HVAC Air Conditioning 2 — Questions and Answers
Question 1: What is the primary purpose of a metering device in an air conditioning system?
- Increase refrigerant pressure
- Reduce refrigerant pressure and control flow into the evaporator (Correct answer)
- Remove moisture from refrigerant
- Filter contaminants from refrigerant
Correct answer: Reduce refrigerant pressure and control flow into the evaporator
The metering device (TXV, orifice, etc.) drops refrigerant pressure and regulates flow entering the evaporator so it can absorb heat and evaporate properly.
Question 2: A system is operating with high suction pressure and high discharge pressure. Which condition does this most likely indicate?
- Low refrigerant charge
- Restricted liquid line
- Overcharge of refrigerant (Correct answer)
- Faulty metering device stuck closed
Correct answer: Overcharge of refrigerant
Both high suction and high discharge pressure together typically indicate an overcharge of refrigerant in the system.
Question 3: What does EER stand for in air conditioning ratings?
- Energy Efficiency Rating
- Energy Efficiency Ratio (Correct answer)
- Electrical Energy Requirement
- Equipment Efficiency Ratio
Correct answer: Energy Efficiency Ratio
EER stands for Energy Efficiency Ratio, which is the cooling output in BTU/hr divided by electrical input in watts at a specific test condition.
Question 4: In a split-system air conditioner, which component is located in the outdoor unit?
- Evaporator coil
- Blower motor
- Condenser coil and compressor (Correct answer)
- Metering device only
Correct answer: Condenser coil and compressor
The outdoor unit of a split system contains the condenser coil, condenser fan, and compressor.
Question 5: What is subcooling in an air conditioning system?
- Cooling the evaporator below its design temperature
- Lowering refrigerant below its saturation temperature in the liquid state (Correct answer)
- Removing superheat from suction gas
- Operating the system below outdoor design conditions
Correct answer: Lowering refrigerant below its saturation temperature in the liquid state
Subcooling is the number of degrees the liquid refrigerant has been cooled below its saturation (condensing) temperature.
Question 6: Which type of compressor uses scrolls (spiral-shaped wraps) to compress refrigerant?
- Reciprocating compressor
- Rotary compressor
- Scroll compressor (Correct answer)
- Centrifugal compressor
Correct answer: Scroll compressor
A scroll compressor uses two interlocking spiral wraps — one fixed and one orbiting — to compress refrigerant with fewer moving parts than reciprocating types.
Question 7: When checking a system for non-condensables, where would they accumulate in the refrigeration circuit?
- Evaporator inlet
- Suction line
- Top of the condenser / receiver (Correct answer)
- Liquid line filter-drier
Correct answer: Top of the condenser / receiver
Non-condensable gases (like air or nitrogen) are lighter and accumulate at the top of the condenser or receiver because they do not condense with the refrigerant.
HVAC Air Conditioning 2
What is the primary purpose of a metering device in an air conditioning system?