124 electric fan - Page 2 - PeachParts Mercedes-Benz Forum

duxthe1 · #16 07-23-2019, 09:56 PM

Hey thanks!

I was correct about improved A/C performance. 91F ambient this evening, watching the values in stop and go, the refrigerant temp never went over 135F and would drop by 20-30 degrees F in good airflow. When liquid R12 refrigerant hits the evaporator at those kinds of temps, that damned thing gets COLD! My evening commute is about 5 miles and with a stretch of stop and go, about 15 minutes. At full speed fan, with only two vents blowing towards me, by the time I got home I was seriously uncomfortably cold. Maximum noted engine temp 93C.

I have moved the ambient temp sensor to the top 1/3rd of the condenser in the middle and the heat soaking is better but I do notice when stationary that it gets artificially heated up a lot faster as the fan speed ramps up to the higher speeds. I can only presume that at high fan speeds there is significant hot air making its way back in front of the condenser. It's not enough to be a big deal but after the work I've put into it, I want to optimize its performance. I do think that one of the biggest problems I have in this regard is that the front of the engine is a significant obstruction to the airflow though the fan. Its hard to judge to what extent with the hood open observing but I'm eventually going to see what I can do to optimize airflow through the engine bay.
I feel that the abysmal lifespan of these inline 6cyl head gaskets is largely in part due to the marginal cooling these engines receive in stock form and anything we do to improve it will increase their longevity.

duxthe1 · #17 07-24-2019, 07:44 PM

Here's a sample of my current A/C performance...

First pic is ambient outside temp on the drive home today.

Second pic is the temp measured at the center vent, high speed fan, recirc off after less than 2 miles at speed.

Brrrrr

SpartanV · #18 07-26-2019, 04:17 AM

Re-read this thread for better understanding. I have a few questions, also regarding your overall setup.

How does the Arduino module receive vehicle speed, does that come from the PCS TCM? And how do you send vehicle speed to the transmission controller? Are you still using CIS on your m104.980?

I'd very much like to invest in this electric fan setup and deleting the aux fans would be amazing as well. I would like to go EFI eventually and maybe even swap the 722.3 in my 1990 c124 for a TCM controlled 722.6, if I cannot find a manual trans (reverse is going out on my coupe, though a fluid flush has helped for now). My r12 AC system still works, albeit it doesn't work well when it's too hot. So I need to sort that out.

Your thread is giving me ideas and inspiration to ditch the clutch fan on the coupe and pickup a w203 fan. For now I could keep the 722.3 and perhaps use Arduino with some inputs to control the fan? Hell my w201 would surely benefit from an electric fan also.

(edit) I guess I could run a fan relay controller until I go EFI... humph, but your way is way cooler and more controllable

duxthe1 · #19 07-26-2019, 10:01 PM

The Arduino gets vehicle speed over CAN from the PCS, as well as engine temp, rpm and throttle position. The PCS TCU reads a 4 pulse tone wheel that sits behind the trans output yoke and once you tell it your final drive ratio, it knows vehicle speed. It also sends an output to the speedo which you can configure for pulses per mile to calibrate your speedo. Swapping out diffs was piece of cake only needing to change the final drive ratio setting in the PCS. Its not cheap but the PCS is a badass piece of gear.

The 203 fan doesn't come close to fitting the 124, but if you're handy its not too hard to build it into a 124 shroud. If you get a junkyard fan be sure to snag as much of the connector and wiring as you can with it.

You can build a fan controller without as many inputs as I'm using and still have it do a great job. Engine temp, refrigerant temp, and ambient temp alone would suffice. I only use RPM to cut the fan during cranking but a dedicated input could do the same. Vehicle speed would be a bit tricky but not impossible to read with an Arduino. Tap the output from the speedo to the cruise amp and measure the time between pulses. Throttle position is trickier still but not a necessity at all.

Lots of possibilities....

Roncallo · #20 07-27-2019, 09:56 AM

Nice job. I may be following something like this when I install my AC system.

Roncallo · #21 08-24-2021, 11:07 PM

As fate would have it I did find I need more fan and the 203 fan is about the most powerful fan that I can presently get my hands on that has a hope in hell of fitting. SpartanV mentioned a Volvo fan. Is that fan thinner than a 203 fan. If so what model Volvo is it installed in and whats its power draw.

Samson will run hot like 110°C up to 95°F all day around town with the AC on. but I could not make it up Mt Mitchel on a 90°F sea level day with AC on. Not good enough.

The 203 fan I harvested from a 320CLK is 3 7/16" tall. I can drop the depth to 3 and 1/16" by putting a 3/8" spacer in back of the motor and milling down the front side of the motor mount. That will unfortunately place the motor to withing 1/16" of the radiator core. I will need to test that that it will not be sucked down into the core when the fan is pulling full power. The current fan I have is a flexalite low boy its 3 3/16" thick but only gives me 5/16" clearance between the crank pulley and the fan motor. It hasn't hit to date, but that's with new subframe mounts and engine mounts. So an increase in clearance even 1/8" is desirable.

The challenge is that the flex alight fan as a 4" diameter motor which has been strategically placed clear of the idler pulley on the water pump of the M120 engine. The 203 fan has a 7" diameter hub and its blades remain at the same depth as the hub up to a diameter of ~ 12". So the hub is not modifiable but in order to get this fan on I will need to trim the trailing edges of the blades by possibly 1/2".

I haven't programmed an Arduino but it shouldn't be beyond my capabilities. But it will be a learning experience. My main concern with the Arduino is can I make it automotive environmentally hardened. In any case it will be a good prototype.

One of the things I would like to ask if anyone could recommend an Arduino starter kit.There seem to be plenty of choices on Amazon from $16 to $120

Roncallo · #22 08-29-2021, 12:30 AM

I found that there are two versions of the 600W 203 fan assembly, A203 500 02 93 and a later version A203 500 16 93.

The 02 version would allow me to space the motor back and leave the shroud at the full depth. With the 16 version the motor cannot be spaced back and therefore the shroud needs its perimeter cut down. Since cutting down the perimeter will work on both fans, I am going to start the project using the 16 version with the shroud perimeter cut down. I was a little reluctant to cut down the perimeter because clamping it to the milling machine for that operation is a bit scary. But today I was successful.

The later 16 model also has the control module built into the motor so it becomes one less thing to deal with.

Roncallo · #23 08-29-2021, 12:49 AM

Machining the shroud perimeter. Only the top and bottom edges need to be machined down as the sides will be cut off to fit within the confines of the side tanks of the radiator. There are still some webs sticking up slightly that I will need to machine down even with the plane of the upper and lower edges.

Tomorrow, I hope to complete the trimming of the shroud. Then I will have to make a hub to support the fan onto a rotary table to machine the back side of the blades.

I ordered an Arduino kit but just got a refund back so I guess I will need to find another supplier

Roncallo · #24 08-30-2021, 10:59 PM

Change of plan today. After machining the plastic I realized there was enough of a planar area on the back side of the shroud that I could easily fabricate an aluminum shroud to pick up on. The Aluminum shroud is fairly simple and allows for unlimited ways to mount. It also lets me custom size the shroud for a perfect fit.

My Arduino kit also arrived today. I don't know what happened with that. They sent me a refund for it yesterday but I got the kit today.

Roncallo · #25 09-01-2021, 07:07 PM

After deciding to use an aluminum shroud over the plastic, I had to figure out a way of removing the plastic ribs that were in the way. I turns out to be really easy. Just twist them off with a pliers then go over whats left with a dermal and a file. the whole job took about 1/2 hr.

That leaves me with a planar area marked in yellow that I can pop rivet an aluminum shroud to. I will probably do a combination of pop riveting and bonding since the area is somewhat small. It may not be perfectly planer but defiantly close enough for minimal shimming. So I guess now its time to cut the shroud. It's too long to fit as is so it will be cut where my fingers are pointing in the picture with the shroud on a 107 radiator. I'm thinking of clamping this down and probably sawzalling it.

Roncallo · #26 09-02-2021, 11:25 PM

two quick cuts on a table saw did the trick.

Roncallo · #27 09-03-2021, 09:30 PM

Spent the day reading about Arduino. I got a light to blink on and off and then turn on with a photo electric sensor. A long way to go. But I can always recruit people who know this stuff.

https://youtu.be/DAn4UguyzfE

In any case I am starting to get close to the point where I will need to take the car out of service to see if this thing will fit. But with nice top down driving weather I want to put that off until the end of the season. Took the wife out yesterday for a nice drive and nothing but cool top down weather on the horizon. So I have only a few more things I can do before I am ready to proceed. For one I need to modify the thermostat housing to reroute my upper hose. Still waiting for a used one I purchased to come in from Ebay. Then I need to make that fan blade holder that is still sitting in my lathe. I wont know how much to mill the blades down until I get it mounted in the car. I also need to do some testing to see how much the fan sucks itself into the radiator at full speed. I would like to leave 1/8" clearance but that may not be enough for the stiffness required to keep the fan from pulling itself into the radiator. It may be that I will need to make the back panel of the shroud out of honeycomb aluminum.

So for the next few weeks I will be doing those last details and then playing with Arduino.

duxthe1 · #28 09-04-2021, 04:04 PM

One thing to keep in mind that I dont think I'd mentioned before.... The control signal gave me a bit of grief until I got it sorted. You should build your control circuit so that the control signal rests at 3.5V and using the Arduino pull that 3.5V to ground to create the pulsewidth. I had originally tried resting at 0V pulling up to 3.5V and it didn't work properly.

Roncallo · #29 09-04-2021, 07:50 PM

Quote:

Originally Posted by duxthe1

One thing to keep in mind that I dont think I'd mentioned before.... The control signal gave me a bit of grief until I got it sorted. You should build your control circuit so that the control signal rests at 3.5V and using the Arduino pull that 3.5V to ground to create the pulsewidth. I had originally tried resting at 0V pulling up to 3.5V and it didn't work properly.

Good to know Thanks. I do have another question for you. You say PWM at 10Hz. 3.5V but I have seen several references saying PWM at 12V.

I see you are using the earlier style A203 500 02 93 successfully at 3.5V. I'm wondering if anything over 3V is all that's required.

Here's a guy using 12V on the earlier version.

https://youtu.be/5LQMDRCO5nk

I also found another guy running his at 50Hz.

My Arduino RobRed has switchable IO 3.3V or 5V. So I'm hoping to run on 3.3V.

Roncallo · #30 09-04-2021, 08:45 PM

Kind of a disappointing day today. Just trying to get the fan to run at all. My conclusion is its dead. I might have killed it myself or maybe it was dead to begin with as it was pulled out of a dead junkyard car.

I tried it with both a 30 amp bench power supply and then a car battery.

Fortunately that is my spare. old style unit.

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