Beyond just being a bad idea for a homeowner to attempt, handling refrigerant is actually federally regulated in the United States, which is worth knowing both for your own safety and to understand why a legitimate HVAC company will never let you "just add a can of refrigerant" the way you might top off motor oil.
EPA Section 608 certification
Under the federal Clean Air Act, technicians who purchase, handle, or work with most refrigerants are required to hold EPA Section 608 certification. This exists because refrigerants can have significant environmental impact if improperly vented or released, and because handling pressurized refrigerant systems safely requires real training.
Why this matters for homeowners specifically
It's part of why refrigerant can't legally be sold over the counter to just anyone for DIY use the way it may have been decades ago, and it's part of why a legitimate HVAC company's technicians carry this certification. If a contractor is willing to sell you refrigerant to add yourself, or lets you handle it directly, that's a sign worth paying attention to.
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