Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Refrigerant Circuit, Cleaning: Notes
-- Perform the preliminary work for cleaning (flushing with refrigerant R1234yf). Refer to PRELIMINARY WORK TO CLEAN REFRIGERANT CIRCUIT (FLUSHING WITH REFRIGERANT R1234YF) .
-- Check the refrigerant quantity in the A/C Service Station there must be at least 6 kg (13.23 lbs) refrigerant R1234yf present. Refer to A/C Service Station Owner's Manual.
-- Empty the A/C Service Station container for used oil. Refer to the A/C Service Station Owner's Manual.
-- Connect the supply hose (high pressure side) of A/C Service Station to the low pressure line leading to the A/C compressor (line with larger diameter) using an adapter. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .
-- Connect the return hose (low pressure or intake side) of the A/C Service Station to the output of refrigerant circuit flushing device.
-- Connect the input on the refrigerant circuit flushing device to the high pressure line leading to the A/C compressor (line with smaller diameter) using an adapter. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .
- Main Wiring Diagrams for Various Flushing Circuits. Refer to REFRIGERANT CIRCUIT, CLEANING .
- Adapter for Assembling Flushing Circuit. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .
Components are almost always flushed in the opposite refrigerant flow direction when the A/C system is in operation. (Exception: the electrically-driven A/C compressor). Refer to REFRIGERANT CIRCUIT, CLEANING .
While flushing, contaminants from the refrigerant circuit enter the refrigerant circuit flushing device and the A/C Service Station and are absorbed by the filters and dryers installed there. Depending on the contaminant, these components are to be replaced in shorter intervals according to the Owner's Manual for the A/C Service Station or refrigerant circuit flushing device. Refer to A/C Service Station Owner's Manual.
Depending on the type and degree of contamination in the flushed refrigerant circuit, the filter in the refrigerant circuit flushing device must be changed after five to ten flushing cycles (flushed vehicles) at the latest. If a heavily contaminated refrigerant circuit is flushed (the refrigerant oil from the circuit is black and viscous or there are many shavings in the refrigerant circuit), the filter should be replaced after flushing this refrigerant circuit. With a refrigerant circuit heavily contaminated in this way, it is wise to flush the refrigerant circuit again after changing the filter.
Depending on the type of contamination, dirt (old refrigerant oil and abraded material from A/C compressor) accumulates on the viewing glass of the refrigerant circuit flushing device. If necessary clean the sight glass after flushing and flush the refrigerant circuit with a flushing procedure to check (one cycle is sufficient).
Liquid refrigerant cannot be led through the expansion valve, restrictor and desiccant bag of certain receiver/dryers at the necessary speed, therefore these components must be removed and replaced by adapters if necessary. Refer to REFRIGERANT CIRCUIT, CLEANING and SYSTEM OVERVIEW - REFRIGERANT CIRCUIT (vehicle-specific Service Information).
Adapters for connecting the A/C Service Station and for bridging certain refrigerant circuit components. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.