fan runs on and on and on and on and......

vooman · Post by **vooman** » 13 Sep 2011, 13:27

Unplugging the purple CEM wire does not stop the fan from running - so it sound like I'll be replacing the fan assembly.

Thank you draser for that tip, I really appreciate you taking the time to share your knowledge.

Ebay has it listed for around $125. Anyone know of a place I Southern CA that might have it near that price?

draser · Post by **draser** » 13 Sep 2011, 14:37

The fan module has 2 wires going to the fan, and 3 wires for input (purple and 2 more). For the heck of it, and future ref, if you ohm-meter between ground out and ground in you should see close to 0 ohms, on lowest meter scale. If you measure the other (hot) output wire and the other input (not the purple) you should see a very low resistance or 0 as well - for the module to be bad. And if you reverse the leads it would read the same. I would think the module has a solid state device for driver (transistor, etc), not a relay - not sure though.

vooman · Post by **vooman** » 15 Sep 2011, 00:17

Took out the fan unit today, and it is the culprit, so I need to decide how to get the beast back on the road.

A replacement unit runs about $200. But then it looks like this device, for $27, might do the trick also. It has a temp probe and relay that one hooks inline with the power source, when the temp reaches a variable limit, it cuts the power. Seems simple enough, but it's clearly not the original design. But then again this car has probably less than 6 months left under my ownership.

Your thoughts?

Post by **fazool** » 15 Sep 2011, 14:06

I have two S60's and am a bit of a original-oem-stock-o-phile. That said, however, there is really no compelling reason to overpay for a stock cooling fan system. Its like using salvage/junkyard parts:

If I have a brand new car which needs a new part, I want a brand new part on it.

If I have a ten year old car, I am not particularly compelled to pay $800 for a brand new part meant for a brand new car when I can get one from the junkyard for $80.

My point is sometimes its gilding a lily to buy a brand new OEM fan/part and put it in a 10 year old car because now what you have is a ten year old car with a brand new fan.

Go for an aftermarket mod. I would buy an electric cooling fan and rig it up in your car.

(hmmm....usually I am more articulate than that.....hopefully it made some semblence of sense)

vooman · Post by **vooman** » 29 Sep 2011, 00:51

So, here’s where I’m at…

I didn’t have the time to find a new fan, so I would drive and then shut down the Volvo, open the hood, and unplug the power connector to the fan so as not to drain the battery as the fan wouldn’t turn off. Then I’d open the hood and reconnect it each time I needed to drive.

The first time I did that the water temp gauge didn’t register at all. After stopping and having lunch I took off, but this time right away the temp gauge pegged at the high end, 700f or whatever it is, even though I knew the engine was pretty cooled off. Subsequently the gauge would either peg high, or look like it was registering the correct temp. There didn’t seem to be any rhyme or reason, no pattern I could see to predict whether it would on the mark or off the scale.

A few days ago all was well until I smelled that distinctive, sweet, antifreeze odor. I pulled over and sure enough the fan wasn’t turning and the water reservoir was empty. When I had plugged it together earlier I didn’t fully engine the plug & jack and during the dire the two worked loose. I filled the overflow tank - it took a shockingly large amount of water, so I’m afraid it was near bone dry. But it runs fine, no lack of power, the coolant level is stable, and I don’t see any water on the dipstick, so hopefully I dodged the bullet.

I found a salvage yard that had a fan & controller for $125 and I went ahead and got. Swapped it out with the old one and fired up the S60. Seemed to run fine, but when I shut down the new fan just ran & ran. And if I disconnected the purple control wire it would till run. That’s the same problem I have with the original fan/control mod. Unfortunately I did not test the replacement unit before I installed it, so I didn’t know whether or not it would have run with just the power hooked up and the purple wire from the CEM disconnected.

Unless I’m missing something, the fan control module is broken. Even though the fan/control mod receives power through the 2 wires, when the purple control wire is disconnected the fan should not turn. Is that 100% certain?

The salvage yard was nice enough to swap out the first salvage fan/mod for another set, which I haven’t touched yet, and I’m a bit afraid to test it.

My concern is that maybe either the power/current going to the fan through the two wires, or the power going to the fan control module (purple wire) may be too high – and that may be killing the fan control module. If that’s the case then I need to look elsewhere for the problem.

Or it’s possible that I was just unlucky with replacement fan/controller #1 was already fried when I got it.

My plan is to hook the new fan/mod into power jack but not hook up the purple wire, if I do that then fan should not turn – correct? But before I do that could someone confirm that if I run VOM leads to the two wires I should get a 12v reading – is that right?

And does anyone know what the purple wire from the CEM should read when the engine is cool; and what it should be when the system is hot and the fan should be turning?

I really don’t want to fry fan/control mod #2, I doubt the salvage yard will allow me another swap if I kill this one.
Hope that makes sense, and thanks for your help! I miss the days when everything had just +12v and ground.

Thanks!

draser · Post by **draser** » 29 Sep 2011, 07:04

Just like you said - I'd just plug in power and see if it runs. Due to lack of info from Volvo, we're just guessing here. Somebody said perhaps the purple wire is just feedback into CEM to tell when fan runs or not. It's possible from what you're saying. To get a better of what's going on in there some troubleshooting is required. You'd need to voltmeter the purple wire and see if there's a difference cold/hot. If no diff is found either your CEM is bad or purple is indeed feedback. If that were true, that means the power switching takes place in CEM. One way to tell is to ohm-meter fan module power wires, you should read continuity on both (since we assumed switching takes place in CEM). But that, IMO, is a pretty akward way to control the fan. If you still have the old fan, I'd try to ground the pin on the fan module (leave purple wire from CEM disconnected), to see if fan stops. If not I'd put 12V on it to see if it stops.

simonbyard · Post by **simonbyard** » 29 Sep 2011, 08:34

had a problem with my fan running on and on, and checking here found it was a regular problem and 80% of the time the controller was fried, and others the coolant temp sensor. However, in all my searching it seemed clear that if there is nothing wrong with the fan and controller, it will not run with just the power plugged in, as that is a constant live feed. It needs a signal from the purple wire. Hope this helps, but it is a pain, as there seems to be no easy way to test the fan without plugging it into the car - at least if there was a way to do that, it would illiminate one more thing from the troubleshooting list! And yes, I agree - bring back the old days! Why have two ECM's to control the frikkin wipers! the clock needs one ECM, three relays and fourteen wires!!!!! (ok, exagerating, but you all know what I mean)

volvodoc · Post by **volvodoc** » 29 Sep 2011, 08:54

have a dealer run your vin# many of these fans were recalled for this problem also the most common problem was the fan control module failing its worth a phone call

fan runs on and on and on and on and......

Re: fan runs on and on and on and on and......