Originally Posted by AzPete
Have you used a volt meter to check for power at any of the relays and plugs? That is the only way to really verify what is happening.
As a temporary fix to drive the car, you could wire the fans to a manual switch that you turn on when the car is running. That would also verify the fans work.
+1. You most likely have an electrical issue. you need to narrow it down to where the problem is, using a voltmeter. Could be that power to the relays is not there (although both low and high are different fuses), or the pcm signal to trigger the relays (ground one side of the coil) is not occurring. Until you track it down to a specific part of the circuit, you can't be sure what is causing it.