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Radiator fan failure

Tiny
NOTTOOBAD
  • MEMBER
  • 2004 MAZDA 3
Engine Cooling problem 4 cyl Front Wheel Drive Manual

The cooling fan doesnt come on in my car at anytime, as a result when I, m idling and stuck in traffic, The engine temp. Gauge climbs and the Fan fails to come on But when im driving, the temp gauge returns to normal. The A/C works fine except when the Car idols for a period and then the air becomes warm through the A/c.
I replaced the Fan Assembly completely as I was told the problem lies in the module which is a part of the fan assembly. Well, The Fan still does not come on after being replaced.
The fuse looks fine. The check engine light doesn't come on either.
What could be the problem?
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Saturday, June 14th, 2008 AT 4:20 PM

14 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi NotTooBad,

You must be losing power somewhere there is a 40 amp fuse that runs the system can you check to see if there is power at it?

Here is a guide

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here is a wiring diagram so you can see what's going on. (below)

There is also a temperature switch that could be bad as well. Also check the grounds for the control module.

Please let us know what happens.

Cheers
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Sunday, June 15th, 2008 AT 8:37 AM
Tiny
NOTTOOBAD
  • MEMBER
  • 4 POSTS
The Fan does not operate with the A/C on either. Do you think it could be the ECT sensor or the fan relays? I recently unplugged the ECT sensor and started the car, that resulted in the check engine light coming on. I plugged the sensor back in and the check engine light remains on, Why won't it go off after plugging it back in? Did I cause another problem by doing that?
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Sunday, June 15th, 2008 AT 10:09 AM
Tiny
NOTTOOBAD
  • MEMBER
  • 4 POSTS
The Check engine light is off now, Thank God. But the fan still remains not working. Would I be able to replace the fan relay myself and if so. Where would it be located?
This is really getting me down as I already spent 500.00 in replacing the fan assembly.
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Sunday, June 15th, 2008 AT 10:31 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi NotTooBad,

The ECT sensor is not for operating the fan relays, it is for the ECU. There is another fan sensor switch.

For some cars you have to reset the ECU by disconnecting the battery terminals. Depress the brake pedals for more than 2 seconds. Reconnect the terminals and codes should be erased.

Test the fan relays to see if they are working. Did you ever check for power loss or a bad ground?
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Sunday, June 15th, 2008 AT 10:35 AM
Tiny
NOTTOOBAD
  • MEMBER
  • 4 POSTS
My fan is now working!
The mechanic who installed the new cooling fan assembly didn't plug in the connection all the way. There was a plastic tie-on strap preventing you from plugging in fully. I cut the strap off and pushed in plug tighter and Vuah LA, It works like a charm!
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Sunday, June 15th, 2008 AT 5:47 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi NotTooBad,

Cheers, you did it.

Anyway that was poor workmanship, after the fan was replaced, it should be tested to see if it works.

What if the fan was defective even though it might be new?
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Monday, June 16th, 2008 AT 7:03 AM
Tiny
VIRACH
  • MEMBER
  • 1 POST
Neither me or my mechanic could figure out the problem with electric fan failure. One think that make it worst is that sometime it works and sometimes it doesn't. When it stop working the aircond gets warm and the car get heated.
I have sent it to authorize Mazda service center and they think that nothing is wrong (as the fan still working) and reset the car ecu. After a few days driving all of a sudden the fan stop. I have to park it along side of the road to prevent engine overheating and get it tow to a garage. The next day when the mechanic turn on the engine, the electric fan works. Why? This happen so many times. Please help.
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Friday, May 22nd, 2009 AT 7:41 AM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi virach,

Since the problem is intermittent, it most probably is caused by a faulty sensor, fan control module or bad ground connections. Remove the ground wires behind both the headlights, clean and reinstall and retest if symptom goes away.

I have the schematic here for your understanding of the circuit.


https://www.2carpros.com/forum/automotive_pictures/192750_CoolingFan06Mazda3_1.jpg



When problem happens, did the Check Engine Light come on while driving?

You mentioned the Mazda SC reset the ECU, were any codes retrieved then?
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Tuesday, May 26th, 2009 AT 12:37 PM
Tiny
BUSTA BAKANG
  • MEMBER
  • 3 POSTS
  • 2004 MAZDA 3
  • 1.6L
  • 4 CYL
  • 2WD
  • AUTOMATIC
When starting the engine fan kicks in immediately without waiting for the car temperature to rise wat cpuld be the problem
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Friday, November 3rd, 2017 AT 6:01 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,724 POSTS
It could be a bad coolant temp sensor, a bad fan relay, the ECM.
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Friday, November 3rd, 2017 AT 6:01 PM (Merged)
Tiny
HELPFULTECH
  • MEMBER
  • 4 POSTS
I've worked on a few that had that bad cooling fan relays. If I remember correctly it has a low-speed and high-speed relay. What usually happens is the relays get so hot they get stuck on the on position. This can easily be checked by swapping out one relay at a time with the horn relay.
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Friday, November 3rd, 2017 AT 6:01 PM (Merged)
Tiny
BUSTA BAKANG
  • MEMBER
  • 3 POSTS
Thanks guys wil check thm and get bak to u guys
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Friday, November 3rd, 2017 AT 6:01 PM (Merged)
Tiny
BUSTA BAKANG
  • MEMBER
  • 3 POSTS
Where do I find the sensor reply wit photo if u have one
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Friday, November 3rd, 2017 AT 6:01 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
Sure the sensor is located at the rear of the right side of the cylinder head. Here is a guide to help you see what you are in for when changing the sensor out.

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Here are some diagram (below) of where the coolant sensor is.

Please let us know what happens.

Cheers, Ken
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Sunday, November 5th, 2017 AT 4:23 PM

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