The real issue is the excess heat from losses (breaking, mechanical etc.) [1].

This heats the stone of the tunnels since the tube was built. The heat can't dissipate fast enough. The tunnels get hotter every year.

Because of this the tube has gone from a cool place you escape to in summer, in the early 19th century, to a place you'd look for warmth in winter. And a sauna in summer.

Any air-conditioning system that produces excess heat as a side effect will make this worse.

Even if the passengers on those trains will feel it less.

[1] https://www.wikipedia.org/wiki/London_Underground_cooling