Hi, this is Bo, an auto expert on RepairPal's Car Genius team!
Alright, so your Grand Prix is giving you the cold shoulder despite having a good blower, thermostat, and fuse. If you're still blowing cold air, I'd put my money on a heater core issue or a blend door actuator problem.
The heater core could be clogged or have restricted coolant flow, so feel the hoses running to it. If one is hot and the other is cold, you’ve likely got a blockage. Flushing the heater core might bring it back to life.
Now, if the heater core checks out, focus on the blend door actuator—this little motor directs air between hot and cold. If it's stuck or broken, you'll get an Arctic blast regardless of your settings.
As for the interior light fuse blowing, you’ve likely got a short somewhere. It might not be directly related to your heating issue, but an electrical gremlin is worth tracking down—check wiring near the fuse box or around the blower motor for frayed insulation.
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