ASA5520 fan question (very loud every once in a while)

[spencerlin1991]

I have a Cisco 5520 in the LAB, and every once in a while the fans start to go very loud for about 2 minutes, it is running the latest IOS, is it normal or the fan is bad? any solution to make it silence while running? 

thank you so much.

[Rejohn Cuares]

Check the device temperature - show environment.

Graph the historical data using SNMP monitoring tools like cacti, Nagios, etc. so

[kcrane2]

There is no show environment on the ASAs, at least not the non -X versions.   I have a new-to-me 5550 at home that was doing the same.   Fans ramped up to turbine speeds and then back down with a minute or two between.   I opened the cover and left a gap at the rear to let in more air, also directed a small fan towards the back and that seems to have stopped it for now.   I have no idea if that will hold up or if there is a bigger issue brewing.   

No TAC support on this guy.  My basement is cool and all but not the kind of cool that data center racks usually are so it could be something to do with that.  I have no frame of reference to go on.

[spencerlin1991]

hello

i just opened the cover, and i think i found the cause of the issue. if the asa running without the cover, the fan is running normally, if i put back the cover, the fan starts speed up with very loud voice. the room where the asa is placed is not cool. any way to solve it without place it on cool environment or leave the cover open?

[kcrane2]

I discovered my solution the same way.   The fans did not kick up to high when the cover is off but that also prevents air from flowing over the heat sink.   Instead I closed the front edge and propped open the back edge with a pencil eraser.   That reduced the frequency of the fans spooling up.   Then I directed a small table-top fan towards the ASA and that stopped the fans from speeding up at all.  

Further experimentation suggests that I can forgo keeping the case cracked open as long as I keep cool air circulating with the table-top fan pointing towards it.   

It's been running now that way for 12hrs.

[spencerlin1991]

i researched, saying that ASA has built-in temperature sensor, if the temperature is higher, the fan will speed up. so the only solution is to make it cool.