Objectives

• After studying this unit, you should be able to
• distinguish between mechanical and electrical controls.
• explain how and why mechanical controls function.
• describe an automatic pumpdown system.
• define low-ambient operation.
• describe electrical controls that apply to refrigeration.
• describe off-cycle defrost.
• describe random, planned, hot gas, cool gas, and external heat defrost.
• explain temperature-terminated defrost.
• describe the various refrigeration accessories.
• describe the low-side components.
• describe the high-side components.
• explain the function of a compressor oil pump and oil check valve.
• describe the function of a partition wall in a compressor.

Next: Advance to the Learning Center Dashboard and complete the lessons.