System fan not working 90B

For about a week I occasionally got an error message, that fan is not working properly. 90B error.
I rebooted and rebooted until the message didn't appear. The fan was working then. 3 days ago I even did a task that required 100% cpu for a few hours and it was fine, at 70-75C. Yesterday I ignored the warning and booted up anyway, the worst thing that could happen is thermal shutdown I thought. After an hour or so I noticed CPU temp is 70C-80C on almost idle. And the fan is not working properly since. I don't know if it's a coincidence or ignoring the warning and booting up anyway directly caused it. I think it's the former.
I haven't cleaned with compressed air yet as I don't have it right now. I gotta go today buy it. But I doubt it will help much. Now the temp is 65C, plugged off, meaning cpu is running at lowest frequency possible and the system is almost idle.
The laptop is HP Pavilion G6 2260sw

 

It seems like compressed air solved this issue. The fan is spinning correctly now, the dust must have clogged it.

 

It's not solved! The problem returned. Same message and the fan just wasn't working after reboot. Then it suddenly started. Anyone has an idea what's going on?