Air Conditioning Repair Installation and Evacuation Procedures 2 — Questions and Answers
Question 1: What is the minimum recommended vacuum level (microns) before closing service valves and charging a residential AC system?
- 500 microns (Correct answer)
- 1000 microns
- 2000 microns
- 5000 microns
Correct answer: 500 microns
Most manufacturers and industry standards require a vacuum of 500 microns or lower to ensure all moisture and non-condensables are removed.
Question 2: When installing a split-system AC, the indoor air handler should be level or slightly tilted in which direction?
- Tilted slightly toward the drain outlet (Correct answer)
- Perfectly level in all directions
- Tilted slightly away from the drain outlet
- Tilted toward the refrigerant line set
Correct answer: Tilted slightly toward the drain outlet
The air handler should pitch slightly toward the condensate drain outlet so gravity assists condensate removal and prevents pan overflow.
Question 3: Which tool is used to flare the end of copper tubing for refrigerant line connections?
- Flaring tool (Correct answer)
- Pipe cutter
- Swaging tool
- Tube bender
Correct answer: Flaring tool
A flaring tool is used to create a conical flare on the end of copper tubing that mates with flare fittings for leak-free refrigerant connections.
Question 4: What is the purpose of installing a P-trap on a condensate drain line?
- To prevent sewer gases from entering the unit (Correct answer)
- To increase condensate flow rate
- To filter debris from condensate
- To measure condensate volume
Correct answer: To prevent sewer gases from entering the unit
A P-trap creates a water seal that prevents sewer gases and odors from being drawn into the air handler through the drain line.
Question 5: During a standing vacuum test, if micron gauge readings rise rapidly after the pump is isolated, this most likely indicates:
- A leak in the system or connections (Correct answer)
- The vacuum is too deep
- Normal refrigerant outgassing
- The gauge is malfunctioning
Correct answer: A leak in the system or connections
Rapid micron rise after pump isolation indicates a leak allowing air or moisture to enter the evacuated system.
Question 6: What is the correct sequence for connecting refrigerant manifold gauges to a system?
- Low-side blue hose to suction, high-side red hose to liquid/discharge, center yellow hose to refrigerant source (Correct answer)
- High-side red hose to suction, low-side blue hose to liquid, center hose to vacuum pump
- Center yellow hose first, then high-side, then low-side
- Low-side to discharge, high-side to suction, center to manifold
Correct answer: Low-side blue hose to suction, high-side red hose to liquid/discharge, center yellow hose to refrigerant source
Standard manifold gauge protocol connects blue (low) to suction service port, red (high) to liquid/discharge port, and yellow center hose to refrigerant cylinder or vacuum pump.
Question 7: When running refrigerant line sets through walls or floors, technicians must use:
- Grommets or bushings to protect tubing from abrasion (Correct answer)
- Standard drywall anchors only
- PVC conduit rated for gas service
- Metal strapping without cushioning
Correct answer: Grommets or bushings to protect tubing from abrasion
Grommets or bushings protect copper refrigerant tubing from abrasion at wall penetrations, preventing wear-through that could cause leaks.
Air Conditioning Repair Installation and Evacuation Procedures 2
What is the minimum recommended vacuum level (microns) before closing service valves and charging a residential AC system?