PowerBook G4 1GHz fan runs constantly

Thanks for your response.

Well, the little darlin's been asleep for a while, so I woke it up. No fan for about 10 minutes this time; I opened Safari and went to Yahoo, then opened Illustrator, nothing taxing, but still no fan. Then I connected an external disk and opened some windows, preparing to install some System updates. Now the fan came on.

It sounds like just the one in the right rear, I.e. the power supply fan -- perhaps because of the power draw from the external HD? I disconnected the power adapter, but the fan still continues ten minutes later. And earlier when I wrote the above, from how loud it was I'm guessing both fans were going, though there was no external HD connected at first, and all I'd done was start it up and run Software Update.

I disconnected the external HD; with the power adapter still disconnected (running on battery), the fan is still going: air coming out the vent on the right side, but not in the back or on the left.

Now the fan has stopped. Activity Monitor shows itself using 3.5% CPU, SystemUIServer using 0.5%, everything else at 0.

Connect the external bus-powered FireWire HD again, and the fan comes on again in a minute or two. After ten minutes or so I disconnect the external HD, then the power adapter; fan still on, stops after five minutes. Which reveals that the CPU (center) fan is running, though the computer's doing nothing other than displaying the Finder.

Ambient temperature's about 80F; humidity is 3% here in the high desert. The PB is sitting on a table on its rubber feet, so it has some air flow. The bottom is warm, but I wouldn't call it hot; I can rest it on my hand with no discomfort.

I have a 12" PowerBook (1.5GHz); I've noticed its fan comes on a lot (more than my MacBook Pro 17" 2.5GHz, which commonly has maybe a dozen apps open but seldom makes fan noise - though I know its fancy variable fans can be quiet), but it does have to be doing some actual work first.

This TiBook crams twice the speed into the case originally designed for the first 400/500MHz model, so I guess it shouldn't be surprising if it runs a little hot. It seems excessive though for the fan to be running all the time even when the computer is idling. Constant fan noise drives me nuts, like a ringing phone it feels like a demand that I DO SOMETHING. I'll be asking the owner of this TiBook tomorrow if she's used to it doing this.

+Hope you'll post back with her reply, but from what you've said, this behavior sounds normal. 80 is a bit higher than "normal;" if I remember correctly, my 867's fans will also start after 10-15 minutes when the temp is that high.+

She says yeah, the fans are on a lot but she hadn't really noticed it. This is her first Mac, bought a year or two ago I think, so she has nothing to compare it with; while I've been using and working with Macs for over 20 years and have always hated the few models with loud, hyperactive fans. A few years back I put a G4 CPU upgrade in my 'Pismo' PowerBook, but soon removed it because it ran hot enough to start up the fan (a real screamer) frequently. My next Mac after that was a 17" 1.5GHz PowerBook whose fans tended to run a lot; I spent a lot of time struggling with it on that account. Anyway, she doesn't seem to mind it, so I'll just proceed now I'm fairly convinced the behavior is "normal".

+One thing that may help is to raise the rear of the PB an inch or two, while making sure there's still air space under the front.+

I put felt furniture feet on the bottom of my portables, both to give them a little air circulation and so they'll slide easily on the desk; I'll probably do that with this PowerBook as well.

Thanks again for your comments.