APC Smart UPS 1500 fan never turns off

[BillP]

I bought this UPS:

http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SUA1500

And I noticed that the fan is always on (low rotation) even if I turn it off. I searched the forum for some similar issues:

Referenced content removed

But this thread is too old. I want to know if this issue is common on brand new units bought in 2012. Here it's the data from the UPS:

battery.charge: 100
battery.charge.low: 10
battery.charge.warning: 50
battery.mfr.date: 2012/03/05
battery.runtime: 5460
battery.runtime.low: 120
battery.temperature: 29.7
battery.type: PbAc
battery.voltage: 27.4
battery.voltage.nominal: 24.0
device.mfr: American Power Conversion
device.model: Smart-UPS 1500
device.serial: AS1210230036
device.type: ups
driver.name: usbhid-ups
driver.parameter.pollfreq: 30
driver.parameter.pollinterval: 2
driver.parameter.port: auto
driver.version: 2.6.3
driver.version.data: APC HID 0.95
driver.version.internal: 0.35
input.sensitivity: medium
input.transfer.high: 127
input.transfer.low: 106
input.voltage: 118.8
output.current: 1.23
output.frequency: 60.0
output.voltage: 118.8
output.voltage.nominal: 120.0
ups.beeper.status: disabled
ups.delay.shutdown: 20
ups.delay.start: 30
ups.firmware: 653.19.D
ups.firmware.aux: 11.03
ups.load: 13.6
ups.mfr: American Power Conversion
ups.mfr.date: 2012/03/05
ups.model: Smart-UPS 1500
ups.productid: 0002
ups.serial: AS1210230036
ups.status: OL
ups.test.result: No test initiated
ups.timer.reboot: -1
ups.timer.shutdown: -1
ups.timer.start: -1
ups.vendorid: 051d

Any hints to disable this behaviour? I want the fan to turn on ONLY when needed (when using the battery) and I want it to turn off when I turn it off (for now I have to unplug from the wall and "braindead" it, pressing the power off button until it turns completely off the fan). Thanks.