Installation and Service Procedures Flashcards
7 cards from real Air Conditioning Repair practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Installation and Service Procedures flashcards as text
A technician is performing a standing vacuum test and the micron gauge rises from 300 to 500 microns over 10 minutes after isolating the pump. What does this indicate?
Answer: Moisture is present in the system
A vacuum that rises and levels off (rather than continuing to rise to atmospheric) indicates moisture boiling off in the vacuum — the system needs continued evacuation.
What is the recommended method for testing a newly brazed joint for leaks before evacuating and charging a system?
Answer: Pressurize with nitrogen and use electronic leak detector or soap bubbles
Nitrogen pressure testing with an electronic detector or soap bubbles is safe and code-compliant; using refrigerant for leak testing wastes refrigerant and is prohibited.
On a cooling system with a TXV, the technician measures 12°F subcooling at the condensing unit outlet and 22°F subcooling at the indoor unit inlet. What does this indicate?
Answer: There is a restriction in the liquid line
A significant subcooling rise through the liquid line indicates a restriction (such as a clogged filter drier or kinked line) that is causing a pressure and temperature drop.
When pulling a vacuum on an R-410A system, the target micron level before charging should be:
Answer: 500 microns
Industry best practice (ACCA, ASHRAE) targets 500 microns or below before charging; this level ensures adequate moisture and non-condensable gas removal.
A residential split system is being installed in a garage. What special consideration applies to the condensing unit's electrical disconnect?
Answer: A fused disconnect must be within sight of and readily accessible from the unit
NEC 440.14 requires a disconnect within sight of and readily accessible from the condensing unit to allow safe service lockout.
When installing refrigerant line sets, which practice is most important to prevent future service problems?
Answer: Document the line set route and leave accessible service ports
Documenting the line route and ensuring accessible service ports allows future technicians to diagnose and repair the system without damaging walls or ceilings.
A new heat pump installation requires the thermostat wire to run 120 feet from the air handler to the thermostat. What adjustment may be necessary?
Answer: Use 18-gauge wire instead of 20-gauge to reduce voltage drop
Long thermostat wire runs can experience voltage drop that prevents controls from operating reliably; heavier 18-gauge wire reduces resistance over the longer distance.