R129 electrics

[wolfman]

1990 SL500 garaged and used only rarely in winter. Have problems with heater/air con controls. The heated rear windscreen is permanently on and cannot turn on air con.I keep the battery on charge.....is it worth disconnecting the battery to allow the system to reset?
Thanks
Wolfman

 

[television]

Is the lamp for the rear screen on all the time,,that could be a problem with the N10 relay, what happens if you unplug the screen.

With the heater or air con,,what part is not working