MacBook – How many fans does a 2.26 GHz 15″ 2009 MacBook Pro 5,5 have

It could be an app or a service running in the background, f.e. mdworker (Spotlight) hung up on indexing a file.

Have you checked with Activity Monitor.app (in /Applications/Utilities/) if there is anything taking up an unusual amount of cpu-time?

Also a quick look into the console would perhaps show some related errors. Post anything that seems out of the ordinary here.

Just to be sure: Have you installed any Software recently, like 'FanControl', 'HDD Fan Control' etc., and deleted it afterwards? I had one case in which the same symptoms appeared after an unclean uninstall.

Yes, your MacBook Pro supports 2.4 GHz & 5 GHz but not simultaneously. All Macs manufactured since 2007 with integrated Wi-fi support 802.11 a/b/g/n and and some 2006 Macs support 802.11 a/b/g.

Only AirPort Base Station and Time Capsules released in March 2009 or later can operate simultaneously over both bands.

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