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Question

Error Code 90B HP Laptop Cooling Fan

Apr 3, 2020 1:49PM PDT

My cooling fan was really noisy on HP 15-BA-113C laptop. I replaced it and everything seemed ok. After a few reboots the error code started to appear on startup. The fan is turning and moving a good volume of air. The Speed Fan program initially saw the fan and showed speeds and temps. Now the program displays zero rpm although the fan is turning. Is this a matter i need to resolve before causing harm to the laptop?

Discussion is locked

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Answer
You found the cause.
Apr 3, 2020 3:10PM PDT

That zero RPM is the cause. If you have access to an Oscilloscope, probe the fan speed pin on the fan connection and you should see pulses. No pulses and it's either a bad fan unit or worse a motherboard failure. My test is something we can do in our shop but I can't guess what your background is and what test gear you have.

Without any gear you can try unplugging and plugging in the fan again and hope it was the connection. After that you try another fan.

Some PCs allow one to disable the fan speed error but this can also mean you lose the dynamic fan speed control.

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Answer
Thank You Robert
Apr 3, 2020 4:20PM PDT

Who would think new replacement fan would be defective. I reinstalled the old noisy fan and error code is not present. The old fan is not near as noisy as before the repair and reinstall. Speed Fan program sees the fan and it is running from 3500 to 4000 depending on pc usage.

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That's not what you wrote up top.
Apr 3, 2020 4:39PM PDT

"The Speed Fan program initially saw the fan and showed speeds and temps. Now the program displays zero rpm"...

I take what you write and use that. The fan wasn't defective for a time and parts just like all things adhere to The Bathtub Curve.

Again I don't know if you have the gear to test the fan and signal involved but we use that quick test to learn if it's just a bum fan sensor or something deeper.

If you don't have access to the test gear I'd still look for another fan after I tried the old unplug and plug it back in step. Some techs can't quite get things plugged in solid so at times I've had to pull out our USB Microscope to let them see it up close.

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Laptop Seems To Function Properly Now - No Error Code
Apr 3, 2020 5:17PM PDT

Something lost in translation. The old fan never did display the error code. Only got the code with the new replacement fan. With the
old fan showing no code in your opinion do i still have a problem that needs to be resolved? Thank You Robert.

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In that case it sounds like an incompatible fan.
Apr 3, 2020 7:30PM PDT

Talk to the supplier about getting a HP replacement. Unlike many case fans, these are often specific models for specific boards.