UPS Fan won't turn off.

[Anonymous user]

Hi everyone, yesterday I received  my new APC  BX1100C-IN and I plugged my PC in it and started using it. It was working all fine but then at night I shutdown my PC before going to sleep and then I noticed that the UPS Fan kicked in, I thought it would stop in short 2mins but it didn't so I decided to turn off the UPS anyway from the "On/Off" button on the UPS itself but much to my surprise, the fan still didn't turn off. I then tried disconnecting it from AC mains but same story, fan didn't stop. At the end I was sleepy and tired to plugged it back into mains with UPS in Off State and I went to sleep thinking that It'll stop by the morning but It's morning now and the fan is still spinning. Can anyone help me figure this one out please?

P.S - I had Air Conditioner running the whole time with room temps at around 20c so I doubt that UPS is overheating due my ambient room temp. 

[BillP · Accepted solution]

Hi Prasoon,

I apologize for this inconvenience, it is definitely not typical for the unit to act in this way.  The fan continued to run when you removed the AC power due to the internal battery.  I would recommend you do a full power off of the unit by turning off the unit, removing the AC power source, and disconnecting the internal battery.  Let the unit sit like this for at least 30 seconds, then reconnect the battery, and plug the unit back into AC power.  This will essentially reset the unit and hopefully correct the issue.  If the issue persists, I would recommend calling into your local APC tech support for possible replacement. 

[Jeet]

Didyo try the steps and did it solve the problem. I face the same issue after purchasing a new BX 100 VA.

[Jeet]

" I would recommend you do a full power off of the unit by turning off the unit, removing the AC power source, and disconnecting the internal battery."

Wont it be risky to open the UPS cabinet to disconnect the internal battery with the fan running as the fan runs continuously as soon as it is disconnected from AC mains ?

[starwood]

i have APC 1500 VA pro , my fan is not stopping and its soo loud my head hurts . please help 

[FKH2024]

iv got the same problem with my SRT1000XLI still continue loud Fan 48dB

[HDG]

I have exactly the same problem with a brand new ups srv1ki-e. In 2026, I can not believe that Schneider has still not solved such a crazy issue.

the ups should turn completely off when instructed to do so by pressing correctly the on/off button ! 
the unit is clearly not over-heating and the fn noise is absolutely unsustainable. Same comment, for normal customer product, the fan should be silent (Noctua class) or close even when it is justified to turn on… it is absolutely insane in a normal office environment (and not an industrial computer room) like this model is also design to address !

A full and clear post from Schneider is absolutely needed to address this issue that seems very common based on simple search on internet. What are you waiting for ??? That all your current customers look for other brands,  or that they hurt themselves opening your unit to silent the crazy fan ?

A correction to your hardware and software to avoid the problem and a better quiet fan are needed now ! 
and a clear instruction on how to reset your unit … hoping that it will wake up with a working turn off function the next time… come on Schneider, you are better than doing near nothing for 14 years apparently to solve this issue !!!

[HDG]

Bonjour,

It is unbelievable that Schneider is shipping out small units to be used in an office environment with such a noisy fan… and that never turns off !

I’ll try your procedure above, but it better work because the noise is simply insane in a private room and when all the equipment attached is turned off. 
fyi, disconnecting from the power is still not enough to quiet it down even after a long time. 
I was buying this Schneider appliance feeling good about myself for putting the price to get a quality product, and tonight I am fighting with it to try to sleep !

do you appreciate the irony ? If your trick does not work the first time (and forever), I will certainly steer all my acquaintance from your products as I simply do not recognize what used to be a symbol of quality in the past.

you also need to post how to change the fan for a decent Noctua quiet one without electrocuting ourselves… this is insane…

[Teken]

All (On-Line) double conversion topology UPS incorporate an internal fan that runs continuously. As the double conversion process creates heat which needs to be dissipated to insure a long service life. If double conversion isn't required then a Line Interactive topology model would probably meet your needs.

As the vast majority of them only engage the fan in these specific conditions: On battery, charging, high load, over temperature.

The specification for sound output for your unit indicates only 50 dB. Which is comparable to a quiet conversation in a living room, moderate rainfall, or the low hum of a modern refrigerator. For reference this is what different levels of dB equates to:

Breathing	10 dB
Whisper	30 dB
Quiet library	40 dB
Refrigerator hum / quiet conversation	50 dB
Dishwasher	60 dB
Normal conversation	65 dB
Vacuum cleaner / traffic	70–80 dB
Alarm clock	80–90 dB
Lawnmower / hairdryer	90 dB
Concert / siren	110–120 dB
Jet engine at takeoff	130–140 dB

[HDG]

Tekken, thanks for taking the time to answer, but you are missing the point.  
posting here is not to have an excuse or a discussion on how hard it is to sleep with 50 db in your bedroom.
in any case, the fan should stop working when the unit is off and a clear processs for that to happen is needed when the unit is faulty as shown in several posts.
also a clear unit number of replacement units would be more useful than your tech line (x type transformer).
finally, a clear guide on how to change for a high quality silent fan … that should have been a marketing choice to add 5$ and have the right fan in the right place.
but with the noisy one in place, then a real added value solution is how to change it (after it stops when the unit is off).
I am an engineer , but have grown to respect that the customer pays my salary eventually ….

[Teken]

This and similar threads have come up over the years forever. You’ll note outside of the fan / unit being defective APC / SE has not changed or incorporated any sort of PWM Fan.

PWM fan technology has existed for decades and is used in billions of hardware products.

Only SE / APC can answer the question as to why they insist on using 1950 technology vs 1980 PWM Fan technology in their hardware.

Regardless, if you don’t care about the warranty and the unit is indeed not defective.

You can simply open the unit up and replace the 24 VDC two pin fan with a quieter one that has similar static pressure and CFM.

Replacing any fan with a quieter one doesn’t automatically equate to the same cooling / heat dissipation requirements!

NOTE: If you intend to replace the existing fan you’ll probably need to reuse the two pin connector or install the correct JST.

Questions Ask . . . 👍

[JamesOConnor]

To really figure this out, we need to know what hardware you are running to ensure the UPS is properly sized for your workload. While a fan running on an unplugged unit usually points to a hardware defect, an overloaded UPS will constantly fight to manage the power draw, which generates excessive heat and triggers the fan.

Could you share a few more details about your setup?

• What are your PC specifications (CPU, GPU, and Power Supply wattage)?

• How many monitors are plugged into the battery backup outlets?

• Do you have any other peripherals connected (routers, speakers, docking stations)?

How to Verify Your UPS Size

The APC BX1100C-IN is an 1100VA unit, which delivers a maximum output of approximately 660 Watts. Here is how to check if that is enough for your system:

1. Calculate your peak wattage. Add up the maximum power draw of your PC components. You can use free online power supply calculators to get a close estimate. Add the wattage of your monitors (usually 30 to 50 watts each) and any other powered accessories.

2. Add a safety buffer. You never want to run a UPS at maximum capacity. Multiply your total peak wattage by 1.25 to give yourself a 25 percent safety margin. This ensures the internal components do not overheat and guarantees you have enough runtime to shut down safely during an outage.

3. Compare to the UPS rating. If your calculated total with the buffer is under 660 Watts, your UPS is perfectly sized.

If your total draw is well over 660 Watts, the UPS is undersized and will struggle to keep up. However, please note that even an overloaded UPS should eventually power down its fan once it is completely unplugged and turned off. If that fan is still spinning this morning, you definitely have a faulty unit on your hands and should seek a warranty replacement.

[HDG]

For the record, I have tried several time your procedure to reset the unit and enable it to shut down properly… nothing proper happened yet. Only way to shut it down is to “turn off” (no output power, but fan still going nuts) and disconnect the battery after unplugging the unit.

i am bringing it back !

knowing how painful it is to go back and forth to one of the few shops carrying it, it is real disappointment.