A technician is adding R-410A to a running split system that is low on charge. What is the danger of dumping liquid refrigerant straight into the suction service valve?
Correct Answer
B) Liquid reaching the compressor suction can slug the cylinders and break valves or connecting rods, because liquid does not compress
A compressor is built to compress vapor. Liquid entering the suction port cannot be compressed, so it hammers the valve plate and can bend rods or crack valves in a single event, and it also washes oil out of the bearings over time. Because R-410A is a blend it has to leave the cylinder as liquid to keep the mixture correct, so technicians throttle that liquid slowly through a metering device or restrictor at the manifold so it flashes to vapor before reaching the compressor, or they weigh the liquid charge into the high side with the compressor off.
Why This Is the Correct Answer
Liquid is essentially incompressible. When it reaches the suction port of a running compressor, the piston tries to compress it and the mechanical energy goes into the valve plate, rods, and bearings instead. Slugging can destroy a compressor in seconds and also dilutes and washes away the oil.
Why the Other Options Are Wrong
Option A: The liquid flashes to vapor inside the charging hose, so the scale reading overstates how much refrigerant actually entered the system
Flashing in the hose does spoil the weight reading, but that is an accuracy problem the technician can correct for. What makes this practice dangerous is what the liquid does inside the compressor.
Option C: The liquid chills the suction line far enough to crack the copper tubing where it meets the service valve
Cold liquid does chill the suction line, but copper does not crack at these temperatures. The damage shows up in the compressor valve plate and rods, not out at the service valve.
Option D: The liquid collects in the condenser and drives head pressure up until the high-pressure switch trips the unit
Refrigerant entering the suction side does not pool in the condenser. An overcharge can raise head pressure, but that is a separate outcome and not the risk created by liquid at the suction port.
Memory Technique
Vapor squeezes, liquid does not. A compressor fed liquid hits a wall it cannot move.
Reference Hint
Charge blends as liquid, metered into the suction side while running, or weighed into the high side with the compressor off.
More epa-608-type-2 Questions
A walk-in cooler condensing unit holds a full charge of twenty-five pounds of R-404A, which is below the fifty pound threshold that brings an appliance under the leak repair provisions. What still applies to this unit?
An office building has thirty water source heat pumps on a common water loop, and each one left the factory assembled, hermetically sealed and charged with four pounds of R-410A. How is one of those units classified?
A data sheet for an unfamiliar refrigerant lists a boiling point of about fifty-five degrees Fahrenheit at atmospheric pressure. What does that tell a technician holding Core and Type II certification?
A technician holds Core, Type I and Type III certification and is sent to recover the charge from a twenty ton rooftop unit charged with R-410A. What does that combination of sections allow on this job?
A fleet garage technician holds only the vehicle air conditioning certification issued under Section 609 and is asked to recover the charge from the shop's own rooftop air conditioner. What does that credential allow?
A split system's outdoor unit, indoor coil and the line set the installer ran and brazed between them are being considered. For the purposes of the refrigerant rules, what makes up the appliance here?
On a new installation the line set is brazed to a factory charged outdoor unit and an indoor coil shipped under a nitrogen holding charge, with the outdoor unit's service valves still closed. What does the recovery requirement call for before that brazing?
A rooftop unit's data plate has weathered until the charge figure cannot be read, and the technician needs the full charge to place the appliance under the evacuation and leak provisions. Where should that figure come from?
A computer room air conditioning unit holds forty pounds of R-407C and connects to a remote air cooled condenser through refrigerant piping run and brazed by the installer. How is that unit classified?
A shop's office manager, who holds no technician certification, is sent to a supply house to pick up a new recovery machine for the commercial crew. What does the sales restriction require at that counter?
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