Refrigerant Circuit, Cleaning (Flushing) With Refrigerant R134A: Flushing

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2018 Audi S6, 2018 Audi A6 Quattro, 2018 Audi A6, 2017 Audi S6, and 2017 Audi A6 Quattro. However, it is still accessible from the selected car via links, so may be relevant.

-- Check the refrigerant quantity in the A/C service station. There must be at least 6 kg of refrigerant R134a.

NOTE:

If necessary, turn on the heating installed in the A/C service station for the refrigerant cylinder before the first flushing procedure (to increase the pressure in the refrigerant cylinder) and turn it off before the first extraction during the flushing procedure.

-- Drain the used oil container of the A/C service station.

-- 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 the 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 .

NOTE:

Components are always (with the exception of the electric A/C compressor) flushed in the opposite direction of refrigerant flow when the A/C system is operating. Refer to FLUSHING CIRCUIT BLOCK DIAGRAMS .

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 in line with operating instructions for A/C service station or refrigerant circuit flushing device.

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. Clean the viewing glass after flushing if necessary, and flush the refrigerant circuit once more with one flushing procedure as a check (one cycle is sufficient).

Liquid refrigerant cannot be channeled 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.

Adapters for connecting the A/C service station and for bridging certain refrigerant circuit components. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

-- Depending on the refrigerant circuit, assemble the flushing circuit in the vehicle. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

Vehicles with Two Evaporators in Refrigerant Circuit:

NOTE:

The refrigerant circuit is cleaned in two flushing cycles (first the section with the evaporator in the front heater and A/C unit and then the section with the evaporator in the rear heater and A/C unit. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

For vehicles with two evaporators, the circuit to the second evaporator must be disconnected from the circuit of the first evaporator and must be flushed in a separate work procedure. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT

Vehicles with High-Voltage System (without Additional A/C System Functions, for Example the Audi A3 e-tron, Audi Q5 hybrid etc.)

NOTE:

The refrigerant circuit is cleaned in two flushing cycles (first the section with the evaporator in the front heater and A/C unit and then the section with the high-voltage battery heat exchanger or the evaporator in the battery cooling module). Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

For vehicles with two evaporators or an evaporator with a heat exchanger, disconnect the circuit to the second evaporator or to the heat exchanger from the circuit for the first evaporator using the manual shut-off valves and flush it in a separate work procedure. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT .

A flushing cycle currently consists of three flushing procedures one after the other (depending on the program in the respective A/C service station). Refer to REFRIGERANT CIRCUIT, CLEANING (FLUSHING) WITH REFRIGERANT R134A .

-- If necessary, close or open the installed manual shut-off valves depending on which section of the refrigerant circuit should be flushed during this flushing cycle.

Vehicles with High-Voltage System (with Additional A/C System Functions, such as Heat Pump Operation on Audi Q7 e-tron, for Example)

NOTE:

The refrigerant circuit is cleaned in multiple flushing cycles. Refer to ADAPTER FOR ASSEMBLING FLUSHING CIRCUIT and (Cleaning the A/C system refrigerant circuit).

To flush, the circuit is divided into multiple sections and then cleaned during one flushing cycle at a time. It is divided by activating the installed electrically activated valves and using the installed manual shut-off valves. (Cleaning the A/C system refrigerant circuit).

The design of the different flushing circuits for these vehicles is described in the respective vehicle-specific repair information. Refer to

-- Close or open the installed manual shut-off valves depending on which section of the refrigerant circuit should be flushed during this flushing cycle.

-- Close or open the installed power-operated valves using the designated routine in the corresponding vehicle control module depending on which section of the refrigerant circuit is to be flushed in this flushing cycle. Use the Vehicle Diagnostic Tester in the "Guided Fault Finding" function and refer to appropriate service information

All Vehicles

-- Turn on the A/C service station and flush the refrigerant circuit (duration approximately one to one and a half hours for one flushing cycle with three flushing operations).

NOTE:

Perform the flushing procedure according to operating instructions of the A/C service station. Refer to the A/C Service Station Operating Instructions.

Depending on version of A/C service station, the used oil container only holds approximately 125 cm ³ of refrigerant oil. If a system with a larger quantity of refrigerant oil must be flushed, it may be necessary to drain the used oil container after the first flushing procedure of one flushing cycle.

Observe the refrigerant that flows back into the A/C service station from the refrigerant circuit. Only when the refrigerant streams clear and completely colorless through the viewing glass on the refrigerant circuit flushing device into the A/C service station is the refrigerant circuit cleaned.

All the refrigerant oil is washed out of the refrigerant circuit during flushing (except for a very small amount in the evaporator, however this can be disregarded).

If heavily contaminated, it may be necessary to perform the flushing procedure twice (two flushing cycles with three flushing operations each).

Sequence of flushing procedure (sequence occurs automatically according to the A/C service station program)

After turning on, the flushing circuit (refrigerant circuit with connecting hoses and refrigerant circuit flushing device) is evacuated first and the refrigerant circuit is checked for leaks at the same time. Depending on the A/C service station version, manually switching to advance the program may be required. Refer to the A/C Service Station Operating Instructions.
A prescribed quantity of refrigerant (such as 5 kg) is added to the evacuated refrigerant circuit via the high pressure side of the A/C service station (in the opposite direction of normal flow when A/C system is in operation and also on the low pressure side of the vehicle refrigerant circuit), or, it is filled with so much refrigerant until the refrigerant circuit and viewing glasses on the refrigerant circuit flushing device are completely filled with fluid refrigerant (depending on version of A/C service station, it detects, for example, that refrigerant no longer flows in over a certain time period).
After the prescribed quantity of refrigerant has been filled, for example, the heater for the refrigerant circuit flushing device is turned on (only if the refrigerant is extracted in its gaseous form from the refrigerant circuit flushing device), depending on version of A/C service station and refrigerant circuit flushing device.
After the refrigerant has been extracted, the heating of the refrigerant circuit flushing device is switched off (if equipped). Depending on the version, the refrigerant circuit may be briefly evacuated again. After evacuation, the refrigerant oil extracted from the refrigerant circuit is separated by the A/C service station.
The sequence of filling refrigerant, extracting (and evacuating) is repeated twice (performed a total of three times). Refer to the A/C Service Station Operating Instructions.
After the third extraction, the flushing circuit is evacuated depending on the version of the A/C service station.

-- After the flushing procedure has ended, check the viewing glass(es) of the refrigerant circuit flushing device. If they are dirty, clean them if necessary according to the operating instructions for the refrigerant circuit flushing device or A/C service station and perform the flushing procedure once more as a test (one cycle is sufficient, duration approximately 30 minutes). Refer to the Operating Instructions for the A/C Service Station.

-- Check the pressure in the refrigerant circuit; there must be no positive pressure in the refrigerant circuit (evacuate briefly once more if necessary).

-- Disconnect the connections to the A/C service station from the vehicle refrigerant circuit (there must be no positive pressure in the refrigerant circuit).

-- Replace these vehicle-specific components (restrictor and reservoir, expansion valve and receiver/dryer or dryer cartridge in the receiver/dryer).

-- Replace the A/C compressor, depending on the complaint (refer to A/C COMPRESSOR, REMOVING AND INSTALLING , or drain the rest of the refrigerant oil from the removed A/C compressor (refer to REFRIGERANT CIRCUIT COMPONENTS, REPLACING ; replacing refrigerant circuit components) and fill with the specified amount of new refrigerant oil (refer to APPROVED REFRIGERANT OILS AND CAPACITIES ; approved refrigerant oils and capacities).

NOTE:

There is a specific prescribed amount of refrigerant oil in the replacement A/C compressor. If the vehicle has two evaporators, a certain amount of refrigerant oil must also be added to the circuit if necessary, and APPROVED REFRIGERANT OILS AND CAPACITIES (Approved Refrigerant Oils and Capacities).

If the A/C compressor is not to be replaced, the quantity of refrigerant oil in the A/C compressor must be topped off according to the prescribed capacity (pour out the refrigerant oil and refill the prescribed quantity into the A/C compressor or refrigerant circuit). Refer to REFRIGERANT CIRCUIT COMPONENTS, REPLACING (replacing refrigerant circuit components) and APPROVED REFRIGERANT OILS AND CAPACITIES (approved refrigerant oils and capacities).

-- Completely reassemble the refrigerant circuit again. Refer to REFRIGERANT CIRCUIT [For engine(s) CTUA, AED, REH, EUC, TGE, REC, YNB, PNB]

-- Evacuate and fill the refrigerant circuit according to specification. Refer to REFRIGERANT CIRCUIT, EVACUATING WITH A/C SERVICE STATION and REFRIGERANT CIRCUIT, CHARGING WITH A/C SERVICE STATION .

-- Start the A/C system according to specification. Refer to (vehicle-specific repair information) and A/C SYSTEM, OPERATING AFTER CHARGING .