Doubt it the switches are generally reliable but let down by the wiring which is far more likely, when you say you tested the fans the red wire should of come out the relay but where did you disconnect/find the earth from and I presume you connected direct to battery? Obviously this should be connected to ground as well. Also make sure the other side of fan switch is connected to good earth. You need to confirm that you have +12V first at two relay terminals.

Martin