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tundra fan clutch running during cold weather

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tundra fan clutch running during cold weather

Old 12-05-2019, 06:01 AM
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Default tundra fan clutch running during cold weather

Just like the title says - my tundra's fan clutch runs a lot on cold mornings. Apart from startup, which is normal, I can hear it revving higher after accelerating from stops, then it winds down. Engine temp normal, truck runs fine, shifts fine Just something I've noticed more now that my commute has changed from a longer drive to a shorter, more stop and go drive in the mornings. I'm probably wrong about this, but I thought it's designed to run more in hot weather? 08 tundra with 5.7.
Old 12-05-2019, 06:19 AM
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Fan clutch will drive the fan when clutch is cold. Should release in about a mile of driving. Nature of the beast.
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Old 12-06-2019, 05:26 PM
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My 2017 does the same (5.7), almost every startup. Especially 1st start in am.
love the sound!
Old 12-06-2019, 07:22 PM
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I've always wondered why Toyota still uses the fan clutch when just about everyone else has switched to electric fans.
Old 12-07-2019, 06:41 AM
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Originally Posted by LuckyPenny View Post
I've always wondered why Toyota still uses the fan clutch when just about everyone else has switched to electric fans.
I asked my guy to switch it over to electric a while back. He didn't want to do it - said mechanical clutch has less that can go wrong. seems to me that the current setup bleeds engine power and impacts transmission shift points.
Old 12-07-2019, 08:14 AM
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As you note, a fan clutch should disengage rather quickly after cold start up. If it constantly reengages without reason, I would replace it. I've had consecutive OEM fan clutch replacements that were defective out of the box, and I was able to solve the problem only after I switched to an aftermarket Hayden fan clutch. I would try a new OEM unit first, but at least you know, if that one misbehaves too, you have an alternative.
Old 12-07-2019, 09:48 AM
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I think the old school fan clutch is more reliable and would not change it out for electric. The problems they have can be locking up (constant roar) or not locking up enough (engine runs hot at low speeds). As long as it quits roaring after a few miles I'd leave it be.
I have an aftermarket fan clutch in our '98 Jeep (the OE was NLA) and it is for sure noisier but keeps the temps down better, usually at or under 210*F.
Old 12-07-2019, 08:24 PM
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Most OEMs gave up old style fan clutch to gain MPGs. Toyoto sells enough Prius's that their fleet average is never a problem so why make the chagne. They roar and rob power under certain conditions.
Old 12-08-2019, 01:02 PM
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On many applications today when one selects the heater / defroster the AC also works with the system. The AC dries out and defrosts the windows faster but it's also likely that the fan clutch engages every time the unit calls for ac demand.
Old 12-08-2019, 01:39 PM
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The aftermarket HD clutches roar even more than the OE but they cool better under extreme heat conditions, at least that's what I found with the '98 Jeep.
Old 12-08-2019, 05:42 PM
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Originally Posted by Bamby View Post
On many applications today when one selects the heater / defroster the AC also works with the system. The AC dries out and defrosts the windows faster but it's also likely that the fan clutch engages every time the unit calls for ac demand.
The fan won't come on unless the AC pressure comes up, which won't happen in the winter. At least this is how it works on GM vehicles.
Old 12-10-2019, 11:39 AM
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The roar of the fan and the blow off of the vacuum system. Trucks a beast on cold starts.
Old 12-10-2019, 12:49 PM
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Originally Posted by ericinmich View Post
The fan won't come on unless the AC pressure comes up, which won't happen in the winter. At least this is how it works on GM vehicles.
i thought when you turned on the a/c, it also turned on the fans electrically regardless of a/c pressures?
Old 12-10-2019, 02:57 PM
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Originally Posted by Rolandt03 View Post
i thought when you turned on the a/c, it also turned on the fans electrically regardless of a/c pressures?
That might be true for the secondary (smaller) electric fan, but the A/C could not directly activate the fan clutch on the larger fan, since (on the old style at least) those are engaged when they get hot.
Old 12-11-2019, 05:51 AM
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Originally Posted by Pez Vela View Post
That might be true for the secondary (smaller) electric fan, but the A/C could not directly activate the fan clutch on the larger fan, since (on the old style at least) those are engaged when they get hot.
gotcha! i have since moved on from 1980 technology! lol!

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