Mazda5 fan control module question

Hi there, I recently purchased a used 2007 Mazda 5 Touring from an area dealership. So far, I love the car, but I noticed some behavior from the cooling fan that isn't quite right. I was wondering if anyone on here might be able to help.

When we bought the car, the cooling fan would run when the engine was cold and turn off when the air conditioning was turned on. It seemed like it should be the opposite. We took it into the local Mazda dealer, and after looking at it for an hour they said the wiring was wrong and it might have damaged the fan control module (they weren't 100% certain). They wanted over $500 to replace the module, which seemed like a lot. In the meantime, they said they switched around some wiring so that the fan would run all the time (when the vehicle is on) to at least protect the engine when the AC was on. At the time, it sounded like they corrected whatever was wrong with the wiring and it just needed a new fan control module.

I saw that I could get a fan control module on Ebay for $130. That sounded a lot better than the $500. I swapped it in, but no change. That's when it occurred to me that the dealer's wiring might not have been correct and maybe I need to look into that. I realize there are some sensors (engine coolant temp, crankshaft position, throttle position) and a switch (refrigerant pressure) that affect the signal to the module that may need to be looked into as well, but given the history of the wiring, it seems like I should rule that out first.

In any case, my fan now runs continuously (when the vehicle is on) and I basically have two questions:

1. Can anyone with a similar Mazda 5 tell me what their wiring into the fan control module looks like? There's a 3-prong harness and a 2-prong harness. My understanding is the 3-prong provides power and a signal to the fan control module, and the 2-prong provides variable power to the fan motor. I've attached a photo of the harnesses connected to the module with labels of what I learned using my multimeter. Does this seem right? I looked at some wiring diagrams I found online to check it against, but it was unclear what direction they were referencing when they looked at a harness.

2. The fan blows air toward the radiator (toward the front of the vehicle). See attached photo. Is this correct? It seems like it should blow away from the radiator (away from the front of the vehicle) as to be in the same direction as the airflow while driving. It seems like the airflows would fight each other when the fan is running and I'm driving. Maybe I'm mistaken on that, though.

The biggest reason I'd like to fix this is the fan is quite loud. Not in a way that there is something mechanically wrong with the fan. It's just the motor and fan itself. It's about as loud as the cooling fans of some large work vans I've driven, and I feel bad when I'm driving near pedestrians or that I know my neighbors can hear me drive down the block.

Maybe I just need to bite the bullet and take it back in to the dealer. Just worried they're going to charge the $500 for the module, find out it's something else, and it's going to end up being $1000. Any ideas, confirmations on fan rotation direction, pictures of your wiring, etc would be much appreciated. I looked elsewhere around the forum and online and haven't found anything exactly like this, but I'd be happy to be corrected if you can point me toward something I haven't found.

Thanks in advance!

OK, I responded to your question last night with a bunch of bad information (so much so that I deleted my response) I looked at my 2006 Touring auto trans this evening for about twenty minutes and here is what I have for you. Your wiring looks kosher to me, although in the one photo you mention a splice. That splice could be part of your problem if someone has hacked into the wiring for some unknown reason. I agree with you that the fan should be a "puller" rather than a "pusher" although I'm not 100% certain which way the fan spins. If, somehow your fan has been wired wrong and is spinning backwards it would explain why it is so loud. It will be hard for you to gauge this because the temperature gauge in the dash is truly worthless, but had you noticed the engine running hot when the fan was "non-functional"? Lastly, have you run a Carfax on this vehicle?

Secondtyme,

Thanks for taking a look at your 5's wiring. That's an interesting thought that it may be louder if running backwards. I'll look into things a little more and if I can confirm that it should be running in the other direction, I'll swap the positive and negative running to the fan motor.

We hadn't noticed the engine running hot on the dash gauge before the fan was running continuously, but it had also never really been in a set of strong test conditions where it was hot, the AC was on, and in stop and go traffic.

We did look at the Carfax before purchasing. It was clean, but it does seem someone has gotten into the wiring somewhere along the way for some reason.

Thanks again, I appreciate it.

FWIW, I have noticed that my 5 doesn't run its cooling fan very often at all. I have a ScangaugeII hooked up and have seen coolant temps as high as 217 degrees before the fan audibly comes on. Of course the fan may have been running at a lower less noisy speed prior to that but still. What troubles me more in your situation is that the dealer techs thought half-assing things with the fan running 24/7 was acceptable practice. My advice is to try another dealer/shop before trusting those guys much further. Good luck and keep us updated, I'm interested to see what the real cause of your troubles is...

Thanks for the additional thoughts. How do you like the ScangaugeII?

Sorry, I didn't mean to throw the dealer under the bus. Yeah, I wish the cost was going to be lower and the certainty behind the dealer tech's troubleshooting was higher, but in this case I think the dealer tech probably did reasonably okay with what he had on hand. He needed to order the part in, so it wasn't a simple check for him. It's probably better that the fan runs continuously than to remain off when the AC is on, when the cooling might be needed the most. But, it would be nice to get this running the way it's supposed to.

If I find anything definitive out, I will keep you posted.

I have had the SGII for going on five years (and three cars YIKES) I love it to death, wouldn't drive without one. It saved my bacon again this past weekend. My battery idiot light came on and the SG told me my charging output voltage had dropped to 11.6 volts unloaded.

Just a couple updates.

So, a friend has an 07 Mazda 5 Touring and I took a look at the wiring and fan. I confirmed that my fan was spinning the wrong direction and airflow should be towards the rear of the vehicle. I also learned that my wiring on the 3-prong harness to the fan control module had been incorrect. The red wire and black wires had been reversed. This is likely the wiring the dealer switched so that the fan would run all the time, because the old symptoms returned after I made this correction.

After returning the wiring to what I think is the correct configuration, the fan began to rotate in the correct direction. The problematic behavior that returned is that the cooling fan ran when the AC was off, and the fan turned off when the AC was on.

I then changed the fan control module to the new one I had bought on Ebay. The fan behavior changed. The cooling fan still runs continuously when the AC is off (even when the engine is cold), but it now cycles on and off when the AC is on. So, an improvement, but still not quite right.

Also something that remains not quite right is the noise. When the fan runs, it runs 100% and is still noisy compared to my friend's 5, which is the exact same model except mine is MT and hers is AT. I can't see how that would be different.

I'm kind of thinking that one of the switches or sensors that affects the fan signal may be wrong. Like if the engine coolant temp sensor is giving a bad reading, the fan control module could think the engine is hot when it's cold, and may try to blast the fan 100%. Maybe this would be a nice excuse to convince my wife to let me buy the SGII. I'm still under the $500 budget so far.

So I guess the verdict is still out. Sorry I don't have anything more definitive for anyone who might be interested, but that's all I know for now.

Thanks Secondtyme for your assistance and ideas.

I'm glad i could be of some help. Its good to know I was correct about the polarity on the fan/spinning backwards thing. I would love to know if the cooling fan has some sort of VFD function (thats variable frequency drive to the uninitiated) I would strongly suggest you get the SGII, i really think it will help you sort out what the root cause is for all your issues with the fans. I have said before and will say again that the temp gauge in these cars is really good for nothing. Have you noticed coolant in the overflow bottle? If so, how much is there? I would almost like to suggest tha you source a junkyard fan module, the whole kit and kaboodle, and see what happens.

The only difference on the polarity is that I originally was going to change the polarity on the fan-side of the FCM. After looking at the other 5, it turned out it was the polarity on the PCM-side of the FCM. Glad I waited before doing that.

I have read somewhere that the fan is supposed to vary its speed, basically as with a VFD. But I've read so much on these stupid fans (some of it good, some of it ehh) that I can't remember where I read it. But the gist of it was that the fan runs faster when more things call for it (AC is on, engine is hot, etc). I believe this is supposed to be communicated through the red/white wire that connects from the PCM to the FCM. Then the FCM uses that signal to vary the current to the fan motor. At least that's how I understand it, but I could be mistaken.

I haven't noticed coolant in the overflow, but I'll keep my eye open. Do you think a junkyard FCM would be any different/better than one off Ebay? I'll probably go down the SGII route next and see what I can find out about the sensors.

I also have the scan gauge E, and noticed that the temp is normally between 186-191, but does go as high as 212 when stuck in traffic on a hot day, before the fan even decides to do anything, and then when it does come on, it's sounds little loud. Maybe that is why it does not come on often. I wish they had a 2 fan setup like my Jetta had.

I suppose a junkyard FCM and an E-bay FCM may in fact be the same thing, depending on where they are coming from. For example, I believe that LKQ does an awful lot of business on Ebay and they are really just a well organized junkyard. I was actually thinking of replacing the entire fan assembly, fan, housing, FCM, wiring, the whole damned thing, not just the FCM. Markus, I have also noticed coolant temps around 215 before the fan cycles on, but mine was barely audible inside the car with the windows up. I was kinda worried at the time that the fan wasn't 100% functional, but the coolant temps came down so I quit worrying about it.

well i understand how you would be worried about an aluminum engine getting too hot, i was never worried with my 2001 alero which would always show the correct temp on the needle (not dummy) and in heavy traffice it would go almost to red and you would be so freaked out, but would then eventually come down and you could watch it all, now they are all dummy gauges so people dont freak out, also that was a regular engine not aluminum