Here are two tips to follow if you're getting a commercial air conditioning system for your pet shop.
Ensure none of the vents that are fitted point directly at your small animals' cages
When deciding where to have the contractor fit the system's vents, you should try to ensure that none of them is pointed directly at the cages in which your shop's hamsters, gerbils or other small animals reside.
The reason for this is that if there is a breeze blowing from the vent directly into these cages, not only might the animals in them get too cold but their bedding, which may consist of loose wood shavings, hay, etc., might also get blown around and outside their cages. The constant movement of the bedding could be distressing for the animals, and you might have to spend even more time than you do now sweeping up the bits of bedding that fall out of the cages and onto the floor.
As such, if you're happy with the current placement of the animal cages or if there is no other area in which to put them, then you should ensure that the vents are not placed anywhere that results in them facing them directly. This will allow you to keep the area where these cages are located cool and will also ensure the animals in this part of the shop don't become uncomfortably cold or distressed.
Consider getting a split system
Whilst ducted systems work well in many commercial settings, a split system might be a better choice for your pet shop. The reason for this is that the birds or animals in some areas of your shop might require a moderately high room temperature whilst, on hot days, your customers may prefer to be in a shop that's on the colder side.
If the contractor fits a split system, you'll be able to adjust the temperature of each of its individual units. If you then put one unit near your bird or animal cages, and another unit by the aisles where you keep your pet supplies, you could, for example, make the area where you keep your birds quite warm whilst still keeping the aisles along which your customers will walk fairly cold. Conversely, if you put in a ducted system, it would not be as easy to set different temperatures in different areas of the shop; instead, your only option would be to adjust the angle of the system's vents to control their airflow.