Q: My 2010 kia blower fan stopped working but was fine last week. This occurred a few times in past. Works fine then stops blowing ag

The blower switch and the plug connection on the back of the switch, as well as a faulty blower motor are likely, too. I would check the blower motor first as you can easily power the motor directly to see if it runs. If the circuit includes a blower motor resistor block, of course be sure to check if the resistor block has continuity (specified resistance in ohms) at each position. If the blower motor runs, I would check the switch as occasionally there will be a bad connection at the switch that eventually causes the blower not to work. The relay is easy to test and if it works consistently as commanded, you can assume there is no intermittent fault. Obviously, check the fuse in the circuit, too, but if the fuse is bad, that means there is a problem in the circuit that will have to be repaired. Fuses blow due to electrical faults (e,g., short circuits). If you desire, a certified mechanic from YourMechanic can diagnose the problem you are having in an electrical component diagnostic.