Some of you noticed that there seemed to be some noise from the vents/chillers during the recent hot days,

Jan hassled them and managed to get this reply

Hi Jan

We recently had a ‘tunnel blockade’, which means we stop train testing to allow workforce to access the tunnels to complete minor rectification works.
Due to this, the tunnel ventilation, over-track ventilation fans and chiller plant were all operating (at high capacity due to the heat) to provide fresh air to workforce in the tunnels and to cool the station.

Ventilation systems will not operate over the shutdown, which is until 14 January (CYP staff will return on 6 January). The chiller plant will continue to operate as required.

Let me know if you have any further questions.

Kind regards, Dan