The key task a technician should perform as part of a preventive maintenance plan for PCs at a construction site is to remove dust from intake fans. Dust accumulation is common in construction site environments and can cause overheating and failure of components due to impaired cooling. Cleaning the fans helps prevent hardware damage and ensures the PCs run efficiently. Additional preventive maintenance tasks include:

• Regular cleaning of computer components such as air vents, keyboard, mouse, and screen.
• Inspecting power supplies, cords, and surge protectors for dust, damage, or moisture.
• Keeping software updated and performing regular malware scans.
• Backing up data to prevent data loss.

However, the most critical hardware maintenance task at a dusty construction site is specifically cleaning out the dust from the intake fans to prevent overheating and hardware failure.