A shop wants its recovery machines to keep pulling refrigerant at full speed and to stay leak tight between jobs. What routine care actually supports those goals?
- AStoring each machine with its hoses uncapped so any trapped refrigerant can work its way out between jobs
Uncapped hoses let trapped refrigerant escape, which is a release, and they draw moist air into the machine for the next job. Hoses are capped precisely to prevent both.
- BRunning each machine dry for an hour every week to drive off any moisture inside it in the shop
Running a recovery compressor with no refrigerant to cool and lubricate it shortens its life. Moisture is handled by filter driers and proper evacuation, not by running the machine dry.
- CReplacing the machine oil with automotive engine oil, which stands up to heat better in summer
Recovery machines use the lubricant the manufacturer specifies for compatibility with the refrigerants handled. Automotive engine oil is the wrong chemistry whatever the season, and it attacks the seals and the compressor it is poured into.
- Changing filter driers on the manufacturer schedule and checking hoses, fittings and gaskets for leaks
Why D is correct
Filter driers restrict as they load up and slow recovery noticeably, while worn hoses, couplers, and gaskets leak refrigerant and admit air. Changing driers on schedule and inspecting connections keeps recovery rate up and keeps the machine from releasing refrigerant between jobs.
What this question is testing
This item checks whether the candidate can identify real preventive maintenance for recovery equipment and reject practices that would release refrigerant, admit moisture, or damage the compressor.
On the job
The most common complaint about a recovery machine is that it got slow. Nine times out of ten it is a loaded filter drier, a tired coupler, or a hose gasket that no longer seals. Techs blame the machine and shops buy new ones when a drier and a set of gaskets would have restored it. A dated maintenance sticker on each machine turns this from a guessing game into a schedule.
Memory technique
Driers and connections: one keeps flow up, the other keeps refrigerant in.
Exam tip
Maintenance answers that involve open hoses or running equipment dry are always distractors. Look for filter driers and leak inspection.
Where to look it up
Keep recovery equipment maintained and leak free; change filter driers on schedule and inspect hoses and fittings.