NATE Air Conditioning 2 — Questions and Answers
Question 1: What condition is indicated when an air conditioner's evaporator coil is heavily iced over?
- System is overcharged with refrigerant
- Low airflow or low refrigerant charge (Correct answer)
- Excessive outdoor ambient temperature
- High indoor humidity
Correct answer: Low airflow or low refrigerant charge
Restricted airflow or low refrigerant charge causes the evaporator to drop below freezing, leading to ice formation.
Question 2: What is subcooling in an air conditioning system?
- Cooling the suction line below ambient
- Number of degrees liquid refrigerant is cooled below its saturation temperature (Correct answer)
- Reducing condenser fan speed
- Lowering the thermostat setpoint
Correct answer: Number of degrees liquid refrigerant is cooled below its saturation temperature
Subcooling measures how many degrees the liquid refrigerant has been cooled below its condensing saturation temperature.
Question 3: Which EPA section requires technicians to be certified before purchasing refrigerants?
- Section 406
- Section 608 (Correct answer)
- Section 410
- Section 302
Correct answer: Section 608
EPA Section 608 regulations require HVAC technicians to be certified when purchasing and handling refrigerants.
Question 4: What is the purpose of the Schrader valve on a refrigeration system?
- Controls refrigerant flow rate
- Provides a service port for pressure measurement and refrigerant access (Correct answer)
- Prevents refrigerant from reversing direction
- Regulates compressor speed
Correct answer: Provides a service port for pressure measurement and refrigerant access
Schrader valves are spring-loaded service ports that allow gauges and charging equipment to connect to the system.
Question 5: A high-efficiency split system AC rated at SEER 18 performs better than a unit rated at which of the following?
- SEER 20
- SEER 21
- SEER 16 (Correct answer)
- SEER 19
Correct answer: SEER 16
SEER (Seasonal Energy Efficiency Ratio) measures cooling efficiency; higher numbers indicate better efficiency.
Question 6: What does a low suction pressure reading typically indicate in a residential AC system?
- Overcharge of refrigerant
- Condenser fan failure
- Low refrigerant charge or restricted airflow (Correct answer)
- Faulty discharge valve
Correct answer: Low refrigerant charge or restricted airflow
Low suction pressure usually points to insufficient refrigerant or reduced evaporator airflow causing lower evaporating temperatures.
NATE Air Conditioning 2
What condition is indicated when an air conditioner's evaporator coil is heavily iced over?