Possible fan clutch problem

[Ric_Whit]

Hi all,

I know this has been talk a lot but I want more opinion about this.

I have a 2002 trailblazer and I have replace the radiator cap, fan clutch and thermostat in 2013 due to overheating with no SES or service lights on.
Sins then the fan clutch sounds like a jet at startup for some second and the temp gauge sit at 1.5 tick before 210 °F with and without AC. Very Good

Three week ago I upgrade the PCM software according Service Update Bulletins (N040032 04032 SOFTWARE UPGRADE MAY BE NECESSARY. REFERENCE BULLETIN 01-06-04-052. 04/21/2004)

Sins the PCM software upgrade the temp gauge is not stable any more sometime it sit at 1.5 tick and other time it sit at 0.5 tick before 210 °F without AC and with the AC on it sit 0.25 tick before 210 °F.

All this is at idle and on the move running.

I have done some testing on the fan clutch and find out that it is very easy to stop the fan with the relay install and removed.
But on the other hand I can feel some good drag on the fan clutch when the engine is off

See this video

PS: Two second after the video the fan clutch come to life and blow a good air but not as hard as before.

May be the fan clutch is dying or is the software upgrade is the cause?

 

[xavierny25]

The gauge on the dash is never 100% accurate so you might need a obd2 to see what temps the fan clutch is cutting in and out.

 

[Ric_Whit]

The gauge on the dash is never 100% accurate so you might need a obd2 to see what temps the fan clutch is cutting in and out.

Hi xavierny25 yes I agree with you about the gauge, but what about the fan clutch that I stop easily and push it in the opposite direction?

 

[Mooseman]

You said that "you" updated the PCM software. Do you have a Tech 2? If so, you have the most powerful test tool available. You can check actual temps and test the fan clutch for engagement with fan RPM readings. At 90% engagement (the max allowed), it should be almost locked up.

If you don't, it's not when it's off that counts. When running, it should be giving some tugs to try and get it going. If you get nothing as the engine gets hotter or with A/C on and running, it's toast.

Just a wild guess, was it a Dorman you installed?

 

[Ric_Whit]

You said that "you" updated the PCM software. Do you have a Tech 2? If so, you have the most powerful test tool available. You can check actual temps and test the fan clutch for engagement with fan RPM readings. At 90% engagement (the max allowed), it should be almost locked up.

If you don't, it's not when it's off that counts. When running, it should be giving some tugs to try and get it going. If you get nothing as the engine gets hotter or with A/C on and running, it's toast.

Just a wild guess, was it a Dorman you installed?

I wish I can have a Tech 2 but I’m not unfortuly.
The dealer updated the PCM software.
GM OEM fan clutch are installed.

What I can add is I think with the momentum of the rpm it have a little drag when I try to stop the fan but as soon it stop I did not feel no tugs I can just push it in the opposite direction.

 

[Mooseman]

Another final test would be to pull the fan clutch relay and jump the connectors to give full 12V to the fan, which should lock it up in short order.

 

[Ric_Whit]

After several testing at any temperature, with or without the relay, with jumping wire and with AC on and off, I can still stop the clutch very easy and push it in the opposite direction.

One thing yes, never ever the temperature has clime high past 210 °F I used an Innova 3160B scan tool.

I guess I have to come to the conclusion that the new PCM software update work like that.

Well I will keep my eyes on the temperature.

 

[Blckshdw]

After several testing at any temperature, with or without the relay, with jumping wire and with AC on and off, I can still stop the clutch very easy and push it in the opposite direction.

One thing yes, never ever the temperature has clime high past 210 °F I used an Innova 3160B scan tool.

I guess I have to come to the conclusion that the new PCM software update work like that.

Well I will keep my eyes on the temperature.

Just as a reference, here are the percentages for the fan speed based on AC pressure and engine temp readings, that the PCM is using. As you can see, with a temp of 210, the fan isn't being asked to spin very fast.

 

[Mooseman]

Conclusion is your fan clutch is dead.

 

[Ric_Whit]

Just as a reference, here are the percentages for the fan speed based on AC pressure and engine temp readings, that the PCM is using. As you can see, with a temp of 210, the fan isn't being asked to spin very fast.

Thanks Blckshdw for the infmation

 

[Ric_Whit]

Conclusion is your fan clutch is dead.

Mooseman even with Blckshdw comment above you think that my fan clutch is dead???

 

[Mooseman]

Yes because when you jumped the relay connections, it didn't lock up. It should have sounded like a jet engine.

@Blckshdw only put that up as reference only.