Unfortunately your numbers are wrong. The maximum credit in your case is $500 or less.
The credit for an efficient air con is 10% of the cost up to $300.
The credit for an efficient furnace is 10% of the cost up to $150.
There is a credit for "Advanced main air circulating fan used in a natural gas, propane, or oil furnace" which is 10% of the cost up to $50.
So your credit could be $500, if your invoice lists the costs of the a/c, furnace and circulating fan separately. If your system only lists one overall price, you can only claim the $300 credit. Ask your installer for a written cost breakdown if needed.
And finally there is a $500 lifetime cap on all credits for energy efficient improvements like doors, windows, insulation and furnace and a/c. If you claimed the credit in the past, your credit now will be reduced or eliminated.
