CoolOps

CoolOps offers a free library of field guides for independent HVAC technicians and small shops in the US. The guides cover refrigerant fundamentals, measurement references, service records, invoices and maintenance checklists, each built around worked examples such as refrigerant logs, service reports and sample invoices. The site focuses on helping technicians document service visits clearly, separate repairs from maintenance, and understand concepts like superheat, subcooling and refrigerant safety classes. Content is free to read with no sign-up required, aimed at practical, everyday field documentation rather than theory alone.