When evacuating a residential split-system refrigerant circuit before charging, to what vacuum level should a technician pull the system to ensure moisture and non-condensables are removed?
Evacuation And Charging
Question · Easy
Which instrument must be used to accurately confirm that a system has reached a deep vacuum during evacuation?
After evacuating a new installation, a technician closes the valve to the vacuum pump and watches the micron gauge. The reading rises and stabilizes at about 1,200 microns. What does this decay test most likely indicate?
Question · Hard
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Which charging method is preferred for a new installation when the manufacturer publishes the exact factory charge plus a per-foot adjustment for line-set length?
Question · Medium
A condensing unit ships with a factory charge sufficient for 15 feet of line set. The actual installation uses a 40-foot line set, and the manufacturer specifies adding 0.6 oz of R-410A per foot beyond 15 feet. How much additional refrigerant must be weighed in?
Why must a technician flow dry nitrogen through copper tubing while brazing refrigerant joints during installation?
Refrigerant Line Installation
When routing the refrigerant line set, which line is normally insulated?
What is the correct tool sequence when preparing copper tubing for a refrigerant joint?
A technician needs to join two pieces of copper tubing without a coupling fitting. Which tubing-preparation technique enlarges one tube end so the other slips inside it?
A flare connection on a line set is leaking refrigerant after startup. What is the most likely installation cause?
Per most manufacturer instructions, when a condensing unit is mounted on the ground, the unit pad should be positioned so that the unit is:
Installing Condensing Unit
When installing an indoor coil and air handler above a finished living space, what installation feature is required to protect against water damage from condensate overflow?
Installing Indoor Equipment
Why is a properly sized trap installed in the condensate drain line of a draw-through (negative-pressure) air handler?
A thermostatic expansion valve (TXV) is being installed on a new evaporator coil. Where should the sensing bulb be mounted for accurate operation?
On a standard residential split system, how many low-voltage thermostat wires are typically required to control cooling, the indoor blower, and 24V power?
Field Wiring
In standard residential HVAC thermostat wiring color conventions, which terminal energizes the cooling (compressor contactor) circuit?
A condensing unit nameplate lists a Minimum Circuit Ampacity (MCA) of 22.5 A and a Maximum Overcurrent Protection (MOCP) of 35 A. Which conductor and breaker combination is correct?
When connecting line-voltage power to an outdoor condensing unit, what is required within sight of and readily accessible at the unit?
Which ACCA manual is used to perform the residential heating and cooling load calculation that establishes how much capacity a home requires?
Applied Knowledge Design
After completing a Manual J load, which ACCA procedure is used to select the specific air-conditioning equipment using manufacturer performance data?
Oversizing a residential air conditioner relative to the Manual J load most commonly causes which comfort problem?
What is the nominal cooling capacity in BTU/h of one ton of air conditioning?
The NATE Air Conditioning Installation exam limits system sizes to what maximum cooling capacity?
Which ACCA manual provides the procedure to design the residential duct system, including branch sizing and friction rate?
On the basic refrigeration cycle, which four major components must every installed air conditioning system contain?
System Components
In the refrigeration cycle, where does the metering device (TXV or fixed orifice) sit relative to the evaporator?
Which refrigerant is most commonly factory-charged in residential split-system air conditioners installed in recent years?
Because R-410A operates at significantly higher pressures than R-22, what type of compressor lubricant is used and must be kept from prolonged air exposure during installation?
What is the primary function of the filter-drier installed in the liquid line of a new air-conditioning system?
A scroll compressor draws normal current but produces unusually loud noise and provides little cooling immediately after a three-phase installation. What is the most likely cause?
A condenser fan motor and a compressor on a single-phase unit share which component that provides a phase shift to the start/run windings?
What is the role of the contactor in the outdoor condensing unit?
A variable-speed ECM blower motor used in a new air handler must be set up during installation by:
Which indoor coil configuration is shaped like the letter 'A' and is commonly installed on top of an upflow furnace?
A back-seated service valve at the outdoor unit, with the stem turned fully counterclockwise, accomplishes what?
What is the purpose of an accumulator when present on the suction line of an installed system?
On a split system, the line set connects which two pieces of equipment?
A packaged air-conditioning unit differs from a split system in that:
Which device is installed to protect the compressor windings against excessive current draw or overheating?
Why is a crankcase heater used on some installed condensing units, especially in cold climates?
Which duct system layout uses a single large trunk that maintains a constant cross-sectional area with branch runs taking off along its length?
Duct Installation
Per SMACNA and code, what is the correct way to seal joints and seams on installed sheet-metal ductwork?
When installing flexible duct, which practice prevents excessive airflow restriction?
Why is ductwork routed through unconditioned spaces such as attics required to be insulated?
A Pittsburgh seam and snap-lock seam are examples of:
What is the function of a balancing damper installed in a branch duct run?
Which ventilation standard establishes minimum whole-house mechanical ventilation rates that may be addressed during a residential AC installation?
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