General Information For Replacing Components
The receiver/dryer or desiccant bag cartridge should not be replaced under the following conditions.
- The opened refrigerant circuit was closed immediately with clean plugs for example plugs from the Engine Bung Set :VAS 6122 .
- After an accident when there is no damage on the receiver/dryer.
- The repair was done quickly (not beyond the normal repair time).
- The vehicle is not older than five years.
The receiver/dryer or dryer cartridge should be replaced under the following conditions.
- The refrigerant circuit has been opened for an indefinite period of time (slow leak).
- The receiver/dryer is damaged (accident).
- The repair exceeded the normal repair time.
- The refrigerant circuit was opened and the vehicle is older than five years.
- The refrigerant circuit is blown though with nitrogen.
- The refrigerant circuit was flushed with R1234yf.
- The A/C compressor has locked up.
- Any refrigerant circuit components submitted for quality observation must be sealed (use the original caps from the replacement part).
- Replace damaged or leaking refrigerant circuit components. Refer to COMPONENTS, REPLACING .
- Any refrigerant circuit components submitted for quality observation must be sealed (use the original caps from the replacement part).
- To date, the replacement parts A/C compressor, receiver/dryer, evaporator and condenser have been filled with nitrogen gas. This charging stops gradually or the charging pressure is so low that gas does not escape noticeably when opening.
- On vehicles installed with a compressor with no A/C clutch, the engine is only to be started following complete assembly of the refrigerant circuit (A/C compressor always in operation as well).
- When the refrigerant circuit is empty, the A/C compressor with A/C Compressor Regulator Valve -N280- (without A/C Clutch -N25-) is switched to internal lubrication with the result that only a minimal amount of oil is pumped from the compressor into the circuit.
The following replacement part (A/C compressor, reservoir, evaporator and condenser) can be filled with nitrogen gas, this filling is not always present. Therefore little or no pressure equalization is noticeable when unscrewing plugs from replacement parts.
Depending on the storage location and storage time, very little or no pressure equalization may be noticeable when first unscrewing plugs on components that were filled with nitrogen gas from the manufacturer; therefore, it is not possible to make a prediction about the presence of leaks in a component. So for example the nitrogen gas which was filled via the shaft seal from a replacement part A/C compressor can flow out over time via the shaft seal although the A/C compressor does not have any leaks.
As parts are sometimes stored for lengthy periods and at different locations within the spare parts organization, it is entirely possible that gas will escape from some parts and not from others on initial opening (even in the case of identical spare part numbers). Therefore, carefully remove the caps from the replacement part connections and allow the nitrogen gas to escape slowly.
There are one or two expansion valves and a receiver/dryer or dryer reservoir installed in the refrigerant circuit. Refer to SYSTEM OVERVIEW - REFRIGERANT CIRCUIT .
Replace the dryer cartridge or components with desiccant bag (receiver/dryer) after cleaning (flushing with refrigerant R1234yf refer to REFRIGERANT CIRCUIT, CLEANING ) the refrigerant circuit at the same time hold sealed as long as possible so that the absorption of moisture is as little as possible.
Seal open connections and pipes (to prevent absorption of moisture).
Dispose of dirty or used oils of unknown origin paying attention to local regulations.