A/C System, Flushing With Compressed Air and Nitrogen

A/C Refrigerant System (R-134a), Flushing With Compressed Air and Nitrogen


CAUTION!
When using compressed nitrogen always use a pressure regulator and the proper adaptor hoses and fittings (available locally). During flushing, use existing exhaust/ventilation systems to draw off the gas mixture escaping from the A/C system.


- Use compressed air and nitrogen (available locally) to remove moisture, impurities and old refrigerant oil from A/C refrigerant system.
- First blow out old refrigerant oil and dirt with compressed air, then dry components with nitrogen.
- DO NOT blow compressed air and nitrogen through the compressor or restrictor.
- Always flush components in opposite direction of refrigerant flow.
- Flush evaporator through the low pressure line with the high pressure line removed.
- If any component has dark thick deposits that cannot be removed with compressed air, replace component.
- Thin light gray deposits in refrigerant lines and hoses are normal and do not impair the function of the system.
- Always replace accumulator and restrictor after flushing.

Flush refrigerant system with compressed air and nitrogen if:
- Refrigerant oil is dark and viscous (thick)
- Too much refrigerant oil is in the system following compressor replacement
- Unclear or do not know how much refrigerant oil is in the system
- Moisture, dirt or other impurities have entered the refrigerant system (i.e. following an accident)
- Unable to pull a constant vacuum during evacuation of a leak-free system due to excessive moisture in the system
- Refrigerant system has been open longer than the time required for normal repairs (i.e. following an accident)
- Based on temperature and pressure measurements, system is diagnosed with moisture contamination
- Compressor is replaced due to noises or internal damage
- Required after replacing certain components in certain situations See A/C refrigerant system, components, replacing.