Exam Question

### (a) Ingress of Air into the Freon System
**Causes:**
* **Operation in a Vacuum:** The primary cause is a leak on the low-pressure side of the system (e.g., compressor suction line, shaft seal, or evaporator) when operating pressures fall below atmospheric. This creates a pressure differential that draws air and moisture into the system.
* **Improper Maintenance:** Failure to properly purge charging lines with refrigerant before connecting them to the system. Insufficient evacuation (pulling a vacuum) after the system has been opened for repair allows residual air to remain.