A window unit's data plate lists a ten ounce charge, the compressor ran throughout the job, the recovery machine was built in 2015, and nine ounces now sit in the recovery cylinder. What does that result mean?
- The ninety percent requirement is satisfied, so the sealed circuit may now be opened
- BOnly eighty percent applies with a running compressor, so an extra ounce came out needlessly
Eighty percent is the figure for a newer machine working on an appliance whose compressor will not run. Swapping the two conditions is the single most common mistake on this rule.
- CThe result falls short, because a running compressor raises the target to the entire charge
No branch of the small appliance rule asks for the entire charge. The requirement tops out at ninety percent precisely because the compressor oil holds some refrigerant back.
- DThe reading cannot count, because recovered weight is never used to judge the requirement
Weighing what comes out against the factory charge is exactly how the percentage routes are demonstrated. The alternative to weighing is the vacuum reading, not a ban on the scale.
Why A is correct
Two facts set the level here: the recovery machine was built after November 15, 1993, and the appliance compressor ran. That pair puts the job in the ninety percent branch. Nine ounces recovered against a ten ounce factory charge lands exactly on that figure, so the requirement is satisfied and there is no reason to keep the machine running before opening the system.
What this question is testing
This item tests whether you can apply both halves of the newer equipment rule to a concrete job and then judge a result against the figure you selected. It also checks that you do not confuse the ninety percent and eighty percent conditions, which is where most candidates lose this point.
On the job
Techs who use the percentage route keep a small platform scale in the van and set the recovery cylinder on it before the first hose goes on. Tare the cylinder, run the job, read the gain. On a ten ounce window unit the whole recovery is a matter of ounces, so the scale has to be one that resolves them; a bathroom scale will not. Most technicians skip the arithmetic altogether by taking the vacuum route, but on a job where the cylinder is already on the scale for other reasons, reading the gain is the faster proof.
Memory technique
Running compressor, higher bar. The unit that helps you is the unit that is held to more.
Exam tip
Read the equipment date first, then the compressor condition, then do the arithmetic. Two of the wrong choices here are built from swapping those two conditions.
Where to look it up
Newer recovery equipment: ninety percent with the compressor running, eighty percent with it not running.