Defrost controls for air conditioning and heat pumps can be temperature initiated/___________________

• A. Temperature terminated
• B. Pressure terminated
• C. Time terminated
• D. Humidity terminated

Answer: (A)

Defrost cycles are controlled by sensors on the outdoor coil, using temperature signals to manage when to start and stop the cycle. When the coil gets cold enough and frost forms, the defrost begins because it’s a temperature-initiated action. The cycle ends once the outdoor coil has warmed to a set temperature, indicating the ice has melted sufficiently and normal operation can resume. Terminating by temperature helps ensure the defrost isn’t longer than needed and prevents wasteful energy use, making temperature terminated the best fit. Some systems may use time-based or other methods, but this item emphasizes ending the defrost with a temperature signal.