When sourcing HVAC parts, you must prioritize material compatibility and energy efficiency ratings. For compressors, verify the SEER (Seasonal Energy Efficiency Ratio) and EER ratings to ensure they meet modern energy standards. For heat exchangers and coils, ensure the use of corrosion-resistant materials like high-grade aluminum or copper with hydrophilic coating. Additionally, confirm that motors and fans meet IP54 or IP55 protection classes for dust and moisture resistance, especially for outdoor units.