How much to replace my heating and air??

4000$-5000$ without new ductwork.

That's a 14 SEER 2 ton American Standard indoor and out.

I would first spend money and have the HVAC checked for proper operation. Next, estimates are usually free from a licensed HVAC Contractor. However I would look at windows, window frames, and insulation before I started spending money on a new HVAC system. True enough your power bill may be due to the ac running a lot, but the question here is, why is it running a lot? Is it due to inefficient equipment or is it due to poor insulation and 80 year old windows and window frames. To answer your origianal question, How Much? I will guess the ceilings are 9 feet tall, 1050 sf, 80 year old home( which whwn built in 1928 had little or no insulation, I would suggest a 2.5 ton 14 seer r410a Payne system with r-8 rated flex duct. For this type of job we would charge $4685.00 10 year factory warranty from Payne and 5 year labor warranty on the installation from us.

$5000 is probably a wildly rough guess. While replacing them with more recent models will probably help, with an 80 year old house you probably need to take a look at what insulation you have. A house of that age would probably have little to no insulation as originally built.

I had a new furnace (gas), new duct work, and chill lines for AC installed during a remodel a couple years ago for about $5000. The AC compressor would have been a couple thousand more. This is for a 1750 square foot house.

$3000 for parts....it's a small house........I would say a good HVAC guy could do it for $4000 total depending on the brand you choose.