Problem is probably the strip fuse. Assuming that hasn't fixed it, you can check the control voltages coming off of the pushbuttons. You said you have replaced the regulator, so you know where the connector is under the windshield, on the driver's side behind the power steering. Black is ground and red should be battery voltage. The yellow wire is the control voltage. With low button pushed in, you should have 1DCV. High should be 12 DCV and auto should range in between. I've read that the pushbuttons cannot be repaired or replaced and that you will need to buy the entire assembly for about $200. Some posters have supposedly had success cleaning up solder bridges they found on the the main circuit board. The pushbuttons are on a smaller board you might also check if you are not getting the control voltages.