There are no drop-in replacements for R22.

• A. There are some drop-in replacements for R22.
• B. Drop-in replacements for R22 are illegal in some regions.
• C. R22 can always be replaced with a direct substitute.
• D. There are no drop-in replacements for R22.

Answer: (D)

R22 systems were designed around a specific refrigerant behavior, including its pressures, temperatures, and lubricant needs. A true drop-in substitute would have to match all of those characteristics exactly so you could swap refrigerants without changing anything else. No refrigerant achieves that perfect one-for-one match for R22, so simply swapping in a different refrigerant can lead to lubrication problems, improper lubrication of the compressor, valve issues, or mismatched system pressures.

Because there isn’t a flawless direct substitute, servicing or upgrading an R22 system typically involves retrofit work or replacing the equipment to accommodate a chosen alternative refrigerant. While there are common substitutes used in retrofits, they require changes such as oil type adjustments, filters, and possibly component tweaks to ensure safe, reliable operation. This is why the statement that there are no drop-in replacements is considered correct.