To give some context from the driver's side: there are a lot of aircon faults going on at the moment - on the TCMS we have a HVAC page to view the status, and often (without any fault being raised in the station tab, for ref this is the page that lists all faults) the icon for the saloon HVAC units turns red, meaning it's encountered an error.
It is possible for the more twigged on drivers to turn the saloon HVAC off and on again from the TCMS, which I've done a few times when I've noticed this happening - no idea if it actually fixes the issue but the status colour for the HVAC units stays blue after doing this. Watching it though I can often see that in one unit the temperature stays more where it should be, while the one that had the faulty unit doesn't reduce temperature - which to me says turning the HVAC off and on doesn't really fix anything.
Interestingly I've also seen faults with the cab heaters getting stuck on recently as well, was continuously blowing hot air with the air con then on as well trying to fight against it... had two cabs in the same day doing this. Only solution here is to trip out the cab heating MCB, with permission from maintenance control of course. Does mean you have no heating, only HVAC, which is fine on hot days though.
It does make me wonder if the recent software update that's being applied to the 197s is causing a few unexpected issues, as there are other issues as well like not being able to put the train into coupling mode when uncoupling, which makes reversing off to the 2ft distance more difficult as you don't have the power limited (which is all coupling mode does really, limits max speed and power output - after pressing the uncouple button it should be available to use even though you're not coupling up, just to control your speed).
