General Information For Cleaning Refrigerant Circuit

• The refrigerant R744 cannot be used to clean the refrigerant circuit.
• The typical workshop A/C Service Stations cannot be used to recapture, condense, liquefy and reuse the naturally occurring refrigerant R744 from the refrigerant circuit. Therefore, it is released into the environment via a draining device on the A/C Service Station. Refer to REFRIGERANT CIRCUIT, DISCHARGING . It is also for this reason that an R744 refrigerant circuit cannot be cleaned using refrigerant R744. Additionally, the physical characteristics of the refrigerant do not permit this at an ambient temperature above approximately 31 °C (87.8 °F) (critical temperature). Refer to REFRIGERANT PRESSURE AND BOILING POINT . Therefore, the R744 refrigerant circuit is cleaned (flushed) using refrigerant R1234yf or refrigerant R134a).
• Refrigerant R134a or refrigerant R1234yf may be used, since little or no refrigerant can vent into the air when cleaning the refrigerant circuit. When handling these refrigerants, observe the safety precautions in the Service Informations for vehicles that have refrigerant circuits filled with either R1234yf or R134a. Refer to Working with A/C Service Station (1 Of 2) / Working with A/C Service Station (2 Of 2) and the appropriate service information .
• All information for refrigerants R134a and R1234yf can be found in the respective Service Informations. Refer to Working with A/C Service Station (1 Of 2) / Working with A/C Service Station (2 Of 2) and the appropriate service information .
• If it is suspected that chemicals to seal leaks (leak stop additives) were added to the refrigerant circuit that is to be flushed, do not connect the A/C Service Station and do not flush this refrigerant circuit.
• Chemical substances used to seal leaks (leak stop additives) form deposits in the refrigerant circuit, which affect the A/C system function and cause the A/C system (and its A/C Service Station) to malfunction.
• Inform the customer that there are substances in the A/C system that are not approved by Volkswagen/Audi and for this reason the A/C system cannot be flushed or serviced.
• Volkswagen/Audi does not approve the use of chemicals to seal leaks in the refrigerant circuit (leak stop additives).
• It is generally not possible to externally recognize chemical substances to seal leaks in the refrigerant circuit (leak stop additive), and the stickers that are supposed to come with them are usually not there. Therefore be careful when working with a vehicle if its service history is unknown.

• The refrigerant circuit must be cleaned by flushing with refrigerant R1234yf or R134a in order to remove moisture, contaminants (such as abraded material from a faulty A/C compressor) as well as old refrigerant oil as cleanly and efficiently as possible, without wasting refrigerant, without the need for extensive assembly work and without endangering the environment.

Clean (flush) the refrigerant circuit with refrigerant R1234yf or R134a:

-- If dirt or other contaminants are in the circuit.

-- The refrigerant circuit has been left open for longer than normal (for example, after a collision).

-- Pressure and temperature measurements in the circuit indicate that there is moisture in the refrigerant circuit.

-- If there is any uncertainty as to how much refrigerant oil is in the refrigerant circuit.

-- A/C compressor had to be replaced due to internal damage (for example, noise or no output). Refer to COMPONENTS, REPLACING .

-- If it is stipulated by the vehicle-specific Service Information following the replacement of certain components.