentally-minded, back in the day.

[80stech]

You likely would have to build your own controller if you wanted use the PWM from the DME to control the fan but doable. The DME does take engine/rad outlet temp into account controlling the aux fan but I can't remember if it does so gradually or only puts the fan into high as a safety if the rad outlet gets to a certain point.