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Accumulator/Filter Drier Replacement

Just a few reasons an accumulator/filter drier must be replaced during compressor replacement.

The accumulator contains the desiccant bag that absorbs trace amounts of moisture entering the system. The bag must contain the correct amount and type of desiccant (XH7 or XH9). Trace moisture can lead to the formation of corrosive acids and cause freeze ups in the system. If the desiccant bag is not properly secured to the “J” tube it can wear through and release the desiccant material and contaminate the entire system. 

  • Dirty oil from the original failed compressor can be trapped in the bottom of the accumulator. This oil will contain fine, abrasive particles that would rapidly ruin the new compressor if the accumulator is not replaced. Since the accumulator cannot be flushed, these contaminants cannot be removed.
  • Length of exposure to moisture cannot be determined on a system with a leak
  • The average size desiccant bag holds a maximum of a tablespoon of moisture
  • Excessive moisture may cause abnormal gauge readings, making diagnosis difficult
  • The average life span of the desiccant is about four years
  • Most manufacturers require replacement to maintain compressor warranty

Airflow and A/C Performance


Poor A/C performance after compressor replacement may not be associated with an airflow issue, especially when no obvious signs of engine overheating are evident. Therefore, a thorough evaluation of the system should be performed to avoid repeat failures and COMEBACKS following an A/C repair job.


  • Electric Fan and/or Viscous Fan Clutch Operation
    • The PCM looks at a wide range of inputs to determine when and at what speeds the radiator and condenser fans should be operated, including engine/transmission temperature, A/C head pressure, road speed, etc. Temperature pressure sensors and switches essential for fan operation are often shifted in calibration, causing delayed or even no fan operation. See GM TSB 04-06-02-005 / GM TSB 04-01-38-019A
  • Fan Shroud & Bodywork Integrity
    • Missing or damaged air dams and fan shrouds can seriously disrupt airflow through the condenser/radiator
  • Debris on Radiator/Condenser
    • Debris on the radiator in the space between it and the condenser may not be obvious and may affect condenser airflow much more severely than the radiator itself. The result can be poor HVAC performance even though there is no evidence of engine overheating.
  • Modifications
    • Custom Spoilers, Grills, Lift or Lowering Kits, Improperly Added Fans, etc.
    • These modifications can disturb normal airflow through the condenser / radiator assembly. They can also disturb normal airflow over the fan clutch thermostatic spring, which can adversely impact its operation.

Slugging of Low-Mount Compressors

Many of today’s A/C systems are designed with a low-mount compressor. These units are susceptible to “liquid slugging,” which could lead to a catastrophic compressor failure in a matter of seconds. This is caused when oil and liquid refrigerant collect in the compressor body when the system is at rest, resulting in hydraulic lock and catastrophic failure upon initial compressor engagement. Protect your investment with Four Seasons® award winning product, The Deslugger®.

Compressor Oil

When a compressor experiences a catastrophic compressor failure, it is generally the result of an underlying issue. Determining the root cause of the compressor failure is just one of the essential steps to avoid a comeback and ensure a successful repair.

Performing an “Oil Audit” may help indicate the root cause of a compressor failure. Always drain and capture as much of the old oil as possible when replacing a compressor.The amount recovered and its condition can provide important clues as to the root cause of the compressor failure. Don’t forget to record the amount recovered during refrigerant recovery if there was refrigerant in the system. Drain oil from the discharge and suction ports and also from the compressor crankcase if it has a drain plug.

  • Small amount of oil recovered: The system may have a leak which must found and repaired to avoid a repeat failure. System may have been low on refrigerant charge causing oil to drop out in the evaporator, resulting in lack of compressor lubrication and catastrophic failure.
  • Excessive amount of oil recovered: The vehicle may have been repaired earlier with oil added without the proper evaluation. It may be necessary to thoroughly flush the system and start from scratch.
  • Appears dark or burned: The compressor may have experienced overheating prior to final failure. For example if the condenser is restricted or there is a condenser airflow issue. It is highly recommended that the condenser be replaced, especially if it is a flat tube design, when replacing the compressor. Issues that might affect condenser airflow should be checked during the repair.

!*The above scenarios may not always apply. That is why it is important to make sure that if a compressor has experienced a catastrophic failure, every inch of the refrigerant path is either new or flushed before a new compressor is installed.