This 2002 Pontiac Grand Prix GT came in with the complaint that the blower would not work on the lower speeds and that the high blower would work most of the time. A quick inspection of the system also found that when the blower did work on high speed it would have a delayed turn on of several seconds. From experience I wanted to check the ignition switch input to the HVAC CTRL fuse in the interior fuse box. The fuse box is located behind a panel on the right side of the glove box. Simply grasp the pull handle and pull as shown.
The inside of the cover should have a diagram of the fuse box like the one shown below. You have to rotate the diagram around to match the view of the fuse box. Circuit breakers up.
Doing this will lead you to the correct fuse which is the 20 amp fuse two up and two from the left as shown below. With the key switched on there was no power to the fuse. When testing for voltage with a test light or a voltmeter be sure to have the ignition and blower switches on. The fault should also be present. When the fault is not present the voltages may appear okay. This problem can come and go so test this circuit several times if needed. This is indicative of a faulty ignition switch which this body style seems to have a problem with. Pontiac, Buick and Oldsmobile.
Please click here to see how to replace the ignition switch.