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Hey all. I need LOTS of help working through a problem.
I'm clearly on an electrical learning curve here.
Disclaimer: Initially, the focus here is in a Porsche 928. But it's a solution I would like to apply to my XJS, sooner rather than later.
I post here because Rennlist, members there can just be brutal in ways. No fun.
The fan clutch on my 928 has failed. A new one costs about 200$, plus the time and work (which I enjoy kinda) to remove and replace the part. So, I figured (like I will on my XJS soon enough) why not go electric?
This is what I have. There is a good fit fan (with modifications) for the 928. A fan from a early 90s Volvo. Single large fan with a PWM controller built into it. Just needs a signal.
The fan relies on a wired 12+ battery voltage connection and is controlled by a single wire into the built in PWM controller that is sent from the ECU to control fan speed. The ECU gets is signal from a coolant temp sensor (easily sourced).
The advantage of the PWM set up is no power spikes at start up (a slow start) and that the fans will not be OFF/ON or 2 speeds only. Y'all know what I'm saying... The 928 already suffers (somewhat) struggling to keep up with electrical demands as is.
What I'm obviously missing here is the ECU signal. I can place a temp sensor,,, but how and where can I send it's signal to then signal the PWM controller in the fan?
Is there a product out there that doesn't cost a million?
Is this simpler than it seems?
Any guidance, clues or direct advice is suPer appreciated.
I've looked into this in the past and couldn't find an easy way to drive the factory PWM controller.
So I cheated and bought an AutoCoolGuy PWM controller. That one is good for 55 amps and he goes up in capacity and price. I have one on my XJS and my MGB and just put one on my Dad's Jeep. We're putting one on his Charger next. His controller's have full PWM capability and use a normal 1/4" or 3/8" temp sensor.
His website isn't the greatest but he makes an excellent PWM controller.
It's not want you were looking for but it's an easy way to get you to where you want to be.
I've looked into this in the past and couldn't find an easy way to drive the factory PWM controller.
So I cheated and bought an AutoCoolGuy PWM controller. That one is good for 55 amps and he goes up in capacity and price. I have one on my XJS and my MGB and just put one on my Dad's Jeep. We're putting one on his Charger next. His controller's have full PWM capability and use a normal 1/4" or 3/8" temp sensor.
His website isn't the greatest but he makes an excellent PWM controller.
It's not want you were looking for but it's an easy way to get you to where you want to be.
Hey Man, Thanks!
A big THUMBS UP to your "Looking to Come Back Into the XJS World" thread. Amazing stuff and a help to all... Jus say'n.
I've been seeing the AutoCoolGuy stuff (and yes his site is a trip)... The only (well there are 2) issues I see with the controller... One is the size. There so so little room under the 928 hood for anything extra - and the autocool product is pretty large. Also, connected to that, is the controller doesn't look water resistant or proof. Ya know, I might be able to find a place for it somewhere (and I haven't conducted a extensive search) but that place might be slightly exposed to the elements... Then, there is the cost. I'm not a cheap skate, not exactly, BUT with 4 cars all needing attention, I need to save a penny where and when I can.
The fact that YOU recommend it though says a LOT... I've seen this from JEGS which seems to be a reputable group (I've seen there name before) but dont know and haven't heard any testimony from "known" folks saying its a good thing. But, it looks like the controller might just fit into the original slot on the fan shroud itself - if not its smaller at least. Its cheaper - both are a good thing.
All I have had heard and read in researching this, is that if its POSSIBLE to stick with what, in this case, Volvo made - OE in this case is better than aftermarket productions. And I would tend to believe that. I just cant think of a way to provide a right signal to that single OE wire controller in the Volvo unit. Doggone it.
Hey all. I need LOTS of help working through a problem.
I'm clearly on an electrical learning curve here.
Disclaimer: Initially, the focus here is in a Porsche 928. But it's a solution I would like to apply to my XJS, sooner rather than later.
I post here because Rennlist, members there can just be brutal in ways. No fun.
The fan clutch on my 928 has failed. A new one costs about 200$, plus the time and work (which I enjoy kinda) to remove and replace the part. So, I figured (like I will on my XJS soon enough) why not go electric?
This is what I have. There is a good fit fan (with modifications) for the 928. A fan from a early 90s Volvo. Single large fan with a PWM controller built into it. Just needs a signal.
The fan relies on a wired 12+ battery voltage connection and is controlled by a single wire into the built in PWM controller that is sent from the ECU to control fan speed. The ECU gets is signal from a coolant temp sensor (easily sourced).
The advantage of the PWM set up is no power spikes at start up (a slow start) and that the fans will not be OFF/ON or 2 speeds only. Y'all know what I'm saying... The 928 already suffers (somewhat) struggling to keep up with electrical demands as is.
What I'm obviously missing here is the ECU signal. I can place a temp sensor,,, but how and where can I send it's signal to then signal the PWM controller in the fan?
Is there a product out there that doesn't cost a million?
Is this simpler than it seems?
Any guidance, clues or direct advice is suPer appreciated.
Skip PWM. To complex, unreliable. Been there, done that. I have two better options for you.
1, You can refill your fan clutch using fan fluid, I've done it. Worked like new. Will cost 21$ in total. The 928 fan clutch is very high quality and can be refilled many times. https://www.ebay.com/itm/131557912302
2. Ford contour dual fan setup, it fits very well on the 928. Then you use a Porsche 944 electric fan switch (1st pict below) that will screw in to the existing threaded socket in the 928 radiator. It has 3 wires and It's 2 switches in one. Using 2 relays you have the low temp part of the switch turn on fan 1 and the high side of the switch turn on fan 2. The same way Porsche did on the 944. It's a simple wiring project this way with low current draw 95% of the time. The contour fans are a modern curved blade design and move lots of air with very low current.
Simple 125$ project with OE reliability, This is the setup I use so track tested too!
Im doing the same exact setup using the Ford contour on the XJC-R using a XJS radiator and two stage XJR fan switch. Many people use a Volvo 850 fan relay becasue it's designed for exactly this and will run two fans from a two stage switch.
Last edited by icsamerica; Apr 2, 2022 at 03:41 PM.
FWIW, I’m running Spals with the autocoolguy PWM solution. This is really well designed and solid gear. It is an open construction and while he coats everything to make it weather resistant, I didn’t want to test it. Mine fit nicely into the wing where the original coolant overflow tank belongs.
Ok! More to think about.... I cancelled the order for the single fan,,, it hadn't "shipped" yet - not even a label created. It's ok, there are LOTS of fans for the s90 and contour out there. Time is on my side.
I don't mean y'all two, just speaking generally here. Yeah,,, there's just so so much contradictory info on line, in general. Can make ya craZy 😂... I don't need any help in that department...
I was thinking to just refill the fan but EVERYTHING I read, especially on Rennlist where everything is a put down or a fight, that it's hit or miss,,, nearly impossible. For now, I wouldn't mind the OE fan if it was working correctly and reliably.
I looked at the photo in link for the replacement silicone. Is that the fan clutch in HALVES? I found no info that it could be halved and filled. Just that there was a small fill port, that would sometimes leak after, where it took lots of effort to force and spin the new gel into the housing. As it is now I can stop the fan with my hand when the car is hot. It spins, but not hard core.
About the electric fans on relays. I've heard that the relay contacts would melt, that it kills alternators, that the 115 amp Porsche 928 Alt can't push it (especially at start up) and hold the voltage with lights on, AC on, brake lights etc... and an expensive $$$$ alternator upgrade would be needed...
? +++... I also don't know (it is a manual transmission) that there is a port for the switch in the radiator...? There must be as there are no trans fluid coolant lines.
The PWM Gizmo is $160 for the unit, then the fan $100, then the bits and bobs... $260 - $300.
One worry for the 5x4.5x2 coolguy unit in the Porsche is WHERE would it go without LOOONG wire runs,,, but there has to be a solution to that. I have PWM in both XKs, and I do like the way they work. I've watched many times as the fans would slowly KICK on and come to speed, then slow, start slow and speed up... Just makes sense. But, what the ECU is doing is like magic. I'm sure it's just a from 0v to 5v signal that is telling the fans what to do in relationship to what the coolant temp sensor is reading, but damn it, no way to recreate that set up in an upgrade that I can understand...
Some Help Working Through a PWM Problem
