So my blower quit working a couple of weeks ago. It will not work on any of the settings, 1-4. Though I noticed that if I turn the A/C on while I'm driving fast enough, cool air will come through the vents. So it seems like the A/C is fine.

I checked the blower motor, resisters on top of it, and both work fine. So we figured it was the heater relay under the hood. We used wire to bypass the switch side of the relay. And like magic, the blower worked like it should on all settings (so the switch works as well). So at this point I assume it's the relay and put down $40 for a new one. Pop the new one in and NOTHING HAPPENED! Now I have two relays and no working blower.

With the exception of being sold a bad part, does anybody know what the problem might be?

Does anybody know how to check to see if a relay is bad?