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Dan, ASE Certified Technician
Category: Mazda
Satisfied Customers: 1655
Experience:  Auto Technician
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Drew, I have a 2006 Mazda 6 with radiator fan problems. The

Customer Question

Hi Drew,
I have a 2006 Mazda 6 with radiator fan problems. The fan turns on erratically but when it doesn't the engine overheats quickly. Even turning on the AC won't start the fan. I already switched the fan control module and for about a week the fan worked normally and then went back to the old behavior. Thus I put in an entire new fan assembly and a new FCM. Again for 2 days the fan worked perfectly fine turning on when the AC was turned on and automatically turning off a few seconds after the engine was turned off.
The interesting thing is that when the AC is turned on and the radiator fan doesn't come on the car is idling with changing rpm sometimes making short whiny noises. As soon as the AC is turned of the rpm is stable. However, when the fan was working this didn't happen.
Any idea of what else it could be?
Submitted: 9 months ago.
Category: Mazda
Expert:  Dan replied 9 months ago.

Hello my name is***** am an ASE Master Technician and I am glad to help you out with your question.

Expert:  Dan replied 9 months ago.

You need a scan tool to diagnose this, it may be a fan relay or a wiring problem. I would also check the fuses for the fan. You could also have a ECT sensor problem which would prevent the fans from coming on.

You need a scan tool that is able to read live engine data and control the fan relay.

Expert:  Dan replied 9 months ago.

Please reply to this if you need more help and we can continue this conversation. If you are satisfied with my service, please rate at the top of the screen. Rating does not close out your question. Remember, sometimes it is difficult to completely diagnose your vehicle without being there, but I will try to give you the best answer I can. If I am not giving you 5 star service, please let me know what I missed.



Customer: replied 9 months ago.
I don't think it can be ECT sensor problem because the radiator fan should still turn on when the AC is turned on even if the ECT sensor fails, no? I checked the fuses too and they are fine.
I've put in new FCM modules (which work as fan relay in this mazda 6, correct?) three times now and every time the fan works well initially and then after 2-3 days it stops working. There must be a correlation to this?!
Expert:  Dan replied 9 months ago.

There is a tsb for this, the fan module circuit board cracks.

Expert:  Dan replied 9 months ago.

Relay is separate from the module.

Customer: replied 9 months ago.
I already replaced the fan control module. That's what the recall was on, right? A cracking FCM...
Expert:  Dan replied 9 months ago.

Yes, I can send you a wiring diagram of the fan circuit if you accept.