a/c coolant fan not shutting off

theblooms said:

Oof. That sucks. They are controlled by the PCM, so something is definitely out of whack.

Click to expand...

theblooms said:

Oof. That sucks. They are controlled by the PCM, so something is definitely out of whack.

Click to expand...

Mazda444 said:

Hello, I had the exact same problem with mine (fixed it last week) the problem started 3 months ago, I noticed that the fan would stay on after switch off. This had never happened before!!!!
I hope this helps:

Info I found:

Mazda 3 fan Shouldn't come on below 208F
30% at 212F
70% at 223F
100% at 230F

The Mazda 3 had no fan relay in either fuse box, all is in the electronics in the Fan Control Module attached to the fan
The fan unit (whole thing) is not difficult to take out
FCMs on older Mazda 3s can be a common problem

What I tried:

First I checked the temperatures mentioned above using a scanner (all was fine) so the ECT sensor, the thermostat were fine.
No coolant leak
Water pump had been changed recently

Turned the engine off (fan was running) used a wooden stick to carefully & lightly tap the fan control module and to my surprise it turned the fan off!!!! Tapped it again & it came back on !! so obviously it had a short.

I took the whole fan assembly off & I found a short from the ground wire on the FCM to the fan body and added a wire to make the ground & that was it.

All is working perfectly.

Click to expand...

tk1251k said:

Thanks some very helpful information I will check into that. So you took the whole fan assembly off it sounds like. It looks like a booger to get to the module. I will try what you did and also chase that ground wire down. Mine is a 2011. I may check back with you thanks.

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Mazda444 said:

No problem, I think your first step should be to turn the car off, based on the problem the fan should be running, tap the Fan Control Module with a stick from the top of the engine slightly to the right of the engine bay, if that works then you can think about taking the cooling fan assembly out (disconnect the plastic shield underneath, disconnect FCM main plug & gound wire, then from the bottom of the engine, push in 2 tabs & lift up slightly then pull down) I did it in about 15 mins

Click to expand...

Mazda444 said:

Hello, I had the exact same problem with mine (fixed it last week) the problem started 3 months ago, I noticed that the fan would stay on after switch off. This had never happened before!!!!
I hope this helps:

Info I found:

Mazda 3 fan Shouldn't come on below 208F
30% at 212F
70% at 223F
100% at 230F

The Mazda 3 had no fan relay in either fuse box, all is in the electronics in the Fan Control Module attached to the fan
The fan unit (whole thing) is not difficult to take out
FCMs on older Mazda 3s can be a common problem

What I tried:

First I checked the temperatures mentioned above using a scanner (all was fine) so the ECT sensor, the thermostat were fine.
No coolant leak
Water pump had been changed recently

Turned the engine off (fan was running) used a wooden stick to carefully & lightly tap the fan control module and to my surprise it turned the fan off!!!! Tapped it again & it came back on !! so obviously it had a short.

I took the whole fan assembly off & I found a short from the ground wire on the FCM to the fan body and added a wire to make the ground & that was it.

All is working perfectly.

Click to expand...