Type II — medium, high and very high-pressure appliancesDifficulty 3/5
After reaching the required recovery vacuum, the system pressure rises again over the next few minutes. What does this indicate?
- ALiquid refrigerant remains in the system or is dissolved in the compressor oil
- BThe recovery machine has failed and its internal valves are leaking backwards
- CThe required level was exceeded and refrigerant is being drawn back into the system
- DNon-condensable gases have entered and must be purged before work can continue
Show answer and rationale
Correct: A. Refrigerant dissolved in oil boils off slowly, raising the pressure after the gauge first reaches target. This is why the topic list tells you to wait and watch rather than disconnect immediately.
- B — A machine fault would show as a failure to reach the level, not as a slow rise after it.
- C — Recovery machines do not push refrigerant back into an appliance once the level is reached.
- D — Non-condensables are a low-pressure system concern and would not appear at this point.