Which condition can contribute to excessive high-side pressure in a self-contained recovery device?

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Excess non-condensables in the recovery tank raise the high-side pressure because air or other gases don’t condense with the refrigerant. They occupy space that should be filled by condensed liquid, making condensation less efficient and keeping more vapor in the system. As the condenser works to remove heat, the presence of these non-condensables hinders heat transfer, so the refrigerant remains in a vapor state at higher pressure. The compressor then has to push against this higher head pressure, increasing the high-side pressure in the system. In contrast, simply closing an inlet or an outlet valve stops flow and doesn’t introduce non-condensables or directly cause elevated high-side pressure. A faulty compressor could cause various issues but isn’t the direct cause of high-side pressure from non-condensables. Purging or removing the non-condensables helps bring the high-side pressure back down.