Anything that alters the facade of a building is generally not approved unless expressly passed in AGM by the society.
In Mumbai use of exterior wall is prohibited by BMC. AGM also not empowered to permit such use. Split AC’s Cooling units can be installed in the Window grills but with the condition that it does not protrude outside the buildings external wall tarnishing the ambience of the Building.
As regards levying penalty the bye laws lays down the procedure. For breach of any bye law general body meeting should prescribe the penalty beforehand. When a breach is noticed the Secretary should take it up in the Managing Committee seeking direction to send notice to member for taking corrective actions. If defaulting member persists the Secretary has to bring it in to Committee Meeting to send notice to member proposing penalty for approval of the general body meeting after giving an opportunity to the delinquent member to represent his case in the general body meeting.
As per bye law is penalty is imposed.
It is important that rate of penalty for a specified action leading to breach of any bye law must be prescribed by general body meeting beforehand. Since exterior wall form part of the approved building plan doing any alteration is not covered by alteration in the flat and as such it is prohibited under BMC Rules. The member has to restore the position to its original and no amount of penalty can allow the member to continue with it.
Apart from what ive mentioned above try taking up the matter immediately with your secretary if it is causing nuisance or bothering you in any manner. And also download the latest society bye laws from the region that you belong to and refer to it.