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Old 01-11-2019, 01:34 PM   #1
aschen
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Default Radiator fans turn but barely

I did alot of searching on this but I cant seem to find what I am looking for. 2006 wrx wagon 135k miles. The radiator fans will spin but they are very weak sometimes requiring a push by hand to start. I have checked all four of the relays and jumped them to be sure. The coolant temperature is reading fine into the ECU. I am leaving the AC on while testing.

Does all this point to the fan motors being shot? Everything seemingly worked fine previously so it seems weird they would both go at once. I suppose I could have been running on one fan for a while. It just seems weird they both do the same thing. Any advice on where else to look?


Resistance of the motor windings or perhaps a ground spot to check?

Thanks
aschen
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Old 01-11-2019, 02:49 PM   #2
dryvby
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Check incoming voltage at fan plug-ins.
If 12V is seen, apply 12V directly to the fan from a stand-a-lone source with some fused test leads.

Checking fans can be very difficult even with the right equipment. Either yours work or they donít, in the latter case youíll just replace them.
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Old 01-11-2019, 02:56 PM   #3
henrymfisher
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I think there are internal clutches that engage once the fan receives a 12 volt circuit. Maybe the clutch mechanisms have either burned out or just gotten old and slow to engage.
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Old 01-14-2019, 11:11 AM   #4
aschen
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Im certainly no expert but I do not think there are any clutches. I believe them to be simple DC motors? I am not sure how the dual windings work though. Are both of them energized for high speed, or only the high speed winding?
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Old 01-17-2019, 02:59 PM   #5
aschen
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Nobody has any further thoughts? Can anybody recommend where I would check for grounding for the fans? Im not sure where the harness would tie to the chassis for the connectors.

Thanks
Aschen
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Old 01-17-2019, 03:35 PM   #6
rtv900
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There are no clutches so forget that.

I wouldn't bother with ground check either, that would disable them, not make them work poorly.
When electric motors need a push to start its typically the capacitor, but then once they are pushed they work fine, that only affects start up.

So if you put 12 volts directly to them and they still work like crap they either just have horrible bearings due to age or the motors are just toasted for the same reason.
In that case I'd just replace them.
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Old 01-17-2019, 03:52 PM   #7
Charlie-III
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Quote:
Originally Posted by rtv900 View Post
There are no clutches so forget that.

I wouldn't bother with ground check either, that would disable them, not make them work poorly.
When electric motors need a push to start its typically the capacitor, but then once they are pushed they work fine, that only affects start up.

So if you put 12 volts directly to them and they still work like crap they either just have horrible bearings due to age or the motors are just toasted for the same reason.
In that case I'd just replace them.
I sorta agree.
I looked at several diagrams, no caps/capacitors.
No clutches.

Most diagrams I saw were......a ground, then a feed to either high speed coil or low speed coil.
I just spun a few different years and models, basically a "mouse fart" should make the fan spin.
Look for leaves, etc. holding back the fan.
You can pull a fan, check for continuity across 3 pins. One should be common, the other two should be open between them, but common to a single one (likely black).
Apply 12VDC from common to the other two,,,,,,,,,,fan should spin under power.

Clutches are more common on US V8's where it is a thermostatic clutch. Clutch gets hot, engine power drives the fan.......
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Old 01-18-2019, 01:27 AM   #8
Jedi03
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usually what I see when this happens is either blown fuse or bad relay, usually there are 2 one for low speed an another for high
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Old 01-18-2019, 09:29 AM   #9
Charlie-III
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Quote:
Originally Posted by aschen View Post
I did alot of searching on this but I cant seem to find what I am looking for. 2006 wrx wagon 135k miles. The radiator fans will spin but they are very weak sometimes requiring a push by hand to start. I have checked all four of the relays and jumped them to be sure. The coolant temperature is reading fine into the ECU. I am leaving the AC on while testing.

Does all this point to the fan motors being shot? Everything seemingly worked fine previously so it seems weird they would both go at once. I suppose I could have been running on one fan for a while. It just seems weird they both do the same thing. Any advice on where else to look?


Resistance of the motor windings or perhaps a ground spot to check?

Thanks
aschen
With the key off, are they hard to spin? They shouldn't be. If they are they could be failing or have debris between the fan and motor.
If they spin easy, then power directly to them would tell if it's the fan or somewhere in the wiring.
There are several grounds in that area. Some go to inner fender, some to the box beam of the chassis, just look for them, back off the bolt 1/2 a turn or so, then snug back up.
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