2001 Grand Am SE dash gauges and blower won't work until I drive for about 20 or 30 minutes (assuming until car is warmed up good). Then I have to tap the dash, hit it hard, hit it harder, tap it a million times and everything will work. Stop somewhere, turn car off, same problem again. Had this issue before along with ignition switch replacement. After ignition switch replacement everything worked fine. Not sure ignition switch is related though. It sounds as though there might be short, loose wire, etc. Please help me somebody. Want to sell this car ASAP and need to fix this.
With the car running and the problem is present, check the fuses for the instrument panel (IPC/HVAC BATT 10 AMP) and IPC/BFC ACC 10 AMP) for power, the same for the blower fuses.
If you don't have power to the fuses when the problem starts and you do have power when it works then I would check the power feeds from the ignition switch to the fuse panels. It is possible the ignition switch is bad.
Also check the ground wires to the body and dash board frame.
The power feeds to the fuses are the key.
Let us know your results.