313D System Installation and Brazing 4

Question 1

When installing a split-system condenser, the minimum clearance from the unit to any wall or obstruction on the discharge (top) side should be:

Accepted Answer

24 inches

Answer

Most manufacturers specify at least 24 inches of clearance above the discharge grille to allow proper airflow and prevent hot air recirculation.

Question 2

What flux is most commonly used when brazing copper-to-copper refrigerant joints?

Accepted Answer

No flux is needed for copper-to-copper joints

Answer

Copper-to-copper joints with high-silver alloy brazing rod do not require flux because the alloy flows well on clean copper without it; flux can leave residues.

Question 3

The liquid line in a residential AC system is typically NOT insulated because:

Accepted Answer

The liquid refrigerant temperature is near ambient and condensation is not a concern

Answer

The liquid line carries subcooled refrigerant near ambient temperature, so condensation does not form and insulation provides negligible benefit.

Question 4

When pulling a vacuum on a newly installed residential AC system, the system should reach and hold:

Accepted Answer

500 microns or below with no rise above 1,000 microns after isolation

Answer

Industry standard requires the system to reach 500 microns or below; after isolating the vacuum pump, the reading should remain stable and not rise above 1,000 microns, indicating a dry, leak-free system.

Question 5

A 'P-trap' installed in a condensate drain line serves to:

Accepted Answer

Maintain a water seal to prevent sewer gases from entering the air handler

Answer

The P-trap's water seal prevents odorous or harmful gases from the drain system from being drawn into the air handler by the unit's negative pressure.

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

(313D) Residential Air Conditioning Systems Mechanic Certification Practice Test

313D System Installation and Brazing 4