Flushing the car AC system - The methods
Here you will find useful tips and information for flushing the air-conditioning system in vehicles.
Important safety note
The following technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for use by suitably qualified personnel only.
Flushing air-conditioning systems is extremely important when repairs are carried out or if a compressor is damaged. The flushing process removes impurities and harmful substances from the air-conditioning circuit.
Flushing is necessary whenever professional repairs are carried out, as well as to prevent the need for further expensive repairs at a later date. In addition, flushing protects the warranty in the event of claims against the supplier and guarantees customer satisfaction.
However, do not flush compressors, expansion/throttle valves, or filter dryers and/or accumulators. Use adapters to bridge these components during the flushing process. Once the flushing process is complete, the valves and filters must be replaced.
With its integrated flushing function, the air-conditioning service unit enables quick and cost-effective flushing of air-conditioning systems using liquid refrigerant R134a. An external flushing device and parts from a flushing adapter set must be used for this – both are available separately. Once the function has been started on the device, the vehicle air-conditioning system is filled with liquid refrigerant and then vacuumed again. This cycle should be carried out three times to achieve maximum cleaning effect.
In this method, the air-conditioning system is cleaned with a special flushing liquid (in combination with compressed air). After the flushing process, the system must be dried with nitrogen. This method is especially well suited for converting from R12 to R134a and is compatible with R1234yf air-conditioning systems. Even with the expensive R1234yf air-conditioning refrigerant, chemical flushing is a cost-effective alternative.
Note: Nitrogen must be used to dry the system after flushing with the flushing liquid.
Here, the connecting pipes and system components are blown out individually using nitrogen. When blowing out, it must be ensured that the maximum pressure of 12 bar is not exceeded.
What contaminants can be removed by flushing? What are the consequences of these types of contamination?