dpb wrote:
All other posts (so far) reasonable suggestions altho ditching the new
central A/C for a window unit seems extreme before finding out more...

Actually, it seems extremely pracitical for a couple reasons.
1. The bill is big enough to be big problem for OP, who needs to cut it
_now_.
2. There is possible problem with t-stat and/or a/c sizing.
3. Central air cools way more of house, possibly, than you'd want to
pay to cool.
4. Insulation (toss in sealing) is suspect too, causing a/c to try to
cool the county.
5. Efficience of central a/c is suspect.

I'd ditch the money/energy sucker in a heartbeat.

HTH,
J