70+ AC Technician Interview Questions and Answers

If the AC pipe is too long, I would cut it to the required length while ensuring proper insulation and functionality.

• Measure the required length accurately before cutting the pipe.

• Use appropriate tools like a pipe cutter for a clean cut.

• Ensure the cut end is properly insulated to prevent energy loss.

• Communicate with the customer about the process and ensure their satisfaction.

The answer to the questions related to AC Technician interview.

• There are four refrigeration cycles: vapor compression, absorption, steam jet, and air cycle.

• There are various types of compressors used in AC systems, such as reciprocating, rotary, scroll, and centrifugal compressors.

• Compressors can have different types of connections, including sweat connections, flare connections, and threaded connections.

• TXV (Thermostatic Expansion Valve) and EXV (Electronic Expansion Valve) ...read more

R-32 gas charging pressures vary; back pressure is typically 5-10 psi, standing pressure around 100-120 psi at 75°F.

• Back pressure for R-32 is generally between 5-10 psi during operation.

• Standing pressure can be around 100-120 psi at ambient temperatures of 75°F.

• Always refer to the manufacturer's specifications for precise pressure values.

• Example: If the ambient temperature is higher, the standing pressure may increase accordingly.

Indoor and outdoor units should ideally be placed 15-25 feet apart for optimal performance and efficiency.

• The distance between indoor and outdoor units typically ranges from 15 to 25 feet.

• Longer distances may require larger refrigerant lines to maintain efficiency.

• If the distance exceeds 50 feet, it can lead to reduced cooling capacity.

• Proper placement ensures effective airflow and minimizes energy loss.

• For example, a 20-foot distance is common in residential installations.

Primary, secondary, condenser pump and AHU are components of HVAC system that work together to regulate temperature and air flow.

• Primary pump circulates chilled water from chiller to AHU

• Secondary pump circulates hot water from boiler to AHU

• Condenser pump circulates water from chiller to cooling tower

• AHU (Air Handling Unit) conditions and circulates air throughout the building

The refrigerant used in a refrigeration system depends on the type of system and its application.

• Common refrigerants include R-22, R-134a, and R-410A.

• Refrigerants are chosen based on their thermodynamic properties, safety, and environmental impact.

• Newer systems often use more environmentally friendly refrigerants like R-410A.

• Refrigerants must be handled and disposed of properly to prevent harm to people and the environment.

Normal ACs typically consume more power than inverter ACs, which are designed for energy efficiency.

• Normal ACs usually consume around 1.5 to 2 tons of power, equating to approximately 1.5 to 2 kW.

• Inverter ACs adjust their compressor speed, consuming about 30-50% less energy than normal ACs.

• For example, a 1.5-ton inverter AC may consume around 1.2 kW, while a non-inverter 1.5-ton AC may consume around 1.5 kW.

• Inverter ACs are ideal for prolonged use, as they save on electricity...read more

There are mainly two types of gases used in chillers: R-22 and R-134a.

• The most commonly used gas in chillers is R-22.

• R-134a is a more environmentally friendly alternative to R-22.

• Other gases like R-407c and R-410a are also used in some chillers.

• The type of gas used in a chiller depends on its design and application.

A U trap prevents sewer gases from entering the air conditioning system by creating a water seal.

• Prevents foul odors: The water in the U trap acts as a barrier to block sewer gases.

• Condensation management: It collects condensate from the AC unit, ensuring proper drainage.

• Maintenance: Regular checks are needed to ensure the water seal is intact and not evaporated.

Safety precautions in a refrigeration system include proper ventilation, regular maintenance, and following safety guidelines.

• Ensure proper ventilation to prevent the buildup of harmful gases

• Regularly inspect and maintain the system to prevent leaks and malfunctions

• Follow safety guidelines and use personal protective equipment (PPE) when working with refrigerants

• Handle refrigerants properly and dispose of them according to regulations

• Be aware of electrical hazards and take ne...read more

Air cooled chillers use air to remove heat while water cooled chillers use water.

• Air cooled chillers have a condenser coil and a fan to remove heat from the refrigerant

• Water cooled chillers have a condenser and a cooling tower to remove heat from the refrigerant

• Air cooled chillers are easier to install and maintain

• Water cooled chillers are more efficient and can handle larger cooling loads

• Air cooled chillers are typically used in smaller buildings or where water is scarce

• Wate...read more

Yes, I am capable of repairing PCB boards of electronic components.

• I have experience in troubleshooting and repairing PCB boards.

• I am familiar with using multimeters, oscilloscopes, and other diagnostic tools.

• I have knowledge of soldering and desoldering techniques.

• I am able to read and interpret schematics and datasheets.

• I have repaired PCB boards for various electronic devices such as air conditioners, refrigerators, and televisions.

Qualifications for railway AC technicians typically include a high school diploma or equivalent, completion of a vocational training program, and relevant certifications.

• High school diploma or equivalent is usually required

• Completion of a vocational training program in HVAC or related field is necessary

• Relevant certifications such as EPA 608 certification may be required

• Experience working with HVAC systems, especially in railway settings, is beneficial

HVAC stands for Heating, Ventilation, and Air Conditioning. It refers to the technology of indoor environmental comfort.

• Heating: The process of raising the temperature of an enclosed space to provide comfort.

• Ventilation: The exchange of indoor and outdoor air to maintain air quality.

• Air Conditioning: The process of controlling the temperature, humidity, and cleanliness of air within a space.

• HVAC systems are commonly used in residential, commercial, and industrial buildings.

• Pr...read more

The weekly off will be decided based on the company's policy and the employee's work schedule.

• The weekly off will be communicated during the onboarding process.

• It may vary based on the project requirements and workload.

• The company may follow a fixed weekly off schedule or a rotational schedule.

• The employee can discuss their preferences with their supervisor.

• The weekly off may also depend on the client's requirements.

• The company may also have provisions for emergency work on w...read more

VRV systems typically use scroll compressors for efficient cooling and heating in variable refrigerant flow applications.

• Scroll compressors are commonly used due to their high efficiency and reliability.

• They provide variable capacity control, adapting to the cooling or heating load.

• Examples of VRV systems using scroll compressors include Daikin VRV and Mitsubishi City Multi.

• Scroll compressors have fewer moving parts, leading to lower maintenance needs.

Refrigeration is the process of removing heat from a space or substance to lower its temperature.

• Refrigeration involves the transfer of heat from a low-temperature area to a high-temperature area.

• It is used to preserve food, cool beverages, and create a comfortable indoor environment.

• Refrigeration systems typically consist of a compressor, condenser, expansion valve, and evaporator.

• Examples of refrigeration include refrigerators, air conditioners, and industrial cooling syste...read more

A 12 time blinking green light typically indicates a communication error with the HVAC system.

• Check the user manual for the specific HVAC system to interpret the blinking light codes.

• Reset the system by turning off the power for a few minutes and then turning it back on.

• If the issue persists, contact a professional AC technician for further diagnosis and repair.

The question is about maintaining -18 temperature while charging gas in Kc compressor.

• Use a refrigerant with a boiling point lower than -18°C

• Ensure proper insulation of the refrigeration system

• Check for any leaks in the system

• Adjust the expansion valve to maintain the desired temperature

• Regularly clean the condenser and evaporator coils

There are two main types of compressors - reciprocating and rotary. Freon gases are a group of refrigerants used in HVAC systems.

• Reciprocating compressors use pistons to compress refrigerant gas, while rotary compressors use rotating mechanisms.

• Common freon gases include R-22 (chlorodifluoromethane) and R-410A (hydrofluorocarbon).

• Freon gases are used as refrigerants in air conditioning systems to absorb and release heat.

• Newer HVAC systems are transitioning to more environment...read more

AC mein mukhya roop se teen prakar ke compressors lagte hain: reciprocating, rotary, aur scroll.

• Reciprocating Compressor: Ismein piston ka istemal hota hai, jaise ki window ACs mein.

• Rotary Compressor: Ismein rotating blades ka istemal hota hai, jaise ki split ACs mein.

• Scroll Compressor: Ismein two spiral elements ka istemal hota hai, jo energy efficiency badhate hain.

R-22 back pressure varies based on system conditions, typically around 60-70 psi in cooling mode.

• Back pressure for R-22 is influenced by ambient temperature and system load.

• In cooling mode, back pressure usually ranges from 60 to 70 psi.

• Higher temperatures can increase back pressure; for example, at 90°F, it may reach 75 psi.

• Low refrigerant levels can also affect back pressure readings.

The resistance of a circuit is measured in ohms.

• Resistance is measured in ohms (Ω)

• Ohm's Law states that V = I * R, where V is voltage, I is current, and R is resistance

• Higher resistance means less current flow in a circuit

• Resistance can be calculated using the formula R = V / I

The sensor voltage can vary depending on the type of sensor and its application.

• Sensor voltage can range from millivolts to volts depending on the sensor type.

• It is important to refer to the sensor datasheet for specific voltage requirements.

• Some sensors may require a specific voltage input for accurate readings.

• Sensor voltage may also be influenced by external factors such as temperature and humidity.

An air-conditioning example is a system that cools and dehumidifies air in a building or vehicle.

• Air conditioning systems use refrigerants to cool the air

• They remove heat and moisture from the air to create a comfortable indoor environment

• Examples include central air conditioning units, window units, and portable air conditioners

The refrigeration cycle is a process that removes heat from a designated area to cool it, using a refrigerant.

• 1. Evaporation: Refrigerant absorbs heat and evaporates in the evaporator coil, cooling the surrounding area.

• 2. Compression: The vaporized refrigerant is compressed by the compressor, raising its pressure and temperature.

• 3. Condensation: The high-pressure vapor releases heat in the condenser coil and condenses back into a liquid.

• 4. Expansion: The liquid refrigerant pa...read more

BLDC motors use electronic commutation, while PGDC motors rely on mechanical commutation for operation.

• BLDC (Brushless DC) motors have no brushes, leading to less wear and tear.

• PGDC (Permanent Magnet DC) motors use brushes, which can wear out over time.

• BLDC motors are more efficient and have better speed control compared to PGDC motors.

• Example: BLDC motors are commonly used in electric vehicles, while PGDC motors are often found in older appliances.