[SOLVED] Radiator/Cooling Fan Intermittent/Not Working

Brado

Brado

Problem Encounterer
Greenie N00B Member
Greenie Member
Year/Make/Model: 2008 Mazdaspeed3
Mileage: 160K chassis / <1K motor
Location: AZ
Concern: Radiator fan not turning on most times.
DTC's: None
Modifications: BNR S3v4, catless downpipe, CS internals, 3in intake, FMIC, etc
ECU/Tuning Software: Accessport V3
Tuner: DramaTuned
Is the concern intermittent? Yes
Can you duplicate the concern? Yes
Recent Repairs: Nothing fan related
Correction: N/A

Another day, another issue! This one could be an issue I've been dealing with for years now that I really think about it. It's 70-80 degrees F here and lately I've been seeing my coolant temps exceed 219 when not moving. This is typical in the middle of summer here, but not toward the end of winter.

I'd park the car and pop the hood and the fan would not be running most times. One time I actually saw it kick on and turn off again moments later, with the temps still at 228. I knew something was going on with the system, but the fan itself spins fine and freely.

So I got to troubleshooting:
  • B+ power to the fan connector
  • Ground is solid to the fan connector
  • Continuity between signal wire in fan connector and PCM connector
  • Manually applying B+ voltage to the wires at the fan, after the module, turns the fan on full tilt no issues.
Since everything going to the connector is solid, and the fan is operational, I'm thinking it's the fan module itself, but I'm curious to everyone's thoughts.
 
What happens if you sit still with the engine running? Does the fan ever kick on and stay on or does the temperature keep climbing
 
Unfortunately not. That’s how I noticed it wasn’t working because I parked when it was already hot and the fan wasn’t on. It did kick on for a second and then back off once, but most times it simply doesn’t turn on when it should.
 
I’ve ordered a used OEM Speed3 fan assembly that has everything but the shroud. I will be swapping over those parts into mine. Shouldn’t be too difficult.
 
Updating this to say that my issue is resolved. Replacing the radiator fan, with the module, is what fixed it.

I think this issue is entirely within the module. I plugged the new fan in and it ran nonstop with the AC on, whereas plugging in my old fan would turn it on for only a few seconds. Took me an hour or so to get the replacement fan into the existing shroud. Easy enough job!
 
I’m in a very similar boat as you were. I have an 09 Mazdaspeed3 with 154k miles, just over 2k on the new engine I installed.

The other day, it was 90 out and I was in the inn n out drive thru, car started getting hotter. I knew the fan turns on around 217ish, so I ignored it as it climbed up a bit. Soon it was too hot for comfort in 230s, and I turned off the car to keep it from heating up more. Later on, I got home and checked the fan for power. Hooked it up to direct power bam it worked. I also noticed I was low on coolant, so I assumed that it had just not had enough to trip the temp sensor in the engine to engage the fan. Fast forward nearly a month, which was today. Did some slow traffic driving, and the car got hot again this time, I hopped out and checked coolant. It had coolant.

When I turn on my ac, the fan goes on for a handful of seconds, then off for a handful. This repeats indefinitely as far as I know. When I got the car up to fan engagement temp, it would do the same thing. On, then off, over and over. This was at the lowest speed too, so it was barely sucking air through.

It can’t be the thermostat, because the car runs at operating temp as long as air is flowing through the radiator. I also just replaced the thermostat 1k miles ago. The fan fuse is also still intact, and has not blown.

I reckon I’m due for a new fan unit based on your troubleshooting combined with mine. What do you think?
 
originalmarshmello said:
I’m in a very similar boat as you were. I have an 09 Mazdaspeed3 with 154k miles, just over 2k on the new engine I installed.

The other day, it was 90 out and I was in the inn n out drive thru, car started getting hotter. I knew the fan turns on around 217ish, so I ignored it as it climbed up a bit. Soon it was too hot for comfort in 230s, and I turned off the car to keep it from heating up more. Later on, I got home and checked the fan for power. Hooked it up to direct power bam it worked. I also noticed I was low on coolant, so I assumed that it had just not had enough to trip the temp sensor in the engine to engage the fan. Fast forward nearly a month, which was today. Did some slow traffic driving, and the car got hot again this time, I hopped out and checked coolant. It had coolant.

When I turn on my ac, the fan goes on for a handful of seconds, then off for a handful. This repeats indefinitely as far as I know. When I got the car up to fan engagement temp, it would do the same thing. On, then off, over and over. This was at the lowest speed too, so it was barely sucking air through.

It can’t be the thermostat, because the car runs at operating temp as long as air is flowing through the radiator. I also just replaced the thermostat 1k miles ago. The fan fuse is also still intact, and has not blown.

I reckon I’m due for a new fan unit based on your troubleshooting combined with mine. What do you think?
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With how easy it was for me to test the new module, I would absolutely give it a shot. Your symptoms sound the same as mine. You can just order a new module with fan and plug it in outside the car and see if it’s working properly and then do the full swap once you confirm!
 
Brado said:
With how easy it was for me to test the new module, I would absolutely give it a shot. Your symptoms sound the same as mine. You can just order a new module with fan and plug it in outside the car and see if it’s working properly and then do the full swap once you confirm!
Click to expand...

You said the A/C turned the fan all the way on, right? Not just here and there?
 
originalmarshmello said:
You said the A/C turned the fan all the way on, right? Not just here and there?
Click to expand...
Correct! The AC being on should kick the fan on full tilt if I recall correctly. In any case, it was evident my old one was faulty as it stopped spinning shortly after being powered whereas the replacement one kept going.
 
Update:
I bought a new aftermarket 09 mazda3 fan online since it was a lot cheaper. I then took and tested it against my fan by turning on the A/C while the car was on. The fan should be running constantly at a medium speed when the A/C is on. The new fan runs like it should, and my old one is still on and off.

Then, I removed the old fan and removed the motor and turbine from the shroud. While I could have taken and directly swapped the mazda3 fan, the fan shrouds are different. The 09 Mazdaspeed3 shroud has flaps that open when on the freeway, allowing for more cooling, but the Mazda3 shroud does not. This is why I swapped my new motor into the old shroud.

I had to get creative mounting the new fan control unit, as the mounting holes were different. After some creative thinking, I was able to use one of the holes and the supporting plastic to secure the control unit.

After I swapped it in, the fan actually kicks on enough to keep the car from overheating. So glad this worked! It only cost me about $100 and some time to do this, very much worth it if you can’t find a used speed3 fan someone is selling for a deal.
 
originalmarshmello said:
Update:
I bought a new aftermarket 09 mazda3 fan online since it was a lot cheaper. I then took and tested it against my fan by turning on the A/C while the car was on. The fan should be running constantly at a medium speed when the A/C is on. The new fan runs like it should, and my old one is still on and off.

Then, I removed the old fan and removed the motor and turbine from the shroud. While I could have taken and directly swapped the mazda3 fan, the fan shrouds are different. The 09 Mazdaspeed3 shroud has flaps that open when on the freeway, allowing for more cooling, but the Mazda3 shroud does not. This is why I swapped my new motor into the old shroud.

I had to get creative mounting the new fan control unit, as the mounting holes were different. After some creative thinking, I was able to use one of the holes and the supporting plastic to secure the control unit.

After I swapped it in, the fan actually kicks on enough to keep the car from overheating. So glad this worked! It only cost me about $100 and some time to do this, very much worth it if you can’t find a used speed3 fan someone is selling for a deal.
Click to expand...
Nicely done! Luckily I picked up the Speed3 fan for $104, but likely would have done similar to your situation had there not been an available option. Glad it worked out using the Mazda3 parts and your issue is resolved!
 
lucas413 said:
hey, are you sure that second link will work seems like its for a 2010 +
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Good catch Lucas! That fan does appear to be listed for 2010 + models. However, after a close inspection the connectors seem to be identical, so it should plug and play fine.
Also, the housing of that fan looks like it has identical mounting points as the OEM fan. The control unit is mounted in a different spot though, so that theoretically could be a fitment issue.

Personally, I would go for it and if it doesn’t work send it back since it’s Amazon prime.

Does anyone else have any insight on this?
 
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