A system has been open to the atmosphere for two days before its repair was completed. Beyond slowing the equipment down, what does moisture left in a running refrigeration system cause?
Correct Answer
B) Acid formation in the oil and ice blocking the metering device
Water in a system does two things at once. Circulating with refrigerant and oil at compressor discharge temperatures it breaks down into acids that attack motor windings and plate copper onto steel surfaces. At the metering device, where the refrigerant drops in pressure and temperature, free water freezes and blocks flow, so the system starves and then clears in a cycle that looks like an intermittent charge problem. Neither effect goes away on its own.
Why This Is the Correct Answer
Moisture reacts with the refrigerant and the oil at the temperatures found at the compressor discharge, producing acids that degrade motor insulation and cause copper plating on wear surfaces. At the same time, free water reaching the expansion valve or capillary tube freezes at the point where the pressure drops and blocks refrigerant flow. Long evacuation and a fresh filter drier are what prevent both.
Why the Other Options Are Wrong
Option A: A permanent rise in the boiling point of the refrigerant charge
The refrigerant's boiling point is a property of the refrigerant. Moisture contaminates the charge and forms acid, but it does not permanently alter that property.
Option C: Separation of the refrigerant charge into its individual components
Separation into components is what happens to a zeotropic blend when vapor is drawn off it. Moisture in the system is a different problem entirely.
Option D: A gradual loss of charge through the elastomer seals and gaskets
Elastomer seals are not attacked in a way that vents charge. The damage moisture does is to the oil, the metering device and the motor windings.
Memory Technique
Hot end makes acid, cold end makes ice. Water ruins both ends of the same system.
Reference Hint
Moisture in a system forms acids with the oil and refrigerant and freezes at the metering device.
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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