A1502 820-3476 Works but no fan spin

[mon2]

Hi. Just received an A1502 (820-3476) that had a damaged LCD panel. The panel has been replaced, unit works fine - chime and all but have yet to see the fan turn on. Not a good sign. Temp is about 40 degrees C on the heatsink.

Will check the mosfet @ Q6060 that is responsible for motor control (J6050).

Have attempted PRAM reset - no difference. The fan / logic board look mint with no dust, no liquid damage / no liquid indicator triggers.

Any suggestions?

Update - fan just turned on via diagnostics. Perhaps a non-issue and the logic board was cold enough as to not trigger the fan?

Please ignore (unless you believe this board is not behaving correctly).

[Offscreen6]

Re: A1502 820-3476 Works but no fan spin

Hi,

Perhaps there is a loose connection somewhere between the fan and the main PC, that keeps it from starting up on boot. Definitely check that the main connector from the motherboard to the fan is properly fitted.

I don't know how you could check if it is a non-issue without just letting it run for long enough until you'd imagine the fan should kick in... of course, that risks overheating the computer.

For some more help, I found this guy working on the same computer, with the exact opposite problem; the chime works but not the fan. I'm no motherboard expert, but maybe that can give you some insight : https://boards.rossmanngroup.com/thr...o-chime.36617/

[piernov]

Re: A1502 820-3476 Works but no fan spin

Are you 100% sure this is a 3476 and not a 4924? If yes run ASD to make sure the fan motor tests and CPU warm-up tests pass.

[mon2]

Re: A1502 820-3476 Works but no fan spin

Hello. Thank you both for your replies.

1) No, we are not 100% confident of the board # as we could not locate the PCB etched markings on the topside (after the bottom lid is removed). The boardview locations for the LVDS, battery connector, fan connector all match the 820-3476.

2) Did run ASD and the tests passed. The ASD testing process enabled the fan spin. The fan connector is factory tight - no one has been inside this machine before us. There is a large block bump pad on the fan FPC cable. Guessing it is to lift up the bottom lid and serves no other purpose.

Just somewhat baffled that the logic board boots upon turn on and does so without a fan spin. Used to fan spin upon power on cycle.

So, is it normal to not have the fan spin on power up (like all other inspected macbooks to date) for this A1502? It is our first A1502 in the shop.

[piernov]

Re: A1502 820-3476 Works but no fan spin

3476 is a 2013 model and has 16 RAM chips without shield over them. (and there's also the 3536 2013 model with 8 RAM chips without shield over them) Model number is near RIO board connector.
4924 is a 2015 model and has 4 RAM chips with shield over them.
You must confirm the board model number or at the very least the full machine model number before troubleshooting as indicated in the Beginner's guideline, you can't troubleshoot something if you don't what it is, and if you give incorrect numbers it just makes everyone waste their time.

[ACS-Repair]

Re: A1502 820-3476 Works but no fan spin

I too was trolled by an A1502 where the fan would not come on at startup. Mine was an 820-4924 that would come on and run for long periods without the fan. I loaded the Macs Fan Control app so that I could see the fan speed and the CPU temps. I could manually turn the fan on with the app so I could see that it was not a problem. For some reason this model will stay cool without the fan.