SPRINGFIELD - Power bill refund checks for Ameren customers will be mailed in two weeks, but refunds for ComEd customers won't come until October, utility officials said Tuesday.

Ameren spokesman Shelley Epstein said almost all Ameren customers will get checks for a minimum of $85 in September. Most customers who heat their houses with electricity can expect more than $300.

The checks will be mailed separately from regular September bills in two weeks, Epstein said, but customers who are behind on their bills will get the money credited to their accounts.

ComEd spokeswoman Arlana Johnson said average customers for the Northern Illinois utility will get a $57 credit to their October bill, and $7 each month after that.

ComEd originally had planned to credit September bills, but Blagojevich's lengthy review of the final settlement pushed the schedule back.

For both utilities, the refunds effectively will reduce the amount of the Jan. 1 electric rate increases by about one-half. Most Ameren customers will receive bigger refunds because they generally saw larger increases than those served by ComEd.

And both utilities warn of using average estimates to determine how much of a refund will come in the mail.

Ameren plans to unveil a Web site soon where customers can see exactly what they can expect.

The $1 billion in payouts were negotiated behind closed doors after public outcry forced lawmakers, utility officials and others to address concerns over high power bills.

"We're glad to get this behind us," Epstein said.