KJHXXX
Posts: 7
Joined: Mon Sep 19, 2016 8:29 am
Location: Kernow, UK

Fan noise when pulling away

Sun Jan 07, 2018 12:35 pm

Hi all,

I have a 2016 94Ah REX (UK Spec) and I've recently noticed that when pulling away and getting to approx 10mph a relay clicks in the dash and a fan noise starts in the back somewhere. It sounds like (and could be) the REX cooling fan starts to run and then switches off if the speed drops again or after some time - bit tricky to tell.

I've never noticed this before and its annoying. There is no petrol in car so I know it's not the REX starting and I've tried switching off the AC / heating to eliminate this as well.

Any ideas?

Thanks.

Gif
Posts: 234
Joined: Mon Jun 06, 2016 12:24 pm
Location: Bottom right hand corner of Wales

Re: Fan noise when pulling away

Thu Jan 11, 2018 12:32 pm

I’ve recently noticed this too. The symptom is very similar to your description but if I keep the stereo off, I notice it at other times too.

A definite relay switch from around the glovebox area switching something that makes a kind of quiet distant whirring sound from somewhere in the rear floor. It seems to switch on and off within maybe 5-10 secs in mine.

It’s not rex and it’s not cabin ventilation as far as I can tell. I did wonder about the pump to circulate coolant / heating through battery ???

Any ideas anyone?

Funny thing is, I can’t recall hearing it from new but I generally drive with music playing.

jadnashuanh
Posts: 4090
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Fan noise when pulling away

Thu Jan 11, 2018 8:47 pm

Could it be the pump pressurizing the REx's gas tank? It wouldn't need to run very long, but if your tank was essentially empty, the air in there will expand and contract more than just the gasoline, and could run longer. It would also be more prevalent when there's a big temperature change.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

KJHXXX
Posts: 7
Joined: Mon Sep 19, 2016 8:29 am
Location: Kernow, UK

Re: Fan noise when pulling away

Fri Jan 12, 2018 2:22 am

Hi all. I'm starting to think that it is indeed the pump for the battery heating and cooling. Perhaps this is linked to the cold weather at the moment but I've never noticed this noise before. i might try and see which relay is clicking over and that should explain it!

Gif
Posts: 234
Joined: Mon Jun 06, 2016 12:24 pm
Location: Bottom right hand corner of Wales

Re: Fan noise when pulling away

Fri Jan 12, 2018 4:24 am

jadnashuanh wrote:Could it be the pump pressurizing the REx's gas tank? It wouldn't need to run very long, but if your tank was essentially empty, the air in there will expand and contract more than just the gasoline, and could run longer. It would also be more prevalent when there's a big temperature change.

Don’t think so as on mine it’s off and on constantly. Plus my Rex is full so unlikely to take much work to do it. Without knowing the method behind this though, it’s difficult to say.

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