AC300 Fan constantly running regardless of load or temperature

I have an AC300 with 4xB300’s that I’ve been using successfully for a few months now. I’ve noticed that the fans constantly run full blast and the unit loses 15 - 20% power overnight with no AC or DC load on the system and obviously not accepting any solar charging. The unit is in my basement so the temperature is 50 - 60 F at any given time no warmer or colder. Here’s a video showing the unit in operation with little charging and no AC load: https://photos.app.goo.gl/XydWc2hmnmBwmhoBA

I’ve seen other YouTube videos demonstrating the operation of this unit and the fans are not running and/or anywhere near as loud.

https://www.youtube.com/watch?v=t4VtcQHEMZc 4:26 Will Prowse starts up the AC300 - no fan noise.
https://www.youtube.com/watch?v=0Q5_L2N0BQ0 Will applies roughly 2500W load to discharge
https://www.youtube.com/watch?v=9XW48sdxsv0 Hobotech applies over 3KW at 9:20 and there’s no fan. At 13:48 he’s charging max at 50V (~600W) and there’s no fan and all throughout the video he has the unit on and the fan is not constantly running.

I’ve tried contacting bluetti service but they’re being combative and refusing to look at my unit or help troubleshoot. Can anyone suggest?

@OhioIsEveryWhere The starting of the fan is closely related to load power, temperature and charging. Do you mean that under normal temperature conditions, without load or charging, the fan will start?

The fan sound is indeed loud in the video, which is not normal. However, it is possible that the fan has been used for a long time and has accumulated dust, causing the fan shaft to not be lubricated, resulting in greater noise. If you have a vacuum cleaner with high suction power, you can try vacuuming it at the fan grille to see if it has any effect.

If it doesn’t work, it needs to be repaired. Could you please provide me with your order number so I can contact the responding department to help you? Thank you.

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The temperature is definitely normal as the unit is in my basement which is a constant cool and comfortable temperature. My video shows no AC load and charging 136 watts via solar. I did vacuum the fan as suggested and I made another video showing the fan still running at top speed after that.

There were also some alerts that were unrelated but support wanted to see them so I included them. I also include the serial number in the video.

The order number is H3816-274255 from Home Depot. The invoice also says “Internet #323358071” if that helps or I can send you the PDF of the order privately.

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@OhioIsEveryWhere Please provide me with your email via PM. Then the CS department will contact you.

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Thank you @BLUETTI_CARE . As stated above, @OhioIsEveryWhere please DM over your email address to Bluetti and they will get in touch. Thanks

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Try using a vacuum cleaner on the inlets to the fan. Some months ago I heard my fans go into a high speed I never heard before. The vacuum cleaner solved that so now I do it once a month.

Now all of a sudden they’re offering me a return so it seems to be progressing. Thanks and I’ll reply if things change. Is it common practise to send a replacement unit and then I ship back the one that needs service, or will I be without a unit for time it takes to service? If the latter then can I purchase a new one from ebay and return it when the original unit is fixed and returned? Thanks.

Per my above post I already vacuumed per Bluetti support directives. This had no effect. It’s probably a simple temperature sensor obstructed somehow but I don’t know how to troubleshoot that.

@OhioIsEveryWhere Usually the latter, you can negotiate with the service department.