820-3427 MacBook Air (Early 2014) fans spinning on high and power button not working.


New member
This MacBook was liquid damaged. After cleaning, no components were replaced as everything other than a few keys on the keyboard was working good.
I ordered a replacement topcase, and after installation, the power button doesn't work and the fan is running at full speed.

I've tested the board with two top cases, two trackpads and two IPD flex cables. That leaves me with thinking the issue is board related. No matter what the combination of parts is, the power button still does not work (every other key works) and the fan is running at full speed.

How would I begin trouble shooting? Do I start with the IPD Flex Connector?


Staff member
Anything funny around R5170, U5110? Also run ASD to see what sensor is failing, I bet $50 it's TS0P.


New member
Louis, you are a genius! There was a little bit of corrosion that I missed right under U5110. I removed U5110 and PIN 8 that goes to PP3V3_AVREF_SMC is gone.

I'm guessing I'm going to have to run a wire since the pad is non existent.