When I turn the fan on to use the AC, it will not blow air.
the fan will not blow when turned on. on 2003 Honda Civic
This could be from a bad switch, blower motor, wiring or blower motor resistor. Check the fuses first, then you will need to check for the proper power and ground signal to the blower motor to determine the cause of the problem.
1 more answer
Check your thermastat