@sand07
You still need to be careful here if you don’t have an itemized invoice. Suppose the entire package cost $4000 and you list it all as an “air conditioner” and claim a $300 credit. If you are audited by the IRS, they will ask you to prove that the air conditioner portion was really worth $3000 in order to claim the maximum credit. You have the burden of proving every deduction and credit you claim, and deductions and credits can be disallowed if you have the bad luck to be audited and you can’t prove them to the satisfaction of the examiner.
The credit is not for a “system.” The credit is specifically for an electric powered air conditioner, a gas or oil or biomass fired furnace, and an advanced circulating fan. (if your system is a heat pump, that has a $300 credit and cannot be broken into heating and cooling portions, but since you said furnace and AC, I assume you know what you are talking about.)
