Pontiac Problems? Ask a Mechanic for Answers ASAP
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This is a very common issue in these cars. The issue is the ignition switch. The fan, speeds 1-4 get power through the ignition switch and the same contact as the daytime light module. SO once you change to speed 5, the load for the blower comes from a different fuse and things come back. Change the ignition switch and you will fix your issue.