Government Rebates
The Ontario Government is offering air conditioner rebates to home owners that switch out their current cooling system for a new more efficient unit. The air conditioner rebates value will change according to the new system you install but you can expect to save on energy costs on top of the offered incentives. 
You can expect a Government rebates of $250 on any air conditioner with a SEER rating of 14.5 or better. You will need to get a home energy audit on your home (find out more and get one here) which is a government sponsored program that enables home owners to discover how efficient their home is and where improvements can be made. Once this program or audit has been completed you will be mailed a cheque with the value of the rebates that you should receive pertaining to your upgrades.
Provincial air conditioner rebates are available to all of the greater Toronto area and all cities within Ontario. Any Air Conditioner with a SEER rating of 14.5 or higher will qualify you for a rebate of $250.