Have carrier furnace, the thermostat reads -ac blower motor runs, have on all the time, pre blower works also, if set at 75 it clicks on like it wants to work then -ac pops up on thermostat, tried new batt in thermostat. Any help would be appreciated.

Exact brand and model number of thermostat and sub base if installed.

Sounds like a Honeywell Chronotherm is losing low voltage power ("AC" on the display is telling you so). The continuous blower operation is the result of an open limit device or low voltage fuse. Look for a status LED on the unit. If flashing, it will provide a clue.

I see you have your crystal ball working again. LOL

Abra-cadabra,, there now its fixed

The crystal ball is hosed. I've turned to the bowling ball.;)