That to me seems to be a harsh and unjust by law
The act makes it possible to repeal such by laws, though it going to cost you money
I say its harsh and unjust, because these days new apartments are sold with air con, and its not unreasonable to expect owners of older apartments to retro fit an aircon.
Your by law may have stood some chance if it said only with the approval of the owners, but a blanket ban is unacceptable.
Seems strange to make such a bylaw, because it devalues each lot by not having air con, an appliance most people expect in an apartment, or at leas the right to install one.