This is complicated, and you need to learn and provide more information, to know the best answer in this situation. But generally, if the building’s facilities need replacing or repairing then all the owners must fund this, according to their unit entitlements. It doesn’t matter that only some of the owners benefit from that facility. There is a legal duty under strata law to maintain all the building’s facilities. For example, if the building has a lift, then all owners fund its operation, even though some may live of the ground or lower floors and so not use it. If the building has a swimming pool, then all owners must maintain that, even if they don’t use it.
Nevertheless, this situation might be affected, if the aircon was installed by the owners themselves after the building was built. Of if the Owners Corporation passed a by-law about the aircon in the past, or if the commercial owners have specific by-laws affecting their properties. So you should check your building’s current by-laws, for any of these special arrangements.
You will probably need to raise a special levy, or arrange a strata loan, to fund these repairs. Or if your funds are adequate, use those, with an increase in your future levies to pay that amount back. From experience, loans are difficult to organise – some owners will object to the interest charged, and investors have different views on how the funds are raised to owner occupiers. Best if you involve your strata manager in discussions about how to raise the money, I suggest.