What must technicians avoid when reusing refrigerants?

Technicians must avoid contaminants and mixing different types of refrigerants when reusing refrigerants because doing so can lead to significant operational and safety issues. Each type of refrigerant has a specific chemical composition and properties, and mixing them can produce an incorrect refrigerant blend that may not work effectively or could compromise the system's performance. This can also result in increased pressure or the formation of harmful acids that can damage the equipment and create hazards during system operation.

Moreover, contaminants can also affect the efficiency of the refrigerant, leading to reduced cooling performance and potential breakdown of the system components. Overall, maintaining refrigerant purity is crucial for ensuring the safe and effective operation of HVAC systems.