A semi-hermetic compressor that has been opened for valve plate work twice now shows an oil film along the seam between the head and the body. What should the technician do about that joint?
Correct Answer
C) Recover the charge, remove the head and fit a new gasket to the machined faces
A gasket that has been compressed, heated and cycled loses the ability to fill the surface irregularities it was made to fill, and once it starts passing oil it is not going to recover. Retorquing a relaxed gasket can crush it further or distort the head, and external sealant does nothing about a path that starts inside. The proper repair is to recover the charge, take the head off, clean both machined faces and fit a new gasket.
Why This Is the Correct Answer
Gaskets are a single-use sealing element. Once a joint that has been made and remade begins to pass oil, the gasket has taken a permanent set and cannot be brought back by torque. The repair is to recover the charge to the required level, separate the joint, clean the machined faces of old gasket material, and fit a new gasket to the manufacturer's torque pattern.
Why the Other Options Are Wrong
Option A: Add a bead of sealant along the outside of the seam to close the path
External sealant cannot reach a leak path that runs between two machined faces, and it makes the next disassembly harder without stopping the loss.
Option B: Retorque the bolts progressively and monitor, since gaskets relax over time
Retorquing a gasket that has already taken a set risks crushing it further or distorting the head casting, and it does not restore the seal.
Option D: Ignore it, because a semi-hermetic compressor is expected to seep a little oil
Refrigeration compressors are not expected to lose oil or refrigerant in service. An oil film on a joint is evidence of a leak, not of normal operation.
Memory Technique
Gaskets get one life. When they start talking oil, they are asking to be replaced.
Reference Hint
A leaking gasketed joint is repaired by recovering the charge and fitting a new gasket, not by retorquing or sealing externally.
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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