The repair on a household refrigerator is finished, the system has been evacuated, and the technician is ready to put refrigerant back in. How is the correct amount determined on a capillary tube small appliance?
Correct Answer
D) By weighing in the exact amount the data plate lists, using an accurate charging scale
A capillary tube is a fixed restriction with no receiver behind it to absorb an error, so the charge in a small appliance is critical: a fraction of an ounce either way changes how the unit performs. The manufacturer settles that amount at the factory and prints it on the data plate. The only reliable way to reproduce it in the field is to weigh the refrigerant in with a scale that resolves ounces. Pressure readings, frost patterns and sight glasses are all indirect, and on a system this small they are far too coarse to land on the right number.
Why This Is the Correct Answer
Small appliances meter refrigerant through a capillary tube and hold no reserve charge, so the correct amount is a specific weight rather than a pressure to chase. That weight is on the data plate. Charging by scale reproduces the factory figure exactly, which is why every manufacturer's service literature for a sealed system gives a charge in ounces or grams rather than an operating pressure.
Why the Other Options Are Wrong
Option A: By running the unit and adding vapor until suction pressure matches a chart for the refrigerant
Suction pressure on a capillary tube system moves with box temperature and load, so matching a chart figure says nothing definite about how many ounces are inside.
Option B: By adding refrigerant until frost reaches the end of the evaporator with the door closed
Frost patterns shift with door openings, ambient temperature and how long the unit has run. Chasing frost routinely overcharges a small system by a large fraction.
Option C: By filling until the sight glass at the drier clears of bubbles at normal room temperature
Small appliances almost never have a sight glass, and on a capillary tube system a clear glass would say nothing about whether the weighed charge is right.
Memory Technique
Capillary tube means no reserve. No reserve means no guessing. Weigh it.
Reference Hint
Small appliances are critically charged. Weigh in the exact data plate charge with a scale.
More epa-608-type-1 Questions
An under-counter ice maker is one factory-sealed cabinet, while a modular ice machine head is joined to a remote condenser by field-run tubing. What certification does servicing the modular machine's circuit require?
A technician recovers refrigerant from a small appliance using a recovery machine that was manufactured in 1991. What recovery level must that older equipment achieve?
Two technicians recover from identical refrigerators with working compressors, one using a 1991 recovery machine and the other a 2015 machine. Why do their required recovery levels differ?
System-dependent recovery equipment may be used only on appliances that normally hold up to what amount of refrigerant?
What feature defines a self-contained recovery unit and sets it apart from the system-dependent kind?
When system-dependent recovery equipment is used on a small appliance whose compressor still runs, how can that working compressor be put to use?
Recovery from a small appliance has slowed down and the pressure is barely moving. What accepted technique helps drive the remaining refrigerant out?
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