Compressor Anti-Slugging Strategy
WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
Liquid refrigerant may accumulate in the A/C compressor under certain conditions. To alleviate damage to the A/C compressor, compressor anti-slugging strategy (CASS) is used.
CASS is initiated only under specific conditions:
- the ignition is off for more than 8 hours
- the ambient temperature is above -4°C (25°F)
- battery voltage is greater than 8.5 volts during engine cranking
When these conditions are present, the powertrain control module (PCM) will activate the A/C control relay prior to engine cranking. The A/C control relay engages the A/C compressor for approximately 4-15 A/C compressor revolutions or a maximum of 2 seconds (depending upon vehicle application), allowing the liquid refrigerant to be pushed from the A/C compressor. CASS is initiated by the PCM regardless of the function selector switch position.