Fan clutch turns on as soon as I start my Jeep

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The_walrus

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Hello everyone,

My second question on this forum!

I notice my fan clutch will turn on right away I turn on my jeep. I this normal?. I just bought a jeep 2004 x.

Is there a way I can find out if the fan was mod to be on all the time?

Thank you all
 
The_walrus said:
Hello everyone,

My second question on this forum!

I notice my fan clutch will turn on right away I turn on my jeep. I this normal?. I just bought a jeep 2004 x.

Is there a way I can find out if the fan was mod to be on all the time?

Thank you all
Click to expand...

Welcome

Are you talking about an electric fan?
 
I would say to make sure your AC fan is in the off position before you start your Jeep. If it is in the on position, it will come on. On my 97 Wrangler the AC fan switch needs to be completely to the left for the off position. In any other position, the internal fan will come on.
 
ChasUGC said:
I would say to make sure your AC fan is in the off position before you start your Jeep. If it is in the on position, it will come on. On my 97 Wrangler the AC fan switch needs to be completely to the left for the off position. In any other position, the internal fan will come on.
Click to expand...

It is off. That’s why I notice the fan will kick in a couple of seconds after I start the jeep.
 
Mud Mixer said:
Someone installed a heavy duty fan clutch. I put one in mine, it engages at startup.
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I agree, my understanding is that fluid sits for any time in the clutch, and it engages it until it gets moving for a touch. Then it works as intended.

Just my understanding
 
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Mine engages for a short time after cold start up and then stops moving much air. It will always spin a little but basically it's just slipping internally until the thermostat engages it to spin full speed.
 
Link said:
Mine engages for a short time after cold start up and then stops moving much air. It will always spin a little but basically it's just slipping internally until the thermostat engages it to spin full speed.
Click to expand...

I don’t think it’s the thermostat. That’s a pretty simple device that opens and closes, and the coolant flows from the radiator once it opens.

The clutch has its own mechanism that gets to a temp and engages and disengages, same as the thermostat, but work mutually exclusive, to my understanding.
 
cpwolf said:
I don’t think it’s the thermostat. That’s a pretty simple device that opens and closes, and the coolant flows from the radiator once it opens.

The clutch has its own mechanism that gets to a temp and engages and disengages, same as the thermostat, but work mutually exclusive, to my understanding.
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I'm not talking about the engine thermostat. In this pic below, note the spring. It's a thermostatic spring. It expands and contracts with temperature. As the spring senses the engine temp rising, it expands and activates the viscous coupling. As temps fall, it contracts and deactivates the viscous coupling.

https://en.wikipedia.org/wiki/Fan_clutch

Per the wikipedia link it's called the "bi-metallic sensory system"....aka....a thermostat of sorts. Old school dial thermostats use the same mechanism.

https://en.wikipedia.org/wiki/Bimetallic_strip






hda-2747_vy.jpg
 
The_walrus said:
Hello everyone,

My second question on this forum!

I notice my fan clutch will turn on right away I turn on my jeep. I this normal?. I just bought a jeep 2004 x.

Is there a way I can find out if the fan was mod to be on all the time?

Thank you all
Click to expand...

It's not normal for the fan clutch to kick in as soon as you start your Jeep, especially when the engine is still cold. Typically, the fan clutch only engages when the engine gets hot to help cool it down. You can do a Cold Start Test to check if something's wrong. Just start your Jeep when the engine is cold and watch the fan. It shouldn't be spinning fast or making a lot of noise, because the clutch should be disengaged. If the fan's going full speed from the start, there's likely a problem.
 
MichaelCar001 said:
It's not normal for the fan clutch to kick in as soon as you start your Jeep, especially when the engine is still cold. Typically, the fan clutch only engages when the engine gets hot to help cool it down. You can do a Cold Start Test to check if something's wrong. Just start your Jeep when the engine is cold and watch the fan. It shouldn't be spinning fast or making a lot of noise, because the clutch should be disengaged. If the fan's going full speed from the start, there's likely a problem.
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Every vehicle I have ever owned with a mechanical fan clutch has always spun at nearly full speed initially at start up and then within a short period of time (less than a minute but I have never timed it) the fan slows way down and the clutch works as normal.
 
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Link said:
Every vehicle I have ever owned with a mechanical fan clutch has always spun at nearly full speed initially at start up and then within a short period of time (less than a minute but I have never timed it) the fan slows way down and the clutch works as normal.
Click to expand...

This has been my experience too
 
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Does it continue to run, or does it still function properly once @ operating temperature? Sounds like its possibly gone bad and is stuck/locked in the engaged position. How easy/hard is it to turn by hand, obviously with the engine off...lol.
 
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Here is an excellent training video on fan clutches. At 11:38 to 13:38 he explains the 2 reasons why a thermal viscous fan clutch may be engaged at startup for several minutes, and that it is normal behavior.


 
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B1Toad said:
Here is an excellent training video on fan clutches. At 11:38 to 13:38 he explains the 2 reasons why a thermal viscous fan clutch may be engaged at startup for several minutes, and that it is normal behavior.


Click to expand...

Another video that animates how the clutch works. A good 3 minute watch.

 
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