My heater motor does not blow any air, I have replaced the motor, checked the fuse, and the switch inside the car and nothing has worked. Does anybody have any ideas? I see a little black box/relay on the heater box under the hood that it looks like the wires run to. Could this be the problem? Any help would be appreciated. Thanks in advance.

 

If it clicks, it's working. See if you can listen to it or feel it with your hand. If it doesn't click then make sure you're getting power to both sides of the relay. The control side and the load side. And check for grounds.