9300 carrier weather maker 9200. The blower will not run off the air blowing is not heated. I tuned off the heat at the thermostat, and fan will not stop blowing. If I turn the temp on thermostat above room temp it says heat on but no heat come from bents. IF I turn it below temp of room it note no heat on but fan keeps blowing CANNOT turn off fan except at electrical fuse bow. By tripping fuse to off. I changed the filter and batteries in the thermostat. Any suggestions

If this is a limit switch how much does that cause to replace. And the time to do it. Thanks

Look for a flashing light on your control board, in the air handler compartment, and tell us what the flash sequence is. Limit switches, if what this is, are inexpensive and easily replaced. However, most Hi Limit switches reset, some automatically, some with a pushbutton on the switch. Could also be a rollout switch.