FREE Air Conditioning Repair Installation and Service Procedures Questions and Answers

Question 1

When brazing copper refrigerant lines during an HVAC system installation, what is the primary purpose of flowing a low-pressure, inert gas like nitrogen through the tubing?

Accepted Answer

To displace oxygen and prevent the formation of copper oxide scale inside the pipe.

Answer

To cool the copper tubing and prevent overheating.

Answer

To purge any residual refrigerant from the lines.

Answer

To increase the pressure inside the pipe to test the brazed joint as it cools.

Question 2

A technician is charging a new residential split system that uses a capillary tube as a metering device. According to most manufacturer's guidelines, which of the following is the most accurate method for determining the correct refrigerant charge?

Accepted Answer

Charging by weight, using the specific amount listed on the unit's data plate.

Answer

Charging until the suction line feels 'beer can cold'.

Answer

Adding refrigerant until the sight glass is completely clear.

Answer

Adjusting the charge to achieve a specific evaporator temperature drop (Delta T).

Question 3

After evacuating a system to 500 microns, a technician isolates the vacuum pump and performs a decay test. The micron gauge reading slowly rises before stabilizing at 1,500 microns. What does this most likely indicate?

Accepted Answer

There is still moisture boiling off within the system.

Answer

The system has a large leak to the atmosphere.

Answer

The vacuum pump is faulty and requires service.

Answer

The micron gauge is not calibrated correctly.

Question 4

A technician is searching for a very small, intermittent refrigerant leak in a system that has lost its charge over several months. Which leak detection method is generally the most effective for pinpointing such a leak?

Accepted Answer

Electronic (heated diode or infrared) leak detector.

Answer

Soap bubble solution.

Answer

Ultrasonic leak detector.

Answer

Halide torch detector.

Question 5

A technician servicing an R-410A system measures a suction line pressure of 118 psig. To accurately calculate the superheat, what is the next critical piece of information they need and how is it obtained?

Accepted Answer

The actual suction line temperature, measured with a thermometer near the service valve.

Answer

The head pressure, measured at the liquid line service valve.

Answer

The ambient outdoor temperature, measured with a standard thermometer.

Answer

The compressor amperage, measured with a clamp-on ammeter.

Question 6

During the final commissioning of a newly installed residential air conditioning system, which of the following checks is critical for ensuring proper equipment performance and longevity, in addition to verifying the refrigerant charge?

Accepted Answer

Measuring and documenting the static pressure of the duct system.

Answer

Verifying the thermostat brand matches the condensing unit brand.

Answer

Polishing the copper lineset for a professional appearance.

Answer

Ensuring the disconnect box is aesthetically pleasing.