Heating & Air Conditioning Audi TT 8N

Automatic Climate Control system, On Board Diagnostic (OBD)

Note. The air conditioning control functions remain in operation during On Board Diagnostic (OBD).

Function

The A/C Control Head -E87- receives information from electrical and electronic system components (sensors), and then processes this information according to specified values.

The output signals from the control unit then activate the relevant electrical components (actuators).

To determine the cause of a malfunction or open circuit quickly, the A/C Control Head -E87- is equipped with a Diagnostic Trouble Code (DTC) memory which can be checked using the VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System or VAG 1552 mobile Scan Tool (ST).

If malfunctions occur in the monitored sensors or components, they are stored as DTCs in DTC memory together with an indication of the malfunction type.

On Board Diagnostic (OBD) must always be performed before commencing troubleshooting. Stored information must be checked using the VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System or VAG 1552 mobile scan tool.

The displayed malfunction information can be checked against the DTC table, which indicates possible malfunction causes and enables appropriate repair measures to be taken.

Notes on repairing malfunctions

1. Data output is only possible if the ignition is switched on or if the engine is running at a speed of less than 3000 RPM. At higher engine speeds, data output is restricted or aborted. For example, the output Diagnostic Test Mode (DTM) is only possible at engine speeds of up to 3000 RPM, and the On Board Diagnostic (OBD) program is aborted if this speed is exceeded).
2. If a malfunction exists for more than a predetermined period, the DTC is stored as a static malfunction. If the malfunction is no longer detected for another predetermined period of time, it is re-classified as a sporadic malfunction. This process is continuously repeated. Sporadic malfunctions are identified by "/SP," which appears at the right of the display.
3. If a sporadic malfunction does not occur for a predetermined period, it is automatically erased.

On Board Diagnostic (OBD) is only possible using VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System or VAG 1552 mobile Scan Tool (ST) ("Rapid data transfer" operating mode 1).

On Board Diagnostic (OBD) is not restricted to storing and checking Diagnostic Trouble Codes (DTC), erasing and Output Diagnostic Test Mode (Output DTM). It also has basic setting, control unit identification and coding functions.

"Blink code output" operating mode 2 is not available for the heating and air conditioning electronics.

"Self test" operating mode 3 and "Dealership code" operating mode 4 only concern the VAG 1551 and VAG 1552 scan tools and are described in the relevant operating instructions.

Available On Board Diagnostic (OBD) functions. Refer to On Board Diagnostic (OBD) technical data .

Note. This article describes On Board Diagnostic (OBD) using the VAG 1551 Scan Tool (ST). OBD can be performed in the same way using the VAG 1552 mobile Scan Tool (ST). Before DTC memory is checked and erased, it is advisable to connect the VAG 1551 or VAS 5051 and print out the existing DTCs so that a record of any malfunction is available at a later stage. (The VAG1552 does not have a printer.)

On Board Diagnostic (OBD) technical data

Note. Installation locations of components. Refer to A/C system control and regulation components in engine compartment and rear body and A/C system control and regulation components in passenger compartment . If a newly installed the A/C Control Head -E87- has not been coded or an invalid code has been entered in the A/C Control Head -E87-, the coding "00001" will be stored. If a new A/C Control Head -E87- is installed, and its display panel flashes (for about 2 minutes) when the ignition is switched on, code the A/C Control Head -E87- (function 07) and perform basic setting (function 04). While the On Board Diagnostic (OBD) is performed, the control functions of the air conditioner remain in operation and are not switched off (i.e. the compressor, positioning motors, coolant fan etc. can be activated). When the OBD is started, the control functions of the air conditioner are not interrupted. However, they are switched off if the output diagnostic test mode or basic setting functions are selected. If other diagnostic functions are selected, the air conditioning remains fully functional. The A/C Control Head -E87- is no longer connected to terminal 30 of the electrical system; it stores its latest setting when the ignition is switched off, and then reactivates it when the ignition is switched on again. The time which has elapsed since the ignition was switched off is calculated by the A/C Control Head -E87- when the ignition is switched back on (time signal supplied by instrument cluster). If more than 4 hours pass after the ignition is switched off, the current measured values from the outside air temperature sensors are used to represent the current ambient temperature and engine temperature for the purposes of regulating the system. If the "standing time" was less than 4 hours, the current values are calculated by the A/C Control Head -E87- (the heat emitted from the engine and radiator causes incorrect measurements, and therefore the current measured values from the temperature sensors are suppressed for a predefined time). The lower of the two values from the outside air temperature sensors is used for air conditioning regulation and for the external temperature display. When the convertible top is opened on Audi TT Roadsters, A/C regulation is altered. Instead of using the measured value from instrument panel interior temperature sensor -G56-, the system assumes pre-programmed outlet temperature values based on the current outside temperature. -E87- receives this information via terminal 5 in connector C from convertible top control module -J256-.

On Board Diagnostic (OBD), test requirements

1. All fuses OK per wiring diagram.
2. Battery voltage OK.
3. For testing, ignition must be switched on or the engine running (engine speed less than 3000 rpm).

Scan Tool (ST) and test equipment safety precautions

Model specific WARNINGS continued. Refer to Scan Tool (ST) and test equipment safety precautions, continued .

Scan Tool (ST) and test equipment safety precautions, continued

VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions

Requirements

1. All fuses OK per wiring diagram
2. Battery positive voltage (B+) OK
3. Ignition off

Scheme 1

1. Connect tester with adapter cable to Data Link Connector (DLC), located under instrument panel to left of steering wheel.

1. VAS 5051/1552: Use adapter cable VAS 5051/1
2. VAG 1551: Use adapter cable VAG 1551/3

Note. If test equipment is to be used during a road test. Refer to Scan Tool (ST) and test equipment safety precautions . The following description only covers the procedure for performing OBD VAG 1551 Scan Tool. If using VAS 5051 or VAG 1552, follow the operating instructions supplied with the equipment.

Indicated on display1)

1) Operating modes 1 and 2 are displayed alternately

Note. If nothing appears on the display of the VAG 1551 Scan Tool (ST), check the Data Link Connector (DLC) wiring.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

1. Additional operating information can be displayed by pressing the HELP button on the VAG 1551 scan tool.
2. The --> button is used to advance through the program sequence.
3. The PRINT button is used to switch on the printer (the indicator lamp in the button lights up).
4. DTC memory cannot be erased until it has been checked.

1. Switch ignition on and/or start engine (engine speed less than 3000 RPM).
2. Switch on compressor (press AUTO button on A/C Control Head -E87-).
3. Press button -1- to select "Rapid data transfer" operating mode 1.

Note. To check the speed signal (in "Read Measuring Value Block" function 08), move the vehicle a few meters (or yards) at walking speed before starting the OBD program.

Indicated on display

1. Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

After a short delay, the control module identification (version), coding and dealership number (where the control module was coded) are displayed ("Klimavollautomat" = fully automatic air conditioner).

Control module identification and application (depending on the vehicle equipment and coding).

Note. As a running change in production, A/C control heads -E87- with part numbers including index letters "A" and onward may be installed. These units differ from previous ones (without index letter) as follows

1. On vehicles equipped with immobilizer, allocation of ignition key is recognized (transmitted by instrument cluster) and is displayed in read measuring value block, display group 009. Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) . Also see «96 LIGHTS, SWITCHES - INTERIOR, ANTI-THEFT»(/audi/tt/8n-1998-2003/remont/cruise-control-systems/#electrical-equipment) .
2. The last four compressor cut-out conditions in effect for more than 20 seconds are stored and displayed in read measuring value block, display group 011. Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) .

Coding table

Coding example

Note. A/C Control Head -E87- with part number suffix "A" are installed as a running change during m.y. 2000. -E87- with suffix "A" differs from non suffix version as follows

1. Allocation of ignition key is recognized (as transmitted from the instrument cluster) and displayed in Read Measuring Value Block "009". Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) and «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/cruise-control-systems/#electrical-equipment)

1. The last 4 compressor cut-out conditions that are valid for longer than 20 seconds are saved in memory and displayed in Read Measuring Value Block 011. Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) .

1. WSC ZZZZZ is the dealership number of the VAG 1551 scan tool last used to perform the coding procedure.
2. DXX is the software version installed in the A/C Control Head -E87-. It is irrelevant for the purposes of dealership repairs.
3. Coding A/C Control Head -E87-. Refer to «Control Module, coding (function 07)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__control-module-coding-function-07) .

Only the functions listed above can be used for the "AC/Heating Electronics" OBD program.

1. Press --> button.

Indicated on display

Note. A list of the possible functions is printed out after pressing the HELP button. After pressing the --> button, the VAG 1551 returns to the starting position.

If one of the following DTC messages is displayed

Indicated on display

or

Indicated on display

1. Press HELP button to print out list of possible causes.
2. Check wiring to Data Link Connector (DLC) according to wiring diagram. Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

If this display appears at the beginning of or during the OBD program, malfunctions have occurred and data transfer is no longer possible between the VAG 1551 Scan Tool (ST) and the A/C Control Head -E87-.

1. Check wiring to DLC.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

1. After repairing possible causes of the malfunction, press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08.
2. Press -Q- button to confirm input.

Indicated on display

The control module identification (version), coding and dealership number (where the control module was coded) are displayed ("Klimavollautomat" = fully automatic air conditioner).

1. Press --> button.

Indicated on display

Diagnostic Trouble Code (DTC) Memory, checking (function 02)

1. Connect VAG 1551 Scan Tool (ST). Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08 and advance program until "Select function XX" appears on display. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
3. Switch printer on by pressing PRINT button (indicator lamp in button comes on).

Indicated on display (function selection)

1. Press buttons -0- and -2- to select "Check DTC Memory" function 02.

Indicated on display

1. Press -Q- button to confirm input.

Number of stored DTCs is displayed

1. Press --> button.

If "No DTC recognized" is displayed, the program returns to the starting position after --> button is pressed.

1. Press --> button.

Stored DTCs are displayed and printed sequentially.

When the last DTC has been displayed and printed out, the malfunction must be repaired using DTC table. Refer to Diagnostic Trouble Code (DTC) table .

The program returns to its starting position when the --> button is pressed. (The same applies when the message "No DTC recognized" is displayed.)

Indicated on display

1. End output (function 06). Refer to «Diagnostic Trouble Code (DTC) Memory, erasing and End Output (functions 05 and 06)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__diagnostic-trouble-code-dtc-memory-erasing) .
2. Switch ignition off and disconnect Data Link Connector (DLC).

If a DTC was recognized

1. Repair malfunction.
2. Check DTC memory (function 02).
3. Erase DTC memory (function 05).
4. Check control module versions (function 01) or code control module (function 07), respectively.

1. Perform basic setting (function 04).
2. Check DTC memory (function 02) and erase DTC memory (function 05), if necessary.
3. End output (function 06).

If no DTCs have been recognized, but the air conditioning is not working properly (e.g. the compressor is not functioning or only functioning for certain periods of time, there is unsatisfactory regulation of the system or the fresh air blower speed cannot be controlled)

1. Read measuring value block (function 08). Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) .
2. Perform output Diagnostic Test Mode (DTM) (function 03). Refer to «Output Diagnostic Test Mode (DTM) (function 03)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__output-diagnostic-test-mode-dtm-function) .
3. Check A/C cooling performance. Refer to «A/C cooling performance, testing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-cooling-performance-testing) .

Note. If no signal for the "ignition off" period is detected by the A/C Control Head -E87- when the ignition is switched on, -E87- assumes that the vehicle has been left standing for more than 4 hours, and the engine temperature is assumed to be identical to the ambient temperature. If the system is in heating mode, there may be a delay before the fresh air blower switches on, even though the engine is warm. Refer to Read Measuring Value Block (function 08) . The outside air temperature display -G106- in the instrument cluster may also display incorrect ambient temperature values. If the illumination of the A/C Control Head -E87- does not light up when the ignition is switched on, restore the voltage supply to -E87- from terminals 88, 58d and 58s (dimming) Read Measuring Value Block: Refer to Read Measuring Value Block (function 08) , A/C Control Head -E87-, electrical testing and Electrical Wiring Diagrams, Troubleshooting & Component Locations.

Diagnostic Trouble Code (DTC) table

Note. The tables below provide a summary of all the DTCs which can be detected by the A/C Control Head -E87- and displayed on the VAG 1551 Scan Tool (ST). The DTCs are listed according to their 5-digit numbers. If malfunctions occur only occasionally or if DTC memory was not erased after repairs, these DTCs are displayed as "sporadic." The contents of DTC memory are retained until erased (permanent memory). DTCs and blink codes (only in the case of individual components) appear only in the printout in operating mode -1- "Rapid data transfer."

Note. The malfunction type may also appear in the DTC table below the relevant component. After repairs, DTC memory must always be checked again and erased using the VAG 1551 Scan Tool (ST). Before replacing components, always check the relevant positive and Ground (GND) connections (terminals 15, 75, 30 and 31), as well as all harness connectors (between the A/C Control Head -E87- and the component indicated as being faulty) according to the wiring diagram. When dealing with any sporadic DTCs, always pay attention to possible loose terminals in harness connectors. After replacing a component of the heating and air conditioning system, always perform basic setting (function 04) and then check and erase DTC memory (functions 02 and 05). Use the VAG 1598/11 adapter and VAG 1598/12 adapter to test the electrical connections of the A/C Control Head -E87- according to the wiring diagram. If the A/C Control Head -E87- remains in operation after switching the ignition off, test the wiring to the A/C Control Head-E87- (connector D, terminal 1) for a short circuit to B+ according to the wiring diagram. If a malfunction is detected in the potentiometer of one of the air distribution positioning motors, the air distribution can be changed by pressing the buttons on the A/C Control Head -E87-. When the convertible top is opened on Audi TT Roadsters, A/C regulation is altered. Instead of using the measured value from instrument panel interior temperature sensor -G56-, the system assumes pre-programmed outlet temperature values based on the current outside temperature. -E87- receives this information via terminal 5 in connector C from convertible top control module -J256-. The display is changed from °C (Celsius) to °F (Fahrenheit) and vice-versa by pressing the "+" button on the driver's side while simultaneously holding down the recirculated air button. If problems have been reported with the heating and air conditioning system but no malfunctions can be detected, perform output Diagnostic Test Mode (DTM) function 03 and Read Measuring Value Block function 08. Testing the cooling performance of the air conditioning. Refer to A/C cooling performance, testing .

1) If -G92- malfunctions, temperature regulator flap motor -V68- can be adjusted manually by turning the temperature control knob towards "+" or "-" (display range from 0 °C to 50 °C).

2) This malfunction is only detected during basic setting.

3) Both limit stops must be reached.

Vehicles with A/C Pressure Switch -F129

Note. As a running change in production, pressure switch -F129 is replaced by high pressure sensor -G65-. The function of Coolant Fan Control (FC) Module -J293 and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129 or high pressure sensor -G65-.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

1. A/C pressure switch -F129- is comprised of 2 switches: the compressor is deactivated via terminals 1 and 2 if the pressure in the refrigerant circuit is too high or too low (switch opens), and the coolant fan is switched to second speed via terminals 3 and 4 (switch closes).
2. If the switch between terminals 1 and 2 in A/C pressure switch -F129- opens, the A/C Control Head -E87- initially assumes there is excess pressure in the refrigerant circuit and stores this condition as a malfunction. If the measured ambient temperature is between 0 °C (32 °F) and 50 °C (122 °F) and the switch remains open for longer than 30 seconds, the system switches from excess pressure to low pressure (low pressure switch function) Read Measuring Value Block: Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) (display group 001, compressor cut-off conditions).
3. If A/C pressure switch -F129- registers as "high pressure switch open" 30 times during a driving cycle (e.g. because of a loose connection), the compressor is switched off. The compressor can be switched on again by pressing the "Compressor on" button, or by switching the ignition off and on again. If this malfunction occurs over several driving cycles, the compressor cannot be switched on again unless DTC memory has been erased.

Vehicles with high pressure sensor -G65

Note. As a running change in production, pressure switch -F129 is replaced by high pressure sensor -G65-. The function of radiator fan control unit -J293 and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129 or high pressure sensor -G65-.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

1. High pressure sensor -G65- transmits a square wave signal at a rate which varies according to the refrigerant system pressure. Checking signal. Refer to «High pressure sensor -G65- signal, checking»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Coolant Fan Control (FC) Module -J293 reacts to the pulse rate of the signal from high pressure sensor -G65 as follows: 1) It informs the A/C Control Head -E87- that the pressure in the refrigerant system is OK and that A/C clutch -N25- can be switched on (compressor is switched on via -J293-. 2) If the refrigerant system pressure rises, the control unit switches the radiator fan to speed 2.
3. The signal generated by high pressure sensor -G65- is also provided as an input to the Motronic Engine Control Module (ECM). As the amount of torque needed to drive the A/C compressor varies according to the refrigerant system pressure, the ECM processes this signal in order to enhance engine performance. Depending on the type of ECM, this signal may or may not appear as a duty cycle on the read measuring value block display (function 08). Refer to «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-amu) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-atc) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): ATC «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276272-S12227258552008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AWP «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276273-S13756956692008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): BEA .
4. If excessive refrigerant system pressure is detected 30 times during a driving cycle and A/C Control Head -E87 switches off the A/C clutch -N25, the compressor will not come on again automatically. The compressor can be switched on again by pressing the "Compressor on" button or by switching the ignition off and on again. If this occurs over several driving cycles, it will not be possible to switch the compressor on again until the DTC memory has been erased.

1. Various versions of Coolant Fan Control (FC) Module -J293-, used in conjunction with high pressure sensor -G65- may be installed. At the time of publishing however, All TT equipped with -J293-/-G65- have version where coolant fan(s) -V7- speed 1 is always switched on automatically whenever the A/C clutch -N25- is energized (regardless of refrigerant system pressure).

Output Diagnostic Test Mode (DTM) (function 03)

Note. Installation locations of actuated components. Refer to A/C system control and regulation components in engine compartment and rear body and A/C system control and regulation components in passenger compartment . The Output Diagnostic Test Mode (DTM) can be performed more than once if necessary. Malfunctions in final control elements checked during the output DTM are stored as DTCs in DTC memory. Checking the Idle Air Control (IAC) regulation function. Refer to Idle Air Control (IAC) regulation, initiating Output Diagnostic Test Mode (DTM) . During output DTM, the vehicle must not be moved and the engine speed must be lower than 3000 RPM. During output DTM, the air conditioning control functions are switched off and all segments of the A/C Control Head -E87- displays are activated.

Initiating output DTM

1. Start engine.
2. Press AUTO button to switch compressor on.
3. Open instrument panel vents.
4. Set air distribution to instrument panel vents.

1. Connect VAG 1551 Scan Tool (ST). Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08 and advance program until "Select function XX" appears on display. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
3. Switch printer on by pressing PRINT button (indicator lamp in button comes on).
4. Check DTC memory. Refer to «Diagnostic Trouble Code (DTC) Memory, checking (function 02)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__diagnostic-trouble-code-dtc-memory-checking) .

Indicated on display

1. Press buttons -0- and -3- to select "Output Diagnostic Test Mode" function 03.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

Note. The --> button is used to advance through the program sequence. Output diagnostic test mode can be stopped by pressing the -C- button. When output diagnostic test mode has been completed, check DTC memory. Refer to Diagnostic Trouble Code (DTC) Memory, checking (function 02) . If, at the beginning of output diagnostic test mode the message "Function is unknown or cannot be carried out at the moment" appears on the display (e.g. if the engine is not running), press the --> button and select function 03 (output diagnostic test mode) again. (The control element "A/C clutch-N25" will no longer be activated during this test.) If the message "Function is unknown or cannot be carried out at the moment" appears on the display. Refer to Read Measuring Value Block (function 08) (display group 001).

Indicated on display

If this readout is displayed, the output DTM is ended.

1. Press --> button.

Idle Air Control (IAC) regulation, initiating Output Diagnostic Test Mode (DTM)

1. Switch ignition off.
2. Remove Engine Control Module (ECM) and connect adapter cable of VAG 1598/22 test box to ECM connector. Do not connect ECM to test box.

Refer to

1. «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-amu) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU
2. «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-atc) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): ATC
3. «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276272-S12227258552008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AWP
4. «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276273-S13756956692008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): BEA

Note. Terminal assignments of harness connectors to ECM

Refer to

1. «24 MULTIPORT FUEL INJECTION (MFI)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-amu) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU
2. «24 MULTIPORT FUEL INJECTION (MFI)»(/audi/tt/8n-1998-2003/remont/fuel-system/#18l-4-cyl-5v-turbo-fuel-injection-ignition-engine-codes-atc) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): ATC
3. «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276272-S33271097972008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AWP
4. «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276273-S13509179772008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): BEA

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

1. Switch ignition on.
2. Switch rear window heater off.
3. Connect VAG 1551 Scan Tool (ST). Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
4. Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08 and advance program until "Select function XX" appears on display. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .

1. Switch printer on by pressing PRINT button (indicator lamp in the button comes on).

Indicated on display

1. Press buttons -0- and -3- to select "Output Diagnostic Test Mode" function 03.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

1. Press --> button.
2. Once again press buttons -0- and -3-.

Indicated on display

1. Press -Q- button to confirm input.

Note. If the function "Output Diagnostic Test Mode" is once again entered, the A/C clutch -N25- is no longer actuated. Refer to Read Measuring Value Block (function 08) (Display Group 001).

1. To test idling speed regulation function, connect VAG 1527 voltage tester (or equivalent LED type voltage tester) between Ground (GND) and appropriate input (for ECM) on test box.

Basic Setting (function 04)

1. Connect VAG 1551 Scan Tool (ST). Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08 and advance program until "Select function XX" appears on display. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
3. Switch printer on by pressing PRINT button (indicator lamp in button lights up).
4. Check DTC memory. Refer to ( «Diagnostic Trouble Code (DTC) Memory, checking (function 02)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__diagnostic-trouble-code-dtc-memory-checking) ) and repair any malfunctions that may be indicated.

1. Erase DTC memory. Refer to «Diagnostic Trouble Code (DTC) Memory, erasing and End Output (functions 05 and 06)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__diagnostic-trouble-code-dtc-memory-erasing) .
2. Check coding. Refer to ( «Control Module, coding (function 07)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__control-module-coding-function-07) ) and correct if necessary.

Indicated on display

1. Press buttons -0- and -4- to select "Basic Setting" function 04.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

1. Press buttons -0-, -0- and -1- to input display group number 1 (001).

1. Press -Q- button to confirm input.

Note. The following positioning motors are now activated one after the other and their end positions are stored in the A/C Control Head -E87- (using the resistance values of the potentiometers installed in the positioning motors)

1. Temperature regulator flap motor -V68
2. Central air flap motor -V70
3. Footwell/defroster flap motor -V85
4. Air flow flap motor -V71

Indicated on display

Note. The movement of the positioning motors can be followed on the display (by a change in the feedback value).

Indicated on display

When "0" appears on the display, basic setting has ended.

1. Press --> button.

Indicated on display

1. Press buttons -0- and -2- to select "Check DTC Memory" function 02.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display (the number of stored DTCs or "No DTC recognized" is displayed.

1. Press --> button.

Stored DTCs are displayed and printed one after the other.

When the last DTC has been displayed and printed out, the malfunction must be repaired using the DTC table. Refer to Diagnostic Trouble Code (DTC) table .

1. Press --> button.

Indicated on display

Diagnostic Trouble Code (DTC) Memory, erasing and End Output (functions 05 and 06)

Requirement

1. DTC memory checked

Erase DTC Memory (function 05)

1. Press --> button.

Indicated on display

1. Press buttons -0- and -5- to select "Erase DTC Memory" function 05.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

1. Press --> button.

Indicated on display

Note. If the text shown opposite appears on the display, the test procedure has not been performed correctly. Follow the test procedure exactly

1. Check DTC memory.
2. Repair any malfunctions and check DTC again.
3. Erase DTC Memory.

1. If for example, the ignition was switched off between checking and erasing DTC memory is not erased (check DTC memory once again).

End Output (function 06)

Note. DTC memory has been checked and erased, basic setting has been performed, and the coding has been checked.

Indicated on display

1. Press buttons -0- and -6- to select "End Output" function 06.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

1. Switch ignition off and disconnect Data Link Connector (DLC).

Control Module, coding (function 07)

Coding A/C Control Head -E87

Note. The basic setting must be performed after each coding operation. Refer to Basic Setting (function 04) . If the display of a newly installed A/C Control Head -E87- flashes (for approx. 2 minutes) after the ignition has been switched on, code the A/C Control Head -E87- and perform basic setting.

1. Connect VAG 1551 Scan Tool (ST). Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08 and advance program until "Select function XX" appears on display. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
3. Switch printer on by pressing PRINT button (indicator lamp in button comes on).

Indicated on display

1. Press buttons -0- and -7- to select "Code Control Module" function 07.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

Note. The --> button is used to advance through the program sequence.

1. Code A/C Control Head -E87- according to vehicle type, engine and export version. Refer to «Coding»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

1. Press -Q- button to confirm input.

After a short delay, the control module identification (version), coding and dealership number (where the control module was coded) are displayed ("Klimavollautomat" = fully automatic air conditioner).

1. Perform basic setting. Refer to «Basic Setting (function 04)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__basic-setting-function-04) .

Note. Any invalid codes entered in the A/C Control Head -E87- are ignored and coding "00001" is stored as a default. Allocation of the A/C Control Head -E87- (dependent on vehicle equipment).

Coding

Coding example

Read Measuring Value Block (function 08)

Note. A/C control heads -E87- with part numbers without index letter have 10 measuring value blocks (display groups), each showing 4 measuring values (display fields). A/C control heads -E87- with part numbers including index letter "A", and onward have 11 measuring value blocks (display groups), each showing 4 measuring values (display fields). Regulation of the air conditioning remains functional during the On Board Diagnostic (OBD) Read Measuring Value Block" function 08 and the current measured values are displayed. Display groups 2 through 5 show the current actual or specified values and the learned values (stored during the last basic setting) for the end stops of the individual positioning motors. The positions of the positioning motors and flaps can be changed during the OBD using the control buttons on the A/C Control Head-E87-, and the current actual and specified values are displayed on the VAG 1551 Scan Tool (ST). If the printer is switched on, the current display will be printed out.

Read Measuring Value Block (function 08), initiating

1. Start engine.
2. Set A/C Control Head -E87- to AUTO mode (compressor is switched on).
3. Allow fresh-air blower to run at high speed for approx. 1 minute (to allow positioning motors to settle into their final positions).
4. Connect VAG 1551 Scan Tool (ST). Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .

1. Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08 and advance program until "Select function XX" appears on display. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .

Indicated on display

1. Press buttons -0- and -8- to select "Read Measuring Value Block" function 08.

Indicated on display

1. Press -Q- button to confirm input.

Indicated on display

1. Input display group number (overview. Refer to «Overview of display group numbers which can be selected»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__overview-of-display-group-numbers-which) ).
2. Press -Q- button to confirm input.

Indicated on display

To select another display group

1. Press -C- button.

Indicated on display

1. Input display group number.

Note. Pressing the -3- button advances the program to the next display group. Pressing the -1- button moves the program back by one display group.

If all the display fields show the specified values

1. Press --> button.

Indicated on display

Overview of display group numbers which can be selected

1) Only vehicles with immobilizer in conjunction with A/C Control Head -E87- with part number suffix "A" and onwards.

Display group 001 - Compressor cut-off conditions, voltage for A/C clutch and at terminal 15

Note. If compressor cut-off condition 1, 8, 11 or 12 exists, the A/C clutch -N25- cannot be actuated during the output diagnostic test mode. Refer to Output Diagnostic Test Mode (DTM) (function 03) . If compressor cut-off condition 5 appears together with another compressor cut-off condition, disregard cut-off condition 5. If several compressor cut-off conditions exist simultaneously (display field 1), the display will either show them all alternately or it will show only the cut-off condition which is assigned the highest priority by the A/C Control Head -E87-. If the A/C pressure switch -F129- is open, compressor cut-off condition 1 (excess pressure) will appear initially and the compressor is switched off. If -F129- remains open for more than 30 seconds, the system will switch to compressor cut-off condition 3 (low pressure, refrigerant circuit empty). As a running change in production, pressure switch -F129 is replaced by high pressure sensor -G65-. High pressure sensor -G65- transmits a square wave signal at a rate which varies according to the refrigerant system pressure. Refer to . Coolant Fan Control (FC) Module -J293 reacts to the pulse rate of the signal from high pressure sensor -G65 as follows: 1) It informs the A/C Control Head -E87- that the pressure in the refrigerant system is OK and that A/C clutch -N25- can be switched on (compressor is switched on via -J293-. 2) If the refrigerant system pressure rises, the control unit switches the radiator fan to speed 2.

Display group 002 - Temperature regulator flap motor -V68

Display group 003 - Central air flap motor -V70

Display group 004 - Footwell/defroster flap motor -V85

Display group 005 - Air flow flap motor -V71

Display group 006 - Calculated ambient temperature for outside air temperature display -G106-, measured values from fresh air intake duct temperature sensor -G89- and outside air temperature sensor -G17- and sunlight photo sensor -G107

Display group 007 - Sender for outlet temperature, floor outlet -G192-, instrument panel interior temperature sensor -G56-, calculated coolant temperature

Display group 008 - Voltage at fresh air blower -V2- and voltage at terminals 58d/s

Display group 009 - Engine speed (RPM), vehicle speed, auxiliary heater and key allocation

Display group 010, display fields 1 - 3 - Excessive coolant temperature signal, A/C compressor cut-in/out, A/C pressure switches -F129-/-G65, signal from convertible top control module -J256

Display group 010, display field 4 - Signal from convertible top control module -J256

Note on display field 1

Checking coolant temperature and instrument cluster. Refer to 90 INSTRUMENTS .

Notes on display field 2

1. When A/C clutch -N25- is switched on the output is closed (voltage greater than 5 V).
2. If the voltage falls below 5 V while the A/C clutch is switched on (engine control module switches input to Ground), the A/C Control Head -E87- will switch A/C clutch -N25- off. Refer to «Display group 001 - Compressor cut-off conditions, voltage for A/C clutch and at terminal 15»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__display-group-001-compressor-cut-off) , display group 001, display field 1 and appropriate wiring diagram. Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

Notes on display field 3

1. The function of radiator fan control unit -J293 and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129 or high pressure sensor -G65-.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

1. When A/C pressure switch -F129- is open (high/low pressure switch between terminals 1 and 2) the compressor is switched off. Refer to «Display group 001 - Compressor cut-off conditions, voltage for A/C clutch and at terminal 15»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__display-group-001-compressor-cut-off) display group 001, display field 1.
2. If the refrigerant system pressure is less than 1.4 bar or greater than 31 bar, the Coolant Fan Control (FC) Module -J293- (on vehicles with high pressure sensor -G65-) will not send any voltage signal to -E87 and A/C clutch -N25- will be disengaged.

Notes on display zone 4

1. On Audi TT Coup, display should always read "0".
2. On Audi TT Roadster, convertible top control module -J256- sends a ground signal to -E87- (display reads "1") when the convertible top is open. If a hardtop is fitted, -J256- does not send a ground signal to -E87- (display reads "0").

Refer to 01 ON BOARD DIAGNOSTIC (OBD)

1. When the convertible top is opened on Audi TT Roadsters, A/C regulation is altered. Instead of using the measured value from instrument panel interior temperature sensor -G56-, the system assumes pre-programmed outlet temperature values based on the current outside temperature. -E87- receives this information via terminal 5 in connector C from convertible top control module -J256-.

Display group 011 (last four compressor cut-off conditions recognized)

Notes

1. Display group "011" is only available on -E87- with part number suffix "A." and onwards.
2. Only compressor cut-out conditions valid for more than 20 seconds are stored.

A/C Control Head -E87-, electrical testing

Note. The VAG 1598 test box and adapters must never be connected to the A/C Control Head -E87- while performing an on board diagnostic program with VAG 1551/1552 Scan Tool (ST).

Special tools, testers and auxiliary items

Scheme 2

1. VAG 1598 test box with VAG 1598/11 and VAG 1598/12 adapter cables
2. Multimeter (Fluke 83 or equivalent)
3. VW 1594 connector test kit
4. VAG 1527B voltage tester (or equivalent diode type tester)

1. Temperature sensor with suitable tester

Test conditions

1. All fuses OK according to wiring diagram

Connecting VAG 1598 test box to connector for A/C Control Head -E87- using VAG 1598 adapters 11 and 12

1. Switch ignition off.
2. Remove A/C Control Head -E87-. Refer to «A/C Control Head -E87-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-control-head-e87-removing-and) .

1. Connect adapter leads VAG 1598/11 and 12 to connectors on vehicle wiring harness.

Note. Do not connect A/C Control Head -E87-. To carry out the measurement, connect the VAG 1598 test box to the relevant adapter lead. The socket assignment on VAG 1598/12 adapter corresponds exactly to the terminal assignment on the A/C Control Head -E87-. The socket assignment on VAG 1598 adapter does not correspond to the terminal assignment on the A/C Control Head -E87-. Refer to Socket assignment for VAG 1598 test box with adapter lead VAG 1598/11 .

Socket assignment for VAG 1598 test box with adapter lead VAG 1598/11

Note. The terminal assignment for connectors A and B on the VAG 1598/11 adapter does not match the socket assignment on the test box. The terminal assignment for connector C on the VAG 1598/11 adapter corresponds exactly to the socket assignment on the test box. The terminal assignment for connector D on the VAG 1598/12 adapter corresponds exactly to the socket assignment on the test box. Because the connectors for the A/C Control Head -E87- are distributed over two adapter leads (VAG 1598/11 and VAG 1598/12) there is no Ground (GND) connection for testing purposes when only adapter lead VAG 1598/11 is connected. Therefore, for various steps of the electrical test it is necessary to use a suitable Ground (GND) point on the body of the car, or to use a second VAG 1598 test box. With the VAG 1598/12 adapters the Ground (GND) connection is through terminal 15.)

A/C Control Head -E87-, electrical test summary

Test step 1 - Voltage supply, Ground (GND) connection, illumination for A/C Control Head -E87-, signal for "ignition off" period

Note. If necessary, the Ground (GND) connection in test step 1.2 can be made via connector D, terminal 15.

Test step 1 continued

Test step 1 continued

Test step 1 continued

Test step 2 - Temperature sensors/sensors (-G17-, G98-, G192-)

Resistance values (dependent on ambient temperature) for temperature sensors in k ohms

Test step 3 - Fresh air blower -V2- with control module -J126

Test step 3 continued

Test step 4 - A/C flap position sensors (in flap motors) (-V68-/-G92-, -V70-/G112-, -V71-/-G113-, -V85-/-G114-)

Test step 4 continued

Note. The resistance of the potentiometers in the positioning motors can only be measured at the motors themselves (they are connected in parallel) (specification: 3.6 k ohms to 5.7 k ohms , between terminals 1 and 3). The resistance of the potentiometers in the flap motors (between terminals 1 and 2 and between terminals 3 and 2) depends on the position of the motor, and must always be measured with the motor installed. The maximum specified value will not be obtained in test steps 4.1 and 4.2. To obtain the maximum specified value, all the connectors on the other flap motors would have to be disconnected; (motors are connected in parallel). If the A/C Control Head -E87- detects the malfunction "Potentiometer short circuit to Ground" or "Open/short circuit to B+," test all the potentiometers (one in each of the 5 positioning motors) and the wiring. If the readout for DTC memory shows that more than one of the positioning motors is malfunctioning but no DTCs are identified in test step 4, test for short circuits in the wiring to and between the individual positioning motors (e.g. between -V70- and -V71-).

Test step 4 continued

Test step 5 - A/C pressure switch -F129-, signal from Coolant Fan Control (FC) Module -J293-, output for "A/C compressor cut-in/out", signal indicating "excessive coolant temperature"

Test step 5 continued

Test step 5 continued

Test step 5 continued

Test step 5 continued

Test step 5 continued

Test step 5 continued

Test step 6 - Activation of coolant fan(s) -V7-, activation of A/C clutch -N25

Note. On vehicles equipped with A/C pressure switch -F129-, coolant fan(s) -V7- are switched on whenever A/C clutch -N25- is activated. Various versions of Coolant Fan Control (FC) Module -J293-, used in conjunction with high pressure sensor -G65- may be installed. At the time of publishing however, All TT equipped with -J293-/-G65- have version where coolant fan(s) -V7- speed 1 is always switched on automatically whenever the A/C clutch -N25- is energized (regardless of refrigerant system pressure).

Test step 6 continued

Coolant Fan Control (FC) Module -J293-, electrical testing

Special tools, testers and auxiliary items

1. Multimeter (Fluke 83 or equivalent)
2. VW 1594 connector test kit
3. VAG 1527B voltage tester (or equivalent diode type tester)
4. VAS 5051 Vehicle Diagnostic Testing and Information System for testing square wave (pressure) signal on vehicles with high pressure sensor -G65-.

Test conditions

1. All fuses OK according to wiring diagram
2. DTC memory of A/C Control Head -E87- checked - no DTCs stored.
3. No compressor shut-off conditions displayed in read measuring value block (Display Group 01, display field 1) for A/C Control Head -E87- while engine is running.
4. A/C Control Head -E87- installed.

1. Connectors A and B detached from -J293-.

Coolant Fan Control (FC) Module -J293- (vehicles with A/C pressure switch -F129-), electrical testing

Scheme 3

Terminal assignments at -J293- (vehicles with -F129-)

Location: In engine compartment on left long member.

Function

1. Activates coolant fan(s) -V7- (speeds 1 and 2)
2. Activates A/C clutch -N25-.

Note. The function of -J293 and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129 or high pressure sensor -G65-.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

Scheme 4

Terminal assignments and switching conditions (A/C pressure switch -F129-)

1. Switch between terminals -1- and -2- opens if there is excess pressure or insufficient refrigerant system pressure (A/C clutch -N25- is disengaged).
2. Switch between terminals -3- and -4- closes when refrigerant system pressure rises (coolant fan(s) -V7- switched to speed 2).

Switching conditions - Coolant Fan Control (FC) Thermoswitch -F18/-F54

1. F54 between terminals 1 and 2: Closes at approx. 95 °C (-V7- switched to speed 1).
2. F18 between terminals 3 and 2: Closes at approx. 102 °C (-V7- switched to speed 2).

Switching conditions - Engine Coolant Temperature (ECT) Waring Switch -F14

1. Switch opens at approx. 118 °C - compressor is switched off.

Note. F14- is only installed on vehicles with A/C pressure switch -F129-.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

Test step 1 - Voltage supply, Ground (GND) supply

Test step 2 - Activation of coolant fan(s) -V7

Test step 2 continued

Test step 2 continued

Test step 3 - Activation of A/C clutch -N25

Test step 3 continued

Coolant Fan Control (FC) Module -J293- (vehicles with high pressure sensor -G65-), electrical testing

Scheme 5

Terminal assignments at -J293- (vehicles with -G65-)

Location: In engine compartment on left long member

Function

1. Activates coolant fan (s) -V7 (speeds 1 and 2)
2. Activates A/C clutch -N25
3. Processes the square-wave signal from high pressure sensor -G65- and sends a positive signal to -E87- to indicate the refrigerant system pressure is OK.
4. Switches on after-run coolant pump -V51 (if equipped) for continued coolant circulation when the ignition is switched on. The pump continues to operate for a short time after the ignition has been switched off.

Note. The following -J293- connector A terminals are vacant

Terminal 1 (on vehicles without after-run coolant pump -V51-)

Terminals 3, 5, 11 and 14

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

1. J293- connector A,, terminal 13 is intended for disengaging -A/C clutch -N25- when the instrument cluster sends "excessive coolant temperature" signal. As disengagement of -N25- also takes place via the A/C Control Head -E87-, -J293- terminal 13 may be vacant on some vehicles, dependant of vehicle wiring configuration.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

1. The function of Coolant Fan Control (FC) Module -J293 and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129 or high pressure sensor -G65-.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

1. Various versions of Coolant Fan Control (FC) Module -J293-, used in conjunction with high pressure sensor -G65- may be installed. At the time of publishing however, All TT equipped with -J293-/-G65- have version where coolant fan(s) -V7- speed 1 is always switched on automatically whenever the A/C clutch -N25- is energized (regardless of refrigerant system pressure).

Scheme 6

Terminal assignments and switching conditions (high pressure sensor -G65-)

Terminal -1- Ground (GND)

Terminal -2- Signal output (square-wave signal to -J293- and ECM)

Terminal -3- Positive (terminal 15)

Note. When electrical connector at -B- is disconnected, the A/C clutch -N25- cannot be activated. High pressure sensor -A- transmits a square-wave signal at a pulse rate that varies according to the refrigerant system pressure. Checking. Refer to High pressure sensor -G65- signal, checking .

Switching conditions - Coolant Fan Control (FC) Thermoswitch -F18/-F54

1. F54- between terminals 1 and 2: Closes at approx. 95 °C (-V7- switched to speed 1).
2. F18- between terminals 3 and 2: Closes at approx. 102 °C (-V7- switched to speed 2).

Test step 1 - Voltage supply, Ground (GND) supply

Test step 2 - Activation of coolant fan(s) -V7

Test step 2 continued

Test step 3 - Activation of A/C clutch -N25

Test step 3 continued

Note. J293- connector A, terminal 13 is intended for disengaging -A/C clutch -N25- when the instrument cluster sends "excessive coolant temperature" signal. As disengagement of -N25- also takes place via the A/C Control Head -E87-, -J293- terminal 13 may be vacant on some vehicles, dependant of vehicle wiring configuration. Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations If connector A terminal 13 is grounded, coolant fan(s) -V7- are activated and -N25- will not be activated.

Test step 3 continued

Test step 4 - Signal from high pressure sensor -G65

Note. Signal generated by -G65- is refrigerant system pressure-dependent. Checking -G65- signal. Refer to High pressure sensor -G65- signal, checking . If no electrical malfunctions can be determined, check refrigerant system pressures. Refer to A/C refrigerant system pressures, checking . The refrigerant pressure signal from -G65- is also input to the Motronic Engine Control Module (ECM) -J220-. This input is needed in order to react to variable A/C compressor loads dependant of refrigerant system pressure. This signal may or may not appear as a duty cycle on the read measuring value block display. Refer to 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): ATC 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AWP 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): BEA .

Scheme 7

A- Refrigerant system pressure, "high pressure side" (in bar)

B- Signal ratio of square-wave signal

C- Characteristic curve

Note. Coolant Fan Control (FC) module -J293- sends a positive signal to A/C Control Head -E87- whenever the signal ratio is between 13% (equivalent to approx. 1.2 bar) and 78% (equivalent to approx. 32 bar). If the signal ratio is lower than 13% or higher than 78%, no positive signal is sent to -E87-. Therefore -E87- does not send a signal to -J293 instructing it to energize A/C clutch -N25. If the refrigerant system pressure rises above 32 bar (signal ratio higher than 78%), control unit -J293 will wait until the pressure has fallen below 24 bar (signal ratio lower than 65%) before starting to send a positive signal again.

Note. Coolant Fan Control (FC) Module -J293- switches coolant fan(s) -V7- to speed 2 whenever the refrigerant system pressure rises above 16 bar (signal ratio higher than 45%) and when Coolant Fan Control (FC) Thermoswitch -F18- is closed. If pressure falls below 12.5 bar (signal ratio lower than 37%) the control unit switches the fans back to speed 1. Various versions of Coolant Fan Control (FC) Module -J293-, used in conjunction with high pressure sensor -G65- may be installed. At the time of publishing however, All TT equipped with -J293-/-G65- have version where coolant fan(s) -V7- speed 1 is always switched on automatically whenever the A/C clutch -N25- is energized (regardless of refrigerant system pressure). Check refrigerant system pressures. Refer to A/C refrigerant system pressures, checking . The refrigerant pressure signal from -G65- is also input to the Motronic Engine Control Module (ECM) -J220-. This input is needed in order to react to variable A/C compressor loads dependant of refrigerant system pressure. This signal may or may not appear as a duty cycle on the read measuring value block display. Refer to 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): ATC 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AWP 01 ON BOARD DIAGNOSTIC (OBD) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): BEA .

High pressure sensor -G65-, checking signal

1. Connect oscilloscope test leads to -G65- signal wire. Refer to «Test step 4 - Signal from high pressure sensor -G65»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__test-step-4-signal-from) electrical testing, step 4.

Scheme 8

The oscilloscope shows this signal pattern under the following conditions

1. Ignition switched on (-G65- connected to positive and GND).
2. Oscilloscope settings: 2 V/Div. = (2 volts per grid division, direct current) 5 ms/Div. (5 milliseconds per grid division).
3. Oscilloscope test lead (signal wire) connected to terminal 2 on -G65-.
4. Oscilloscope test lead (shielding) connected to GND.

Note. Signal pattern illustrated corresponds to a refrigerant system pressure of approx. 5 bar (equivalent to a signal ratio of approx. 20%). This is the pattern that occurs at an ambient temperature of 20 °C (68 °F) when the compressor is not running and the refrigerant circuit is full. Pulse width -A- varies according to refrigerant system pressure. When the pressure rises, the pulse width increases. Interval -B- between signals is always 20 milliseconds. The signal ratio is the ratio between pulse width -A- and signal interval -B-.

Scheme 9

1. Hose clamps 3094

Used for removing the complete heating and A/C unit (with heater core and evaporator).

Scheme 10

1. Body saw VAG 1523A (or equivalent)

Used for removing the complete heating and A/C unit (with heater core and evaporator).

A/C refrigerant system, safety measures

1. The subassemblies and lines of the air conditioner are filled with tetrafluoroethane, also known as refrigerant R-134a.

1. Refrigerant R-134a replaces the refrigerant R-12 which is reported to have harmful effects on the earth's ozone layer.
2. R-134a and R-12 systems are similar in design but there are very important differences in the refrigerants, lubricating oils, service equipment and A/C system components.

A/C refrigerant system, general repair guidelines

The refrigerant circuit of the air conditioning system must not be drained and opened unless this is necessary because of safety precautions, or unless components of the refrigerant circuit of the air conditioning system have to be replaced. Refer to A/C refrigerant system, safety measures .

When performing all other usual vehicle repair work, the refrigerant circuit of the air conditioning system should remain closed.

Servicing operations which can be performed on the heating and air conditioning system without opening the A/C system are described in this article from A/C refrigerant system, servicing .

For servicing operations to A/C system that require discharging the A/C system. Refer to Refrigerant R134a - Servicing

Note. The connections for pressure switches and sensors mentioned in this Repair article are provided with a valve which closes automatically when the switches are unscrewed. These switches can be replaced even though the A/C system is fully charged.

Scheme 11

O-rings seal the connections between components of the A/C system.

Use only O-rings which are compatible with R-134a refrigerant and refrigerant (PAG) oil. Refer to the most recent parts information when obtaining new O-rings.

O-rings are recognized by colors (currently red, green or violet). Under certain conditions, black O rings may also be installed in production.

Note. Use O-rings only once and always replace. Handle the O-rings only in a clean working environment. Always use correct size O-rings (dimensions -a- and -b-). Lubricate the O-rings with refrigerant (PAG) oil before installing. Always make sure to properly install the O-rings on line/component mounting flanges/grooves. O-ring and torque specifications also apply to the threaded connections in the A/C lines.

Commercial designation

Obtain R-134a refrigerant (tetrafluoroethane) from a local A/C supplier under one of the following names

1. H-FKW 134a
2. SUVA ® 134a
3. KLEA 134a

Note. R-134a refrigerant is packaged in different containers. Use only R-134a that comes in containers having correct types of service fittings.

Color

Refrigerant R-134a is colorless and is invisible as a gas. Only the layer between the gas and the fluid is visible (fluid level in the tube of the cylinder or bubbles in the sight glass in the fluid reservoir). R-134a when viewed through a sight glass (if installed) may appear milky due to the mixing of refrigerant and lubricating oil (PAG oil).

Airborne properties

Escaped refrigerant gases are heavier than air and will gather first in low places, like under the car.

Solubility of refrigerant oil

A required special refrigerant oil Polyalkylene Glycol (PAG) synthetic oil is used to lubricate cylinder walls and bearings and enters the A/C system to some degree. This oil is NOT compatible with mineral based oils used in R-12 systems.

Note. R12 refrigerant systems use mineral oils which are not dissolved by R-134a refrigerant and are unusable.

Effects on the environment

Because R-134a does not contain chlorine atoms, the major catalyst in ozone depletion, R-134a has no ozone depletion potential.

R-134a does not cause smog and has a considerably lower global warming potential (greenhouse effect) than R-12 refrigerant. Nonetheless, do not release R-134a into the environment and always recover/recycle using approved service equipment.

Toxicity

Refrigerant R-134a is non-toxic up to a temperature of 101 °C (214 °F) and is safe when handled and used properly.

Above 101 °C (214 °F), gas pressure is above 39.5 bar (573 psi) and R-134a begins to decompose into poisonous gases (hydrogen fluoride, carbonyl fluoride and fluorine). These gases give adequate warning of their presence since they cause irritation of the mucous membrane (throat).

Refrigerant R-134a gas has no effect on foodstuffs; it does not poison food or make it inedible.

Temperature/pressure relationship

In a partially charged refrigerant container, refrigerant gas comes to the surface, which under particle formation becomes fluid. This occurs under pressure and is know as gas pressure. Similar to R-12 refrigerant, the gas pressure of R-134a is temperature dependent.

Effects on plastics

Refrigerant R-134a will deteriorate some plastics. When system temperature drops, these plastics can be deposited at the expansion valve or restrictor causing blockage. Therefore, when making system repairs, use only genuine Audi replacement parts which are specified for use with R-134a refrigerant.

Effects on metal

In its pure state, refrigerant R-134a is chemically stable and will not attack iron or aluminum. However, the mixture of R-134a and PAG oil may deteriorate certain metals (copper) which could lead to blockage, leaks or deposits on the compressor piston. Therefore, when making system repairs, use only genuine Audi replacement parts which are specified for use with R-134a refrigerant.

Critical temperature/critical pressure

R-134a refrigerant will remain chemically stable up to a pressure of 39.5 bar (573 psi). This corresponds to a temperature of 110 °C (230 °F). Above this temperature the refrigerant deteriorates. Refer to Flammability Flammability.

Water solubility

Liquid R-134a refrigerant will absorb only very minute quantities of moisture. However, R-134a vapor can absorb large amounts of moisture.

Water in the system forms ice in the expansion valve or restrictor causing the system to stop cooling. In addition, moisture combines with the refrigerant to form acids which will damage the system.

Flammability

R-134a refrigerant is not flammable. In fact, it tends to inhibit combustion and has a fire extinguishing effect. However, a flame or glowing hot surface, as well as ultraviolet light (from electric welding), will decompose the refrigerant into poisonous gases (hydrogen fluoride, carbonyl fluoride and fluorine). These gases give adequate warning of their presence since they cause irritation of the mucous membrane (throat).

R-134a can become flammable at pressures above ambient pressure in conjunction with air concentrations greater than 60% by volume.

Refrigerant containers

There must be pressure space available in the fluid area of the container. At increasing temperatures the fluid expands, the space filled with vapor becoming smaller. At a specific point there will only be fluid in the container. Beyond this point, only a slight increase in temperature will result in a very high pressure in the container.

Leak detection

Use halogen leak detector Hitec HI400A-TEL, or equivalent, to check for R-134a system leaks. This tool can also be used to detect leaks in R-12 systems. Many currently available R-12 leak detectors cannot detect R-134a refrigerant leaks.

A/C refrigerant oil (PAG), properties

A special Polyalkylene Glycol (PAG) synthetic oil is used in R-134a systems. This oil is NOT compatible with mineral based oils used in R-12 systems. See safety measures starting on A/C refrigerant system, safety measures , for Warnings and Cautions regarding proper oil usage.

A/C refrigerant system, servicing

Note. Always observe safety measures. Refer to A/C refrigerant system, safety measures . Checking A/C cooling performance. Refer to A/C cooling performance, testing . Checking refrigerant system pressures. Refer to A/C refrigerant system pressures, checking Discharging refrigerant system. Refer to Refrigerant R134a - Servicing Evacuating and recharging refrigerant system. Refer to Refrigerant R134a - Servicing Leak testing. Refer to Refrigerant R134a - Servicing Symptom based troubleshooting. Refer to Refrigerant R134a - Servicing A/C system components identified with an asterisk (*) may only be serviced or replaced after properly discharging refrigerant system. A/C system components not identified with an asterisk (*) can be serviced or replaced without discharging refrigerant system.

Scheme 12

1. Compressors supplied as replacement parts already contain the full quantity of refrigerant oil required for the A/C system. Refer to . Refer to Refrigerant R134a - Servicing
2. Do not add refrigerant to the A/C system. Always discharge, evacuate and recharge system.
3. The tightening torques and O-ring diameters given also apply to the threaded connections for the refrigerant lines between components.
4. Install only O-rings that are approved for use with refrigerant R134a (currently color-coded red, light purple and dark purple).

1 - Oil drain plug *

2 - A/C clutch -N25

1. Servicing. Refer to «A/C Clutch -N25-, servicing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

HD = high pressure side

ND = low pressure side

3 - A/C Compressor *

Removing and installing (refrigerant pipes remain connected)

1. 4-cylinder engine. Refer to «A/C Compressor - 4-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-compressor-4-cyl-engine-removing)
2. 6-cylinder engine. Refer to «A/C compressor - 6-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

Note. Removing and installing compressor bracket from engine. Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP . Removing and installing compressor bracket from engine. Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK .

HD = high pressure side

ND = low pressure side

4 - Pressure relief valve *

5 - Condenser *

6 - Receiver drier*

7 - Service valve *

1. High pressure side

Note. Depending on engine type, it may be necessary to remove the front suspension cross-brace in order to access service valve.

8 - Cap

1. With seal.
2. Always re-install after using connection.

9 - Connection with valve *

HD = high pressure side

ND = low pressure side

10 - A/C pressure switch -F129- or high pressure sensor -G65

1. As a running change in production, pressure switch -F129- is replaced by high pressure sensor -G65-.
2. The function of Coolant Fan Control (FC) Module -J293- and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129- or high pressure sensor -G65-.
3. F129- switch functions. Refer to «A/C pressure switch -F129-, switch functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-pressure-switch-f129-switch-functions) .
4. F129- removing and installing. Refer to «Removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

1. G65- function, checking signal. Refer to «High pressure sensor -G65- signal, checking»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. G65- removing and installing. Refer to «High pressure sensor -G65-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

11 - Expansion valve *

HD = high pressure side

ND = low pressure side

12 - Evaporator *

13 - Cap

1. With seal.
2. Always re-install after using connection.

14 - Service connection *

1. Low pressure side

15 - Damper *

HD = high pressure side

ND = low pressure side

A/C pressure switch -F129-, switch functions

The high/low pressure switch (located between terminals -1- and -2-) disengages A/C clutch -N25- (via A/C control head -E87-) when there are excessively high or low refrigerant system pressures.

Switching pressures (in bar)

Switch open (A/C clutch -N25- off)

1. Low pressure: switch opens at 1.2 bar and closes at 2.4 bar
2. High pressure: switch opens at 32 bar and closes at 24 bar

Switch closed (compressor on)

1. 1.2 (2.4) bar to 32 (24) bar

The high pressure switch (between terminals -3- and -4-) switches coolant fan(s) -V7- to speed 2.

Switching pressures (in bar)

1. Fan speed 2 on (switch closes) at 16 bar
2. Fan speed 2 off (switch opens) at 12.5 bar

Scheme 13

1. Disconnect harness connector.
2. Remove A/C pressure switch -B-.

Tightening torque: 5 Nm (44 in. lb)

1. Replace O-ring seal -A- (10.8 mm x 1.8 mm). Refer to «O-rings»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

1. To test A/C cooling efficiency with switch removed, bridge terminals -1- and -2- on connector -B-.

Note. Refrigerant system remains closed due to Schrader valve under switch in line connection.

Checking

1. Start engine.
2. Switch compressor on (select AUTO mode).

If the compressor is activated

1. Disconnect harness connector -B- from switch.
2. A/C Compressor will stop (low pressure switch open).
3. Remove switch -A- and install harness connector -B-.

A/C Compressor will not be activated (low pressure switch open).

If the compressor is not activated

1. Disconnect harness connector -B- from switch -A- and bridge terminals -1- and -2- on harness connector -B-.

The compressor will be activated.

Note. If the compressor is activated when the terminals are connected together, refrigerant system pressure is low or system is empty (check refrigerant system pressures. Refer to A/C refrigerant system pressures, checking ), or the switch is malfunctioning. If the compressor is not activated and the measuring value block display indicates A/C pressure switch -F129- as the cut-off condition, there is an open circuit in the wiring between A/C pressure switch -F129- and A/C control head -E87-. Trace and repair open circuit after performing electrical test. Refer to A/C Control Head -E87-, electrical testing .

Scheme 14

1. Disconnect electrical connection.
2. Remove high pressure sensor -B-.

Tightening torque: 5 Nm (44 in. lb)

1. Replace O-ring seal -A- (10.8 mm x 1.8 mm). Refer to «O-rings»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Note. A/C cooling efficiency cannot be checked with -G65- removed or disconnected. Coolant Fan Control (FC) Module -J293- will not energize A/C clutch -N25-. Refrigerant system remains closed due to Schrader valve under sensor in line connection. Checking signal. Refer to High pressure sensor -G65- signal, checking . Checking refrigerant system pressures. Refer to A/C refrigerant system pressures, checking

A/C refrigerant system, quick coupling service connections

Note. Use only the specified quick coupling connectors resistant to R-134a and respective refrigerant oils. Connections for the high and low pressure sides have different outside diameters. Before removing the valve or valve stems, discharge refrigerant system. Refer to A/C refrigerant system, discharging . Always reinstall sealing cap over service valve.

1. Location in A/C system. Refer to «A/C refrigerant system, servicing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Scheme 15

Quick coupling service connection, high pressure side

1 - Fitting with inside thread

2 - O ring, 10.8 mm x 1.8mm

3 - Quick coupling service connection with inside thread for sealing cap M8 x 1 and provision for O-ring

4 - O ring for sealing cap

5 - Sealing cap

Scheme 16

Quick coupling service connection, low pressure side

1 - Fitting with outside thread and provision for O ring

2 - O ring, 7.6 mm x 1.8mm

3 - Quick coupling service connection with inside thread for sealing cap M8 x 1 and provision for O-ring

4 - O ring for sealing cap

5 - Sealing cap

Scheme 17

A/C refrigerant system with expansion vale and receiver drier

Pressures and temperatures in the A/C system vary depending on engine speed (RPM), coolant fan speed, engine coolant temperature, A/C clutch engagement, outside temperature and humidity, cooling demand etc.

Pressure and temperature specifications are to be used as a reference only, and are based on the following operating conditions

1. Engine speed 1500 - 2000 RPM
2. Outside temperature of 20 °C (68 °F)

Component listing, pressure and temperature specifications. Refer to Pressure and temperature specifications .

To check system pressures, pressure testing equipment must be connected to the service valves. Checking refrigerant system pressures. Refer to A/C refrigerant system pressures, checking .

Note. Small -arrows- indicate direction of refrigerant flow. At 20 °C (68 °F) with engine not running, refrigerant system pressure equalizes to approx. 4.7 bar (68.2 psi). Refer to Temperature/pressure relationship . Refrigerant system pressures are regulated and maintained within certain tolerances by the variable displacement compressor independent of engine speed (RPM).

ND = low pressure side

HD = high pressure side

Pressure and temperature specifications

1. Refer to «A/C refrigerant system, pressures and temperatures»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) for placement of components (listed below) in refrigerant circuit.

A/C Clutch -N25-, servicing

Preparation

1. Remove compressor from bracket

1. 4-cyl. engine. Refer to «A/C Compressor - 4-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-compressor-4-cyl-engine-removing) .
2. 6-cyl. engine. Refer to «A/C compressor - 6-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

A/C Clutch, servicing

1. Sanden compressor. Refer to «Sanden compressor»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Zexel compressor. Refer to «Zexel compressor»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Scheme 18

Note. A/C clutch versions may differ slightly from illustration. Servicing procedures remain the same.

1 - Clutch plate self-locking nut

1. Always replace
2. 15 Nm (11 ft lb)
3. Removing and installing. See «Clutch plate self-locking nut, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

2 - Clutch plate

1. Removing. See «Clutch plate, removing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

3 - Shims

1. For adjusting gap between clutch plate and belt pulley
2. Gap: 0.4 - 0.8 mm
3. Checking/adjusting gap. See «Checking and adjusting gap»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

4 - Circlip

1. Always replace
2. Must be installed correctly (flat side toward compressor)
3. Must be properly seated in groove

5 - Ribbed belt pulley

1. Removing. See «Ribbed belt pulley, removing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Clean contact surfaces before installing

6 - Circlip

1. Always replace
2. Must be installed correctly (flat side toward compressor)
3. Must be properly seated in groove

7 - Magnetic coil

1. Installing. See «Magnetic coil, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)
2. Installed with a fuse which interrupts the operation of the coil if it becomes too hot (e.g. if the compressor is not moving freely).
3. Contains protection diode -J201- for suppressing voltage peaks which may occur when the A/C clutch -N25- is disengaged.

8 - Retaining clip with bolt

9 - Retaining clip

10 - Retaining clip

11 - Screw

12 - A/C Compressor

1. Sanden SD7 - V16

13 - Threaded bushing

Scheme 19

Tightening torque: 15 Nm (11 ft lb)

Note. Use commercially available two-pin wrench (illustrated) to counter-hold clutch plate. Always replace lock nut.

Scheme 20

1. Pry off carefully using two screwdrivers -A-.

Note. If the clutch plate is installed too tightly, use a commercially available two-arm or three-arm puller to remove the clutch plate.

Scheme 21

1. Attach commercially available two-arm puller -A- at shoulder -B- and remove pulley.

Note. To avoid damaging pulley when removing, make sure the puller is properly fitted to shoulder -B-. Clean contact surface before installing. If necessary, carefully tap the pulley into place using a plastic hammer and a suitable drift (applied to the bearing inner race).

Scheme 22

1. Fit lug -C- into recess on magnetic coil -A-.
2. Make sure wiring harness -B- is correctly positioned in relation to magnetic coil -A-.

Scheme 23

Gap width = difference between distance "1" and distance "2" measured as follows

1. Measure distance "1" between belt pulley and clutch plate using depth gauge -A- (at three different points).
2. Apply 12 V to magnetic coil

1. B+ terminal to single-pin connector -D
2. Ground (GND) to compressor housing

1. Measure distance "2" between belt pulley and clutch plate using depth gauge -A- (at three different points).

Gap width (distance "1" - distance "2") must be 0.4 - 0.8 mm.

Note. The gap width must be within the tolerances around the whole circumference. The gap width can also be measured without removing the compressor (compressor installed). If the gap width is outside the specified tolerance, remove the clutch plate and adjust the gap width by removing or adding shims.

Scheme 24

Note. A/C clutch versions may differ slightly from illustration. Servicing procedures remain the same.

1 - Clutch plate bolt - 15 Nm

1. Removing and installing. See «Clutch plate bolt, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

2 - Clutch plate

1. Removing. See «Clutch plate, removing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

3 - Shims

1. For adjusting gap between clutch plate and belt pulley
2. Gap: 0.4 - 0.6 mm
3. Checking/adjusting gap. See «Clutch plate gap, checking»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

4 - Circlip

1. Always replace
2. Must be installed correctly (flat side toward compressor)
3. Must be properly seated in groove

5 - Ribbed belt pulley

1. Removing. See «Ribbed belt pulley, removing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)
2. Installing. See «Ribbed belt pulley, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

6 - Circlip

1. Always replace
2. Must be installed correctly (flat side toward compressor)
3. Must be properly seated in groove

7 - Magnetic coil

1. Installing. See «Magnetic coil, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)

8 - Felt ring

1. Always replace

9 - Bolt

10 - A/C Compressor

1. Zexel

Scheme 25

1. Use commercially available two-pin wrench (illustrated -A-) to counter-hold clutch plate. (locating pins Ø 4 mm).

Tightening torque: 15 Nm (11 ft. lb.).

Scheme 26

1. Use commercially available two-pin wrench (illustrated -A-) and fixture from A/C clutch set VAG 1719 to counter-hold clutch plate

Scheme 27

1. Remove felt ring.
2. Insert fixture VAG 1719/1 as illustrated.
3. Attach commercially available two-arm puller -B- at shoulder -A- and remove pulley.

Note. To avoid damaging pulley when removing, make sure the puller is properly fitted to shoulder -A-.

Scheme 28

1. Clean contact surface before installing.
2. Insert fixture VAG 1719/2.
3. Carefully tap pulley into place using plastic hammer.

Scheme 29

1. Fit lug into recess on magnetic coil -A-.

Scheme 30

1. Check gap between ribbed belt pulley and clutch plate

1. Gap = 0.3 - 0.6 mm

Note. The gap width must be within the tolerances around the whole circumference. The gap width can also be measured without removing the compressor (compressor installed). If the gap width is outside the specified tolerance, remove the clutch plate and adjust the gap width by removing or adding shims.

A/C system control and regulation components in engine compartment and rear body

Note. Upon completion of any A/C system repairs, always check and erase the Diagnostic Trouble Code (DTC) memory (scan tool function 02), perform basic setting (function 04) and code the A/C control head -E87- (function 07). Checking A/C cooling efficiency. Refer to A/C cooling performance, testing . Refrigerant circuit. Refer to A/C refrigerant system, servicing . All components marked with an asterisk (*) are activated during output Diagnostic Test Mode (DTM) (function 03). Refer to Output Diagnostic Test Mode (DTM) (function 03) . Note different coding possibilities for A/C control head -E87-. Refer to Control Module, coding (function 07) . Electrical testing can be performed on all components marked with a double asterisk (**). Refer to A/C Control Head -E87-, electrical testing .

1 - Air extraction vents

1. Sealing flaps in vent must move freely and close automatically.
2. Checking. Refer to «Air extraction vents, checking»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__air-extraction-vents-checking) .

Note. To ensure proper ventilation of the passenger compartment, the air ducts leading through the luggage compartment trim and to the two extraction vents (left and right under the bumper) must not be obstructed.

2 - Coolant Fan Control (FC) Module -J293- *

1. Also energizes A/C clutch -N25-.
2. The function of -J293 and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129 or high pressure sensor -G65-.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

1. Removing and installing. Refer to «Coolant Fan Control (FC) Module -J293-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

3 - Outside air temperature sensor -G17-**

1. Removing and installing

1. Remove bumper cover.

Refer to 63 BUMPERS .

1. Disconnect electrical connection.
2. Unclip sensor and remove.

4 - Condenser

1. Removing and installing. Refer to «Condenser, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__condenser-removing-and-installing) .

5 - A/C refrigerant system identification label

1. Indicates type of refrigerant used (R-134a) and system (filling) capacity.

Note. On some vehicles, A/C refrigerant system identification label may be located on the underside of the front hood or on the left fender well.

6 - A/C Compressor

1. 4-cylinder engine - removing and installing from bracket (refrigerant pipes remain connected). Refer to «A/C Compressor - 4-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-compressor-4-cyl-engine-removing) .
2. 6-cylinder engine - removing and installing from bracket (refrigerant pipes remain connected). Refer to «A/C compressor - 6-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Removing and installing. Refer to «A/C compressor, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-compressor-removing-and-installing) .

7 - A/C Clutch -N25- *

1. Servicing. Refer to «A/C Clutch -N25-, servicing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Note. 4-cylinder engines - removing and installing ribbed belt. Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP . 6-cylinder engines - removing and installing ribbed belt. Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK .

8 - Service connection

1. High pressure side
2. Used to discharge or charge refrigerant, as well as check refrigerant system pressures.

Note. Always replace sealing cap after using service connection. Depending on engine type, it may be necessary to remove the front suspension cross-brace in order to access service valve.

9 - A/C pressure switch -F129- or high pressure sensor -G65

1. As a running change in production, pressure switch -F129- is replaced by high pressure sensor -G65-.
2. The function of Coolant Fan Control (FC) Module -J293- and vehicle wiring layout will vary depending on whether vehicle is equipped with A/C pressure switch -F129- or high pressure sensor -G65-.
3. F129- switch functions. Refer to «A/C pressure switch -F129-, switch functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-pressure-switch-f129-switch-functions) .
4. F129- removing and installing. Refer to «Removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

1. G65- function, checking signal. Refer to «High pressure sensor -G65- signal, checking»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. G65- removing and installing. Refer to «High pressure sensor -G65-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

10 - Expansion valve

1. Removing and installing. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .
2. Removing and installing insulation. Refer to «Expansion valve insulation, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

11 - Evaporator housing drain valve

1. Checking, removing and installing. Refer to «Evaporator housing drain valve, checking, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__evaporator-housing-drain-valve-checking-removing) .

12 - Receiver drier

1. Removing and installing. Refer to «Receiver drier, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__receiver-drier-removing-and-installing) .

13 - Damper (with refrigerant line)

Note. Damper and service valve on vehicles with 6-cylinder engines are located near right strut tower, near -G65-.

14 - Service connection

1. Low pressure side
2. Used to discharge or charge refrigerant, as well as check refrigerant system pressures.

Note. Always replace sealing cap after using service connection. Damper and service valve on vehicles with 6-cylinder engines are located near right strut tower, near -G65-. Depending on engine type, it may be necessary to remove the front suspension cross-brace in order to access service valve.

15 - Air flow flap

1. Removing and installing air flow flap motor -V71-* (with motor position sensor -G113-). Refer to «Air flow flap motor -V71-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__air-flow-flap-motor-v71-removing) .

16 - Fresh air intake duct temperature sensor -G89- **

1. Removing and installing. Refer to «Fresh air intake duct temperature sensor -G89-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__fresh-air-intake-duct-temperature-sensor) .

17 - Dust and pollen filter

1. Removing and installing. Refer to «Dust and pollen filter, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__dust-and-pollen-filter-removing-and) .

Note. The dust and pollen filter element should be replaced at regular intervals. Refer to 01 MAINTENANCE .

Scheme 31

1. Disconnect electrical connections -A- and -B-.
2. Remove bolts -C-.

Note. Depending on engine and sound dampening version, improved access may be obtained by removing pipe between intercooler and/or support brace between right and left front long members.

Various A/C refrigerant pressure monitoring/control and coolant fan control versions are possible in conjunction with Coolant Fan Control (FC) Module -J293

1. Vehicles equipped with A/C pressure switch -F129-: -V7- comes on and runs at speed 1
2. Vehicles equipped with high pressure switch -G65- and Coolant Fan Control (FC) Module -J293- version "1": -V7- comes on and runs at speed 1, regardless of initial refrigerant system pressure.
3. Vehicles equipped with high pressure switch -G65- and Coolant Fan Control (FC) Module -J293- version "2": -V7- comes on and runs at speed 1 after refrigerant system pressure has reached 12 bar.

Evaporator housing drain valve, checking, removing and installing

Checking

Scheme 32

1. Ensure that flap on valve -A- is not damaged, obstructed and is able to close freely. The flap opening must face downwards.

Removing and installing

1. Fold back pre-punched flap -D- in insulation mat and remove valve.

Note. Remove valve -A- downwards from floor. When installing, make sure it is correctly positioned in bulkhead -B-. When installed, the valve must not touch flap -D- in insulation mat. The valve must not be sprayed with rustproofing wax or undercoating material. If customer complaints mention dampness in the passenger compartment, ensure duct -C- is correctly positioned in valve -A-. Two installed versions of valve are possible: version -1- through m.y. 2000 and version -2- (with two lower openings) installed as a running change from m.y. 2001.

Receiver drier, removing and installing

1. Discharge refrigerant circuit. Refer to Refrigerant R134a - Servicing

Note. Depending on engine version and sound absorbing panel, improved access may be obtained by removing support brace between left and right long-member, and/or removing connecting pipe between intercoolers.

Scheme 33

1. Remove bolt -A-, tightening torque 15 Nm (11 ft lb).
2. Detach refrigerant pipes -B-.
3. Unscrew hex nut -C-.
4. Remove bolt -D-, tightening torque 15 Nm (11 ft lb).

1. Pull receiver -G- downwards out of bracket.

Note. Replacing components. Refer to A/C refrigerant R-134a, properties Always replace both O-rings -E- and -F- (10.8 mm; 1.8 mm). Keep receiver drier sealed for as long as possible. Only remove caps immediately before installing. Receiver drier contains desiccant which quickly becomes saturated and rendered useless if the caps are left off. The removed original receiver drier contains refrigerant oil. The equivalent amount of oil must be returned to the refrigerant system in the replacement new receiver drier. It may be sufficient to adjust the quantity of refrigerant oil in the receiver drier. For example, if only slightly damaged in an accident (i.e. no refrigerant loss, no moisture or dirt in system), the A/C can be serviced by comparing the weights of the old and new receivers, then filling the new receiver drier with refrigerant oil until it weighs the same as the damaged one.

Condenser, removing and installing

1. Discharge refrigerant circuit. Refer to Refrigerant R134a - Servicing
2. Remove bumper as a complete unit.

Refer to 63 BUMPERS

Note. Depending on engine version, it may be necessary to partially loosen/move front end module forward prior to removing condenser. Where necessary, proceed as follows

Refer to 50 BODY - FRONT

1. Mark installed position of front end module at front fenders and long members with felt marker.
2. Remove front end module bolts from fenders and long members
3. Replace removed long member bolts with longer ones (approx. 100 mm) with washer.
4. Pull front end module forward as far as possible.

1. Remove receiver drier. Refer to «Receiver drier, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__receiver-drier-removing-and-installing) .

Scheme 34

1. Remove screw -A-, tightening torque 15 Nm (11 ft lb).
2. Remove refrigerant pipes -B-.
3. Remove screw -D-, tightening torque 8 Nm (71 in lb).
4. Remove radiator fans together with bracket.

Refer to

1. «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-amu-bea) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA
2. «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP

Refer to 19 ENGINE - COOLING SYSTEM for 3.2 LITER V6 4V ENGINE MECHANICAL, ENGINE CODE(S): BHE.

1. Release radiator from lock carrier and tilt backwards.

Refer to

1. «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-amu-bea) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA
2. «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP

Refer to 19 ENGINE - COOLING SYSTEM for 3.2 LITER V6 4V ENGINE MECHANICAL, ENGINE CODE(S): BHE.

Scheme 35

1. Remove condenser -a- from bottom (between lock carrier -b- and radiator -c-).

Note. Always replace O-ring -C- (10.8 mm; 1.8 mm). When installing refrigerant pipe, make sure that spring pin -E- is properly positioned. Removed condenser contains refrigerant oil that must be accounted for in refrigerant system when Condenser replacement is necessary. Refer to Refrigerant R134a - Servicing ("Replacing components").

Refrigerant pipes on expansion valve, removing and installing

1. Discharge refrigerant system. Refer to Refrigerant R134a - Servicing

Note. Depending on engine version, improved access may be obtained by removing front suspension cross brace.

1. Remove insulation -A-. Refer to «Expansion valve insulation, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Scheme 36

1. Remove screw -B-, tightening torque 8 Nm (71 in lb).
2. Remove refrigerant pipes -C- and -D-.

Note. Always replace both O-rings -E- (17.0 mm; 1.85 mm) and -F- (8.2 mm; 1.85 mm). Seal off open ends of refrigerant pipes and the connections on expansion valve. Install refrigerant pipes stress free.

Expansion valve, removing and installing

1. Discharge refrigerant circuit. Refer to Refrigerant R134a - Servicing
2. Remove refrigerant pipes from expansion valve. Refer to «Refrigerant pipes on expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__refrigerant-pipes-on-expansion-valve-removing) .

Scheme 37

1. Remove screw -A-, tightening torque 8 Nm (71 in lb).
2. Remove expansion valve -B-.
3. Remove threaded plate -E-.

Note. Always replace both O-rings -C- (14.0 mm; 1.8 mm) and -D- (10.8 mm; 1.8 mm). Seal off open connections on the evaporator. When installing expansion valve, ensure the expansion valve insulation is properly in place, and is not damaged. Due to the thermo-dynamic design of the expansion valve, the operating parameters of the valve are adversely affected when the insulation is missing or improperly installed. A decrease in cooling efficiency will result.

Scheme 38

1. Locate insulation over expansion valve as illustrated and press together two halves -A- and -B- until they clip into each other.

Note. Depending on engine version, improved access may be obtained by removing front suspension cross brace. Always ensure the expansion valve insulation is properly in place, and is not damaged. Due to the thermo-dynamic design of the expansion valve, the operating parameters of the valve are adversely affected when the insulation is missing or improperly installed. A decrease in cooling efficiency will result. Expansion valve function description. Refer to Refrigerant R134a - Servicing

Refrigerant pipes on compressor, removing and installing

1. Discharge refrigerant circuit. Refer to Refrigerant R134a - Servicing

Scheme 39

1. Remove screws -A-, tightening torque 20 Nm (15 ft lb).
2. Renew O-rings -B- (10.8 mm; 1.8 mm) and -D- (14.3 mm; 2.4 mm).

Note. Refrigerant pipe -C- goes to the condenser. Refrigerant pipe -E- comes from the expansion valve. When installing the refrigerant pipe, make sure that spring pins -F- are properly positioned. Seal off all open refrigerant pipes and connections on compressor.

A/C Compressor - 4-cyl. engine, removing from bracket (refrigerant pipes remain connected)

Special tools, workshop equipment and auxiliary items required

1. VAG 1331 Torque wrench (or 5 - 50 Nm equivalent)

Note. Do not discharge refrigerant circuit and do not disconnect the refrigerant hoses from compressor. Mark running direction of ribbed belt before removing. Ribbed belt could break if allowed to run in reverse direction. When removing compressor, take particular care not to damage power steering pressure switch -F88 (located on power steering pump). If vehicle is equipped with two intercoolers or support brace between left and right long-member, remove connecting pipe between intercoolers and/or support brace.

1. Remove Secondary Air Injection (AIR) Pump Motor -V101-.

Refer to

1. «15 ENGINE - CYLINDER HEAD, VALVETRAIN»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-amu-bea) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA
2. «15 ENGINE - CYLINDER HEAD, VALVETRAIN»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP

1. Remove ribbed belt.

Refer to

1. «13 ENGINE - CRANKSHAFT, CYLINDER BLOCK»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-amu-bea) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA
2. «13 ENGINE - CRANKSHAFT, CYLINDER BLOCK»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP

1. Remove noise insulation and divider between engine compartment and right-hand wheel housing.

Refer to 50 BODY - FRONT .

1. Remove power steering pump from bracket.

Refer to 48 STEERING .

1. Remove bolts -A- , tightening torque 45 Nm (32 ft lb).

Note. Push bushing -B- all the way into the hole on the compressor before reinstalling compressor. After removing compressor, secure to long member (e.g. using a piece of wire). Do not leave suspended from refrigerant lines. Removing and installing compressor bracket

Refer to

1. «13 ENGINE - CRANKSHAFT, CYLINDER BLOCK»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-amu-bea) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA
2. «13 ENGINE - CRANKSHAFT, CYLINDER BLOCK»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP

Scheme 40

Special tools, workshop equipment and auxiliary items required

1. VAG 1331 Torque wrench (or 5 - 50 Nm equivalent)

Note. The compressor bracket and related components can be removed and installed without having to open the refrigerant circuit. Do not discharge refrigerant circuit and do not disconnect the refrigerant hoses from compressor. Mark running direction of ribbed belt before removing. Ribbed belt could break if allowed to run in reverse direction. Removing and installing ribbed belt. Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK .

1 - Ribbed belt tensioner

1. Removing

Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK for 3.2 LITER V6 4V ENGINE MECHANICAL, ENGINE CODE(S): BHE.

1. Ribbed belt, routing. See «Ribbed belt, routing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

2 - Generator (GEN)

1. Removing

Refer to 27 BATTERY, STARTER, GENERATOR, CRUISE CONTROL .

3 - A/C Compressor bracket

1. Part number versions

1. Removing

Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK for 3.2 LITER V6 4V ENGINE MECHANICAL, ENGINE CODE(S): BHE.

4 - Hex socket bolt

1. Tightening torque: 23 Nm

5 - Hex socket bolt

1. Tightening torque: 23 Nm

6 - Power steering pump

1. Removing

Refer to 48 STEERING

7 - A/C Compressor

1. With A/C Clutch -N25
2. Mfr.: Sanden or Zexel
3. A/C Clutch -N25-, sercvicing. Refer to «A/C Clutch -N25-, servicing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)
4. Removing

1. Remove ribbed belt

Refer to 13 ENGINE - CRANKSHAFT, CYLINDER BLOCK .

1. Remove noise insulation and divider between engine compartment and right-hand wheel housing

Refer to 50 BODY - FRONT .

1. Remove power steering pump ( «A/C compressor - 6-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) ) from bracket

Refer to 48 STEERING .

1. Remove support brace between left and right long-member
2. Remove bolts ( «A/C compressor - 6-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) )

Note. Push in mounting bushings prior to reinstalling compressor (same as compressor on 4-cylinder engines).

8 - Hex head bolt

1. Tightening torque: 45 Nm
2. Top bolt must be removed along with compressor (touches long member).

Scheme 41

Note. When installing belt ensure it is correctly seated in pulley and that running direction noted prior to removal is maintained.

1 - Tensioner roller

2 - Generator

3 - A/C Compressor

4 - Power steering pump

5 - Vibration dampener (crankshaft)

6 - Coolant pump

A/C compressor, removing and installing

Note. Mark running direction of ribbed belt before removing. Ribbed belt could break if allowed to run in reverse direction. When removing compressor, take particular care not to damage power steering pressure switch -F88 (located on power steering pump).

1. Discharge refrigerant circuit. Refer to .
2. Remove refrigerant pipes from compressor.
3. 4-cylinder engine - remove compressor from bracket. Refer to «A/C Compressor - 4-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-compressor-4-cyl-engine-removing) .
4. 6-cylinder engine - remove compressor from bracket. Refer to «A/C compressor - 6-cyl. engine, removing from bracket (refrigerant pipes remain connected)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Note. Removed compressor contains refrigerant oil that must be accounted for when replacing compressor. Replacing components. Refer to Refrigerant R134a - Servicing After installing replacement compressor, turn by hand 10 revolutions before activating system for the first time. Procedure when activating the compressor for the first time

1. Start engine with the compressor switched off ("OFF" mode).
2. Wait until the idling speed has stabilized.
3. Switch on the compressor and allow to run for at least 10 minutes with the engine idling.

A/C system control and regulation components in passenger compartment

Note. Upon completion of any A/C system repairs, always check and and erase the Diagnostic Trouble Code (DTC) memory (scan tool function 02), perform basic setting (function 04) and code the A/C control head -E87- (function 07). Checking cooling efficiency. Refer to A/C cooling performance, testing . Refrigerant circuit. Refer to A/C refrigerant system, servicing . All components marked with an asterisk (*) are activated during output Diagnostic Test Mode (DTM) (function 03). Refer to Output Diagnostic Test Mode (DTM) (function 03) . Note different coding possibilities for A/C control head -E87-. Refer to Control Module, coding (function 07) . Electrical testing can be performed on all components marked with a double asterisk (**). Refer to A/C Control Head -E87-, electrical testing . Air distribution system. Refer to Air distribution system (air vents and ducts), servicing . Removing and installing instrument panel cover. Refer to 70 - INTERIOR TRIM .

1 - Instrument panel vent, left

1. Removing and installing. Refer to «Undamaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__undamaged-instrument-panel-vents-removing-and) .

2 - Side window defroster vent

1. Removing and installing.

Refer to 70 - INTERIOR TRIM .

3 - Outside air temperature display -G106- *

1. Outside temperature displayed in °C or in °F depending A/C control head -E87- setting.

Note. If display shows incorrect temperatures, check measured values for temperature sensors. Refer to Read Measuring Value Block (function 08) .

4 - Sunlight photo sensor -G107- **

1. Removing and installing. Refer to «Sunlight photo sensor -G107-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__sunlight-photo-sensor-g107-removing-and) .

5 - Windshield defroster vent

1. Removing and installing. Refer to «Windshield defroster vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__windshield-defroster-vent-removing-and-installing) .

6 - Instrument panel vent, center

1. Removing and installing. Refer to «Damaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__damaged-instrument-panel-vents-removing-and) .

7 - Sender for outlet temperature, floor outlet -G192- **

1. Removing and installing. Refer to «Sender for outlet temperature, floor outlet -G192-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__sender-for-outlet-temperature-floor-outlet) .

8 - Footwell/defroster flap motor -V85-*

1. With motor position sensor -G114-.
2. Removing and installing. Refer to «Footwell/defroster flap motor -V85-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__footwelldefroster-flap-motor-v85-removing-and) .
3. Actuating arm: yellow.

9 - Kickdown switch

1. Depending on vehicle equipment and current vehicle speed, A/C clutch -N25- is deactivated either by the ECM or TCM during full throttle acceleration. Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) .

10 - Footwell vent

1. Removing and installing. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__footwell-ductvent-removing-and-installing) .

11 - Data Link Connector (DLC)

1. Use to connect VAG 1551/1552 or VAS 5051 to perform On Board Diagnostic (OBD) on Automatic Climate Control system. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .

Scheme 42

12 - A/C control head -E87

1. Removing and installing. Refer to «A/C Control Head -E87-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-control-head-e87-removing-and) .

Note. E87- display and operating buttons are illuminated by light emitting diodes (LEDs). Interior temperature sensor fan -V42- * and instrument panel interior temperature sensor -G56- are integrated in -E87-.

13 - Interior temperature sensor fan -V42- * and instrument panel interior temperature sensor -G56

Note. Intake grille for sensor must not be obstructed. Fan and sensor are integrated in -E87- and cannot be replaced separately.

14 - Heating and A/C unit (with heater core and evaporator)

1. Removing and installing. Refer to «Heating and A/C unit (with heater core and evaporator), removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater) .
2. Overview. Refer to «Heating and A/C unit (with heater core and evaporator) mechanical components, overview»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater) .
3. Disassembly and assembly. Refer to «Heating and A/C unit (with heater core and evaporator), disassembly and assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater) .
4. Removing and installing heater core. Refer to «Heater core, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heater-core-removing-and-installing) .

1. Evaporator seal, installing. Refer to «Evaporator seal, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__evaporator-seal-installing) .

15 - Control module for fresh air blower -J126- **

1. Removing and installing. Refer to «Control module for fresh air blower -J126-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__control-module-for-fresh-air-blower) .

16 - Fresh air blower -V2 **

1. Removing and installing. Refer to «Fresh air blower -V2-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__fresh-air-blower-v2-removing-and) .

17 - Instrument panel vent, right

1. Removing and installing. Refer to «Undamaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__undamaged-instrument-panel-vents-removing-and) .

18 - Side window defroster vent

1. Removing and installing.

Refer to 70 - INTERIOR TRIM .

19 - Fresh air intake duct temperature sensor -G89- **

1. Removing and installing. Refer to «Fresh air intake duct temperature sensor -G89-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__fresh-air-intake-duct-temperature-sensor) .

20 - Air flow flap motor -V71- *

1. Actuates air flow flap and fresh air/recirculated air flap.
2. With motor position sensor -G113-.
3. Removing and installing. Refer to «Air flow flap motor -V71-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__air-flow-flap-motor-v71-removing) .

21 - Evaporator housing drain pipe.

1. Checking drain valve. Refer to «Evaporator housing drain valve, checking, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__evaporator-housing-drain-valve-checking-removing) .

22 - Temperature regulator flap motor -V68-*

1. With motor position sensor -G92
2. Removing and installing. Refer to «Temperature regulator flap motor -V68-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__temperature-regulator-flap-motor-v68-removing) .
3. Actuating arm: black or pink.

23 - Central flap motor -V70- *

1. With motor position sensor -G112
2. Removing and installing. Refer to «Central air flap motor -V70-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__central-air-flap-motor-v70-removing) .
3. Actuating arm: green

A/C Control Head -E87-, removing and installing

Note. Always check Diagnostic Trouble Code (DTC) memory before removing -E87-. After replacing -E87-, always: 1) Check coding or enter new coding 2) Perform basic setting 3) Check DTC memory. -E87- temperature display can be switched from °C to °F and back by pressing and holding the "recirculated air" button and at the same time turning the temperature control knob towards "temperature +". If -E87- remains on after the ignition has been switched off, check for short circuit to B+ in the wiring to terminal 1 on connector D (connection for auxiliary heater) according to wiring diagram. If a newly installed A/C control head display flashes for about 2 minutes when the ignition is switched on, code the A/C control head (Scan Tool function 07) and perform basic setting (Scan Tool function 04). If -E87- display does not light up when ignition is switched on, check the voltage supply from terminal 58d (instrument illumination dimmer) to -E87- according to wiring diagram, and also. Refer to A/C Control Head -E87-, electrical testing . If -E87- control buttons do not light up when the vehicle lights are switched on, check voltage supply from terminal 58s (switch illumination) to -E87- according to wiring diagram, and also. Refer to A/C Control Head -E87-, electrical testing . -E87- display and control buttons are illuminated by LEDs and cannot be replaced separately.

Note. A/C Control Head -E87- with part number suffix "A" are installed as a running change during m.y. 2000. -E87- with suffix "A" differs from non suffix version as follows

1. Allocation of ignition key is recognized (as transmitted from the instrument cluster) and displayed in Read Measuring Value Block "009". Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) and «01 ON BOARD DIAGNOSTIC (OBD)»(/audi/tt/8n-1998-2003/remont/cruise-control-systems/#electrical-equipment)

1. The last 4 compressor cut-out conditions that are valid for longer than 20 seconds are saved in memory and displayed in Read Measuring Value Block 011. Refer to «Read Measuring Value Block (function 08)»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__read-measuring-value-block-function-08) .

Removing

1. Remove radio.

Refer to 91 RADIO, TELEPHONE, NAVIGATION, TRIP COMPUTER .

1. Remove two grips from center console.

Refer to 68 - INTERIOR EQUIPMENT .

Scheme 43

1. Remove ashtray and trim -B- for instrument panel center section.

Refer to 68 - INTERIOR EQUIPMENT .

Note. When re-installing trim -B-, note proper positioning of spring clips -C-.

1. Remove screws -A-.
2. Remove A/C control head -E87-.

Scheme 44

1. Press release tabs -arrow- and disconnect electrical connections.
2. Installation is in reverse order of removal.

Interior temperature sensor fan -V42-, removing and installing

1. Remove A/C Control Head -E87-. Refer to «A/C Control Head -E87-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-control-head-e87-removing-and) .

Scheme 45

1. Remove screw -A-.
2. Remove blower assembly from -E87-.

Note. When installing be sure not to apply pressure directly to blower -C-, only to blower housing -B-.

Control module for fresh air blower -J126-, removing and installing

1. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

Scheme 46

1. Disconnect electrical connection -A-.
2. Remove screw -B-.
3. Remove control unit -C- in direction of arrow.

Sender for outlet temperature, floor outlet -G192-, removing and installing

1. Remove storage compartment on driver's side.

Refer to 68 - INTERIOR EQUIPMENT .

Scheme 47

1. Disconnect electrical connection -A-.
2. Turn sender -B- 90 ° and pull out from housing.

Fresh air blower -V2-, removing and installing

1. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove screw clip for foam covering.

Scheme 48

1. Fold foam covering -A- away to one side.
2. Remove screws -B- and cover -C-.

Scheme 49

1. Disconnect electrical connection -A- from fresh air blower.
2. Pull fresh air blower -B- downwards from housing.

Fresh air blower -V2-, separating from from base plate

Note. On vehicles from initial production, the fresh air blower is secured to the base plate by a screw. The base plate may also have a special mat to provide noise insulation.

Scheme 50

1. Remove screw -A-.
2. Remove fresh air blower from base plate -B-.

Note. As a running change in production, the original version will gradually be replaced by one in which the fresh air blower is clipped to the base plate.

Scheme 51

1. Depress retainer clips -A-.
2. Remove fresh air blower from base plate -B-.

Note. When re-installing the blower to the base plate, make sure that mounting lugs -C- are correctly positioned. After installing, make sure that fresh air blower is properly mounted to the base plate. After installing, make sure that fresh air blower is properly seated in the heating and A/C unit housing.

Sunlight photo sensor -G107-, removing and installing

Note. Different defroster vent versions may be installed in production. They differ as follows

1. Versions "1" and "2" can only be removed as a complete unit.

Scheme 52

1. With version "2", damage-free removal may not be possible as the locating fixture may break.

Refer to 70 - INTERIOR TRIM

Scheme 53

1. With version "3" the defroster vent is comprised of two sections (the vent section may be removed separately). With vent removed, photo sensor can be removed as described for version "1")

Refer to 70 - INTERIOR TRIM

Photo sensor with defroster vent version "1', removing

1. Carefully disengage catches -A- between instrument panel and vent using a small screwdriver -B-.
2. Remove vent -C- in direction of -arrow- as illustrated.

Scheme 54

1. Remove screw -A-.
2. Remove photo sensor -B-.
3. Disconnect electrical connection -C-.

Note. If VAG 1551 Scan Tool display shows a constant value of around 90% when reading the measuring value block for A/C control head -E87-, (Display Group 006), check wiring and terminal assignments to -E87- connector -C- according to wiring diagram (wiring may be improperly connected).

Scheme 55

1. Remove two grips from center console.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove ashtray and trim -A- for instrument panel center section.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove caps -B-.
2. Remove screws -C-.
3. Remove trim panels -A- and -D-.

Scheme 56

1. Remove footwell vent -E- towards driver's side -arrow-.

Footwell/defroster flap motor -V85-, removing and installing

1. Remove driver's storage compartment.

Refer to 68 - INTERIOR EQUIPMENT .

Scheme 57

1. Disconnect electrical connection -A-.
2. Remove screws -B- (3x).
3. Disengage actuating arm -C- and remove motor.

Notes on installation

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. When installing motor, make sure actuating arm -C- is properly aligned and installed.
3. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

Temperature regulator flap motor -V68-, removing and installing

1. Remove footwell vent. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Scheme 58

1. Disconnect electrical connection -A-.
2. Remove bolts -B- (3x).
3. Disengage actuating arm -C- and remove motor.

Notes on installation

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. When installing motor, make sure actuating arm -C- is properly aligned and installed.
3. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

Central air flap motor -V70-, removing and installing

1. Remove footwell vent. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Scheme 59

1. Disconnect electrical connection -A-.
2. Remove screws -B- (3x).
3. Disengage actuating arm -C- and remove motor.

Notes on installation

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. When installing motor, make sure actuating arm -C- is properly aligned and installed.
3. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

Fresh air intake duct temperature sensor -G89-, removing and installing

1. Remove dust and pollen filter. Refer to «Dust and pollen filter, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__dust-and-pollen-filter-removing-and) .
2. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

Scheme 60

1. Reach into the intake housing and rotate temperature sensor -A- 90 °.
2. Reach between heating and A/C unit and A-pillar and remove temperature sensor from intake housing -arrow- with electrical connector -C- still attached.

Note. If the temperature sensor is difficult to rotate, carefully apply silicone spray to the contact surface of rubber grommet -B- on the intake housing. Checking -G89-. Refer to A/C Control Head -E87-, electrical testing .

Air flow flap motor -V71-, removing and installing

Note. V71- operates the air flow flap and fresh/recirculated air flap.

1. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

Scheme 61

1. Carefully detach actuating arm -A- (for air flow flap) with screwdriver.

Scheme 62

1. Remove bolt -A-.
2. Disconnect electrical connection -C-.
3. Rotate motor downwards in direction -arrow- and pull out of shaft for fresh/recirculated air flap -B-.

Notes on installation

1. Replacement motors are supplied set to "recirculated air" mode. To facilitate installation, first connect motor to vehicle electrical system and centralize actuating arm. This is done by switching on the ignition and pressing the "recirculated air" button on the A/C control head to change setting of motor. With the actuating arm centralized, the fresh/recirculated air flap does not touch the limit stops, and the motor can be installed more easily.

Scheme 63

1. First insert motor into shaft of fresh/recirculated air flap -B-. Then rotate in direction of -arrow-, making sure that lug -D- fits into slot -C-.

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

Heating and A/C unit (with heater core and evaporator), removing and installing

1. Discharge refrigerant circuit. Refer to Refrigerant R134a - Servicing
2. Remove dust and pollen filter. Refer to «Dust and pollen filter, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__dust-and-pollen-filter-removing-and) .
3. Switch ignition on.
4. Press "recirculated air" button on A/C control head -E87-.

Scheme 64

1. Wait until air flow flap -A- closes (fresh/recirculated air flap moves to "recirculated air" position).
2. Switch off ignition with the air flow flap closed.

1. Release pressure in cooling system by carefully and slowly opening cap on coolant expansion tank.

Note. Depending on engine version, improved access may be obtained by removing front suspension cross brace.

Scheme 65

1. Using tools 3094, clamp off both coolant hoses for heater core at a point between the engine and connections -A-.
2. Remove spring clamps -B- and detach coolant hoses.

Note. Example illustrated: Heater core configuration without quick-connect coupling

Coolant hose -C- = supply hose from cylinder head (marked with letter "V".

Coolant hose -D- = return hose to water pump (marked with letter "R")

Heater core/coolant flow direction configurations

Note. Depending on engine and heater core configuration, various coolant hose connection types with coolant flow direction are installed in production. Coolant hoses must not be interchanged when installing. Coolant flow direction is indicated on inlet and outlet tubes of heater core (may or may not be visible when installed, but can be felt).

Scheme 66

1. Heater core configuration with quick-connect coupling version "1"

Coolant hose -A- = supply hose from cylinder head

Coolant hose -B- = return hose to water pump

Coolant flow direction indicated on heater core tubes -C- (visible when installed)

Scheme 67

1. Heater core configuration with quick-disconnect coupling version "2"

Coolant hose -A- = supply hose from cylinder head

Coolant hose -B- = return hose to water pump

1. Bleeding cooling system. Refer to «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-amu-bea) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP .
2. Bleeding cooling system. Refer to «19 ENGINE - COOLING SYSTEM»(ref-276269-S03261728742008010300000) for 3.2 LITER V6 4V ENGINE MECHANICAL, ENGINE CODE(S): BHE.

Scheme 68

1. Place suitable container under connection -B- and carefully expel coolant from heater core (using compressed air) through connection -A-.

Note. Depending on engine/heater core configuration, pay attention to coolant flow direction through heater core. Only blow thorough heater core in direction of coolant flow as indicated on heater core inlet and outlet tubes. Heater core configuration without quick-connect couplings illustrated here.

1. Remove expansion valve. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .

Scheme 69

1. Seal off refrigerant pipes and open connections -A- and -B- on evaporator.
2. Remove hex nuts with washers -C-, tightening torque 15 Nm (11 ft lb).

Note. Washers for hex nuts should be fitted with seals.

Scheme 70

1. Fold back pre-punched flaps -A- on insulation mat and remove hex nuts and washers -B- underneath, tightening torque 15 Nm (11 ft lb).
2. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove storage compartment on driver's side, dash panel center section and instrument panel.

Refer to 70 - INTERIOR TRIM .

1. Remove center console (complete).

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove footwell vent. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Scheme 71

1. Remove air duct -A- (leading to defroster vent).
2. Remove front passenger's airbag unit (complete) together with left-hand bracket for instrument panel cross member.

Refer to 69 - PASSENGER PROTECTION - AIRBAGS, SEAT BELTS .

1. Disconnect Ground (GND) connection between heating and A/C unit and ground connection at bottom of right A-pillar.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

1. Cover all exposed connectors and the A/C air ducts (protection from drilling remains).

Scheme 72

1. Drill two 7 mm holes in instrument panel support, one at each of the welding points marked -A- (drill through both layers).
2. Saw through support at -B- (e.g. using body saw V.A.G 1523 A or equivalent).

Scheme 73

1. Bend section -A- of support to one side in direction of -arrow- (or break off completely) along break line -B-.

1. Unplug all electrical wiring connections between vehicle systems and the heating and A/C unit.

Scheme 74

1. Remove unit towards passenger side -arrow-.

Notes on installation

1. Before installing, check all gaskets and seals on the heating and A/C unit for damage and replace if necessary.
2. When installing, check seal at intake housing. Seal must face body side.

Scheme 75

1. Replace seal -A- and ensure it is properly seated against contact surface -C-.
2. Reattach coolant hoses according to coolant flow direction indicated on heater core. Reference heater core/coolant flow configurations. Refer to «Heater core/coolant flow direction configurations»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Heater core configuration without quick-connect couplings illustrated here (coolant flow direction -arrow B-).
4. After assembling, all cable ties which were removed in order to take out the air conditioner must be refitted in their original positions.

1. Replace both O-rings for refrigerant pipes and expansion valve.
2. Install refrigerant pipes free of stress.

Notes on installation, continued

1. Ensure evaporator drain pipe and valve are properly seated.

Scheme 76

1. Replace gasket and ensure it is properly seated on the evaporator connecting flange.

After installing the heating and A/C unit, proceed as follows

Scheme 77

1. Bend section -A- of the instrument panel support back into position.
2. Bolt section -B- (which is welded to section -A-) to section -C- of the support with two bolts -D- (for example, M6 x 10 bolts) and two combi nuts -E-.

Note. When inserting bolts -D-, make sure they do not contact the bracket for the airbag unit.

Scheme 78

1. Remove heating and A/C unit. Refer to «Heating and A/C unit (with heater core and evaporator), removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Remove screws -C-.
3. Depress tabs -B- and pull (lift) heater core -A- from housing.

Notes on installing

1. When installing heater core, always secure it in the heater flap housing with two suitable screws -C- (e.g. self-tapping screws, 3.2 x 20 mm). This also applies even if the heat exchanger was originally only clipped in place.
2. The heater core is installed in the heater flap housing without an all-round seal.

1. Replace seal -A- and ensure it is properly seated against contact surface -C-.
2. Reattach coolant hoses according to coolant flow direction indicated on heater core. Reference heater core/coolant flow configurations. Refer to «Heater core/coolant flow direction configurations»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Heater core configuration without quick-connect couplings illustrated here (coolant flow direction -arrow B-).

Scheme 79

1 - Heater core

1. Removing and installing. Refer to «Heater core, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

2 - Seal

1. Always replace
2. Seals heater core from engine compartment.

3 - Mounting flange

4 - Screw

5 - Evaporator housing seal

1. Always replace
2. Seals refrigerant pipes from engine compartment.
3. Location. See «Evaporator housing seal, location»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__evaporator-housing-seal-location) .

6 - Defroster duct

1. Removing and installing. Refer to «Defroster vent air duct, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__defroster-vent-air-duct-removing-and) .

7 - Tensioning strap

1. Must be installed correctly. See «Tensioning strap, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__tensioning-strap-installing) .

8 - Climate control system wiring harness

1. When installing, ensure proper clearance to moving parts. See «Installing wiring harness for air conditioner»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__installing-wiring-harness-for-air-conditioner) .

9 - Kick panel

1. Secured with tensioning strap and screw clips.

10 - Screw clip

11 - Footwell duct/vent

1. Removing and installing. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

12 - Heating and A/C unit

1. With electrical components
2. Electrical components, overview. Refer to «Heating and A/C unit (with heater core and evaporator) electrical components, overview»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater) .
3. Removing and installing. Refer to «Heating and A/C unit (with heater core and evaporator), removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning)
4. Disassembly and assembly. Refer to «Heating and A/C unit (with heater core and evaporator), disassembly and assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater) .

Scheme 80

Note. Ensure tensioning strap -A- is installed and located in the correct positions around the housing. The tensioning strap also holds the cover on the evaporator housing.

Scheme 81

Note. Wiring harness -A- must be positioned so that it cannot come into contact with any moving parts (e.g. actuating arms -B- for positioning motors). Secure wiring harness with suitable tie wraps to prevent it from coming loose.

Scheme 82

Note. Always replace seal -A- , and install securely in recess around the evaporator housing.

Scheme 83

1 - Heating and A/C unit

1. Disassembly and assembly. Refer to «Heating and A/C unit (with heater core and evaporator), disassembly and assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater) .

2 - Fresh air intake duct temperature sensor -G89

1. Removing and installing. Refer to «Fresh air intake duct temperature sensor -G89-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

3 - Air flow flap motor -V71

1. Operates the air flow flap and fresh/recirculated air flap.
2. With motor position sensor -G113-.
3. Removing and installing. Refer to «Air flow flap motor -V71-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

4 - Screw

5 - Actuating arm

1. To air flap

6 - Control module for fresh air blower -J126

1. Removing and installing. Refer to «Control module for fresh air blower -J126-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__control-module-for-fresh-air-blower) .

7 - Screw

8 - Fresh air blower -V2

1. Removing and installing. Refer to «Fresh air blower -V2-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__fresh-air-blower-v2-removing-and) .

9 - Mounting plate

10 - Screw

11 - Noise insulation

1. Not installed on all vehicles.

12 - Screw

13 - Cover

14 - Screw

15 - Screw

16 - Temperature regulator flap motor -V68

1. With motor position sensor -G92-.
2. Removing and installing. Refer to «Temperature regulator flap motor -V68-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Actuating arm: black or pink.

17 - Actuating arm

18 - Central air flap motor -V70

1. With motor position sensor -G112-.
2. Removing and installing. Refer to «Central air flap motor -V70-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Actuating arm: green.

19 - Actuating arm

20 - Footwell/defroster flap motor -V85

1. With motor position sensor -G114-.
2. Removing and installing. Refer to «Footwell/defroster flap motor -V85-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Actuating arm: yellow.

21 - Actuating arm

22 - Mounting bracket for -V85

23 - Sender for outlet temperature, floor outlet -G192

1. Removing and installing. Refer to «Sender for outlet temperature, floor outlet -G192-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__sender-for-outlet-temperature-floor-outlet) .

Scheme 84

1 - Seal

1. Seals intake duct against air intake plenum.
2. Check and replace if damaged.

2 - Air flap

1. Lightly lubricate hinge pivots with grease G 052 745 A3 or equivalent.

3 - Grommet

4 - Lever

5 - Air distribution housing, upper part

1. Assembly. See «Air distribution housing, assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__air-distribution-housing-assembly) .
2. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__refrigerant-pipe-seal-at-evaporator-installing) .

6 - Fresh/recirculation flap

1. Lightly lubricate hinge pivots with grease G 052 745 A3 or equivalent.

7 - Evaporator

1. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__refrigerant-pipe-seal-at-evaporator-installing) .
2. Installing seal. See «Evaporator seal, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__evaporator-seal-installing) .
3. Removed evaporator contains refrigerant oil that must be accounted for in refrigerant system when evaporator replacement is necessary. Refer to Refrigerant R134a - Servicing ("Replacing components").

8 - Pivot bushing

1. Lightly lubricate with grease G 052 745 A3 or equivalent.

9 - Air distribution housing, lower part

1. Assembly. See «Air distribution housing, assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__air-distribution-housing-assembly) .
2. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__refrigerant-pipe-seal-at-evaporator-installing) .

10 - Screw

11 - Pivot bushing

1. Lightly lubricate with grease G 052 745 A3 or equivalent.

12 - Central flap lever

13 - Screw

14 - Temperature flap lever

15 - Central flap

1. Note installation position (shorter section of flap faces up).

16 - Footwell/defroster flap

1. Lightly lubricate hinge pivots with grease G 052 745 A3 or equivalent.

17 - Temperature flap

18 - Seal

1. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__refrigerant-pipe-seal-at-evaporator-installing) .

19 - Threaded bracket

20 - O-Ring

1. Removing and installing. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .

21 - O-Ring

1. Removing and installing. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .

22 - Expansion valve

1. Removing and installing refrigerant pipes. Refer to «Refrigerant pipes on expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__refrigerant-pipes-on-expansion-valve-removing) .
2. Removing and installing. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .
3. Removing and installing insulation. Refer to «Expansion valve insulation, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

23 - Bolt

1. Tightening torque: 8 Nm (71 in lb).

24 - Air deflector

Scheme 85

1. Secure both halves of the housing with screws -A- at locations (example) -B-.

Refrigerant pipe seal at evaporator, installing

Evaporator refrigerant pipes -C- must be completely encapsulated by seal -A- between both halves of the air distribution housing -B-.

1. After securing both halves of the housing, apply silicone seal as necessary at any open locations. Housing must be completely sealed against entry of hot air from the engine compartment or warm air from the passenger compartment, otherwise, cooling efficiency will be affected.

Scheme 86

1. Evaporator -A- must be sealed (top and sides with gasket -B-) against the air distribution housing

Note. A gap must remain in the seal on the bottom of the evaporator to allow water to drain.

Air distribution system (air vents and ducts), servicing

Note. Air is extracted from the passenger compartment via two air extraction vents located in the luggage compartment, left and right behind the rear bumper. Refer to Air extraction vents, checking .

Scheme 87

1 - Instrument panel

1. Removing and installing

Refer to 70 - INTERIOR TRIM .

2 - Side window defroster vent

1. Removing and installing

Refer to 70 - INTERIOR TRIM .

3 - Instrument panel vent, left

1. Removing and installing undamaged vent. Refer to «Undamaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__undamaged-instrument-panel-vents-removing-and) .
2. Removing and installing damaged vent. Refer to «Damaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__damaged-instrument-panel-vents-removing-and) .

4 - Instrument panel vent, center

1. Removing and installing undamaged vent. Refer to «Undamaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__undamaged-instrument-panel-vents-removing-and) .
2. Removing and installing damaged vent. Refer to «Damaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__damaged-instrument-panel-vents-removing-and) .

5 - Instrument panel vent, right

1. Removing and installing undamaged vent. Refer to «Undamaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__undamaged-instrument-panel-vents-removing-and) .
2. Removing and installing damaged vent. Refer to «Damaged instrument panel vents, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__damaged-instrument-panel-vents-removing-and) .

6 - Windshield defroster vent

1. Removing and installing. Refer to «Windshield defroster vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__windshield-defroster-vent-removing-and-installing) .

7 - Screw

8 - Air duct for center instrument panel vents

1. Attached to instrument panel with retainer clips.

9 - Connecting piece for instrument panel vents

1. Clipped to air ducts.

10 - Air duct for left and right vents

1. Attached to instrument panel with retainer clips.

11 - Air duct to defroster vent

1. Removing and installing. Refer to «Defroster vent air duct, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__defroster-vent-air-duct-removing-and) .

12 - Air distribution box (part of heating and A/C unit)

1. Removing and installing heater core. Refer to «Heater core, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Removing and installing heating and A/C unit. Refer to «Heating and A/C unit (with heater core and evaporator), removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Scheme 88

1. Bend a piece of wire (3 mm diameter) as shown.

1. Distance x = 6 mm.

Scheme 89

1. Insert both hooks -A- into vent as illustrated and pull evenly on both tools to remove vent.

Note. To remove undamaged vents that will later be re-installed, press the vent out of the instrument panel from behind. Refer to Undamaged instrument panel vents, removing and installing . Do not use hooks -A- as these could damage the vent.

Undamaged instrument panel vents, removing and installing

Note. To remove an undamaged vent that will later be re-installed, press vent out of the instrument panel from behind. Removing it from the front of the instrument panel could damage the vent. To remove a damaged vent, use hooks -A-. Refer to Damaged instrument panel vents, removing and installing .

1. To gain access to the left vent, first remove storage compartment on the driver's side.

Refer to 68 - INTERIOR EQUIPMENT .

1. To gain access to the right- vent, first remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. To gain access to the center vents, first remove the center section of the instrument panel and also the switch panel.

Refer to 68 - INTERIOR EQUIPMENT .

Scheme 90

1. Reach behind instrument panel from below and push vent -A- from opening in instrument panel.

Note. When installing, make sure vent is the oriented properly (i.e. with tabs -B- towards bottom). When installing, make sure locating piece -A- is inserted in slot -B- on instrument panel.

Windshield defroster vent, removing and installing

1. Carefully disengage catches -A- between instrument panel and vent using a small screwdriver -B-.
2. Remove vent -C- as illustrated.

Defroster vent air duct, removing and installing

1. Remove instrument panel.

Refer to 70 - INTERIOR TRIM .

1. Lift out air duct -A-.

Scheme 91

1. Lift air intake plenum cover section -A-.
2. Push back tabs -B-.
3. Remove dust and pollen filter element from housing.

Note. To prevent water from running onto dust and pollen filter and into the heating system, the air intake plenum cover and wind deflector must be properly installed. Air intake plenum cover section -A- must not contact dust and pollen filter. Dust and pollen filter element should be replaced at regular intervals. Refer to 01 MAINTENANCE Dust and pollen filter must be re-installed correctly in frame -B-. Arrows -A- marked on frame indicate air flow direction through filter element.

Scheme 92

Sealing lips -B- on vent frame -A- must be able to move freely and close by themselves.

Note. Illustration shows location of extraction vents behind rear bumper. Remove rear bumper to access vents. Refer to 63 BUMPERS . Vehicle is fitted with two air extraction vents (left and right) for forced air extraction.

To ensure proper air extraction from passenger compartment, check the following

Scheme 93

1. Ventilation slits -A- in luggage compartment trim must not be obstructed.
2. Air ducts in the luggage compartment trim must not be covered.
3. Air flow through vent frame -B- must not be obstructed by objects in the luggage compartment.

Footwell duct/vent, removing and installing

1. Remove two grips from center console.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove ashtray and trim -A- for instrument panel center section.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove caps -B-.
2. Remove screws -C-.
3. Remove trim panels -A- and -D-.

1. Remove footwell vent -E- towards driver's side -arrow-.

1. Remove driver's storage compartment.

Refer to 68 - INTERIOR EQUIPMENT .

1. Disconnect electrical connection -A-.
2. Remove screws -B- (3x).
3. Disengage actuating arm -C- and remove motor.

Notes on installation

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. When installing motor, make sure actuating arm -C- is properly aligned and installed.
3. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

1. Remove footwell vent. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__footwell-ductvent-removing-and-installing) .

1. Disconnect electrical connection -A-.
2. Remove bolts -B- (3x).
3. Disengage actuating arm -C- and remove motor.

Notes on installation

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. When installing motor, make sure actuating arm -C- is properly aligned and installed.
3. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

1. Remove footwell vent. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__footwell-ductvent-removing-and-installing) .

1. Disconnect electrical connection -A-.
2. Remove screws -B- (3x).
3. Disengage actuating arm -C- and remove motor.

Notes on installation

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. When installing motor, make sure actuating arm -C- is properly aligned and installed.
3. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

1. Remove dust and pollen filter. Refer to «Dust and pollen filter, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. Reach into the intake housing and rotate temperature sensor -A- 90 °.
2. Reach between heating and A/C unit and A-pillar and remove temperature sensor from intake housing -arrow- with electrical connector -C- still attached.

Note. If the temperature sensor is difficult to rotate, carefully apply silicone spray to the contact surface of rubber grommet -B- on the intake housing. Checking -G89-. Refer to A/C Control Head -E87-, electrical testing .

Note. V71- operates the air flow flap and fresh/recirculated air flap.

1. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. Carefully detach actuating arm -A- (for air flow flap) with screwdriver.

1. Remove bolt -A-.
2. Disconnect electrical connection -C-.
3. Rotate motor downwards in direction -arrow- and pull out of shaft for fresh/recirculated air flap -B-.

Notes on installation

1. Replacement motors are supplied set to "recirculated air" mode. To facilitate installation, first connect motor to vehicle electrical system and centralize actuating arm. This is done by switching on the ignition and pressing the "recirculated air" button on the A/C control head to change setting of motor. With the actuating arm centralized, the fresh/recirculated air flap does not touch the limit stops, and the motor can be installed more easily.

1. First insert motor into shaft of fresh/recirculated air flap -B-. Then rotate in direction of -arrow-, making sure that lug -D- fits into slot -C-.

1. After installing, always carry out On Board Diagnostic (OBD) on Climate control. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__vag-1551-scan-tool-st-vas) .
2. Route electrical wiring harness so that it cannot come into contact with any moving parts like the actuating arm on the motor or other.

1. Discharge refrigerant circuit. Refer to «A/C refrigerant system, discharging»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-refrigerant-system-discharging) .
2. Remove dust and pollen filter. Refer to «Dust and pollen filter, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Switch ignition on.
4. Press "recirculated air" button on A/C control head -E87-.

1. Wait until air flow flap -A- closes (fresh/recirculated air flap moves to "recirculated air" position).
2. Switch off ignition with the air flow flap closed.

1. Release pressure in cooling system by carefully and slowly opening cap on coolant expansion tank.

Note. Depending on engine version, improved access may be obtained by removing front suspension cross brace.

1. Using tools 3094, clamp off both coolant hoses for heater core at a point between the engine and connections -A-.
2. Remove spring clamps -B- and detach coolant hoses.

Note. Example illustrated: Heater core configuration without quick-connect coupling

Coolant hose -C- = supply hose from cylinder head (marked with letter "V")

Coolant hose -D- = return hose to water pump (marked with letter "R")

Note. Depending on engine and heater core configuration, various coolant hose connection types with coolant flow direction are installed in production. Coolant hoses must not be interchanged when installing. Coolant flow direction is indicated on inlet and outlet tubes of heater core (may or may not be visible when installed, but can be felt).

1. Heater core configuration with quick-connect coupling version "1"

Coolant hose -A- = supply hose from cylinder head

Coolant hose -B- = return hose to water pump

Coolant flow direction indicated on heater core tubes -C- (visible when installed)

1. Heater core configuration with quick-disconnect coupling version "2"

Coolant hose -A- = supply hose from cylinder head

Coolant hose -B- = return hose to water pump

1. Bleeding cooling system. Refer to «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-amu-bea) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): AMU, BEA «19 ENGINE - COOLING SYSTEM»(/audi/tt/8n-1998-2003/remont/blowers-superchargers-turbochargers/#18l-4-cyl-5v-turbo-engine-mechanical-engine-codes-atc-awp) for 1.8 LITER 4-CYL. 5V TURBO ENGINE MECHANICAL, ENGINE CODE(S): ATC, AWP .
2. Bleeding cooling system. Refer to «19 ENGINE - COOLING SYSTEM»(ref-276269-S03261728742008010300000) for 3.2 LITER V6 4V ENGINE MECHANICAL, ENGINE CODE(S): BHE.

1. Place suitable container under connection -B- and carefully expel coolant from heater core (using compressed air) through connection -A-.

Note. Depending on engine/heater core configuration, pay attention to coolant flow direction through heater core. Only blow thorough heater core in direction of coolant flow as indicated on heater core inlet and outlet tubes. Heater core configuration without quick-connect couplings illustrated here.

1. Remove expansion valve. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .

1. Seal off refrigerant pipes and open connections -A- and -B- on evaporator.
2. Remove hex nuts with washers -C-, tightening torque 15 Nm (11 ft lb).

Note. Washers for hex nuts should be fitted with seals.

1. Fold back pre-punched flaps -A- on insulation mat and remove hex nuts and washers -B- underneath, tightening torque 15 Nm (11 ft lb).
2. Remove glove box.

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove storage compartment on driver's side, dash panel center section and instrument panel.

Refer to 70 - INTERIOR TRIM .

1. Remove center console (complete).

Refer to 68 - INTERIOR EQUIPMENT .

1. Remove footwell vent. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__footwell-ductvent-removing-and-installing) .

1. Remove air duct -A- (leading to defroster vent).
2. Remove front passenger's airbag unit (complete) together with left-hand bracket for instrument panel cross member.

Refer to 69 - PASSENGER PROTECTION - AIRBAGS, SEAT BELTS .

1. Disconnect Ground (GND) connection between heating and A/C unit and ground connection at bottom of right A-pillar.

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations.

1. Cover all exposed connectors and the A/C air ducts (protection from drilling remains).

1. Drill two 7 mm holes in instrument panel support, one at each of the welding points marked -A- (drill through both layers).
2. Saw through support at -B- (e.g. using body saw V.A.G 1523 A or equivalent).

1. Bend section -A- of support to one side in direction of -arrow- (or break off completely) along break line -B-.

1. Unplug all electrical wiring connections between vehicle systems and the heating and A/C unit.

1. Remove unit towards passenger side -arrow-.

Notes on installation

1. Before installing, check all gaskets and seals on the heating and A/C unit for damage and replace if necessary.
2. When installing, check seal at intake housing. Seal must face body side.

1. Replace seal -A- and ensure it is properly seated against contact surface -C-.
2. Reattach coolant hoses according to coolant flow direction indicated on heater core. Reference heater core/coolant flow configurations. Refer to «Heater core/coolant flow direction configurations»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heater-corecoolant-flow-direction-configurations) .
3. Heater core configuration without quick-connect couplings illustrated here (coolant flow direction -arrow B-).
4. After assembling, all cable ties which were removed in order to take out the air conditioner must be refitted in their original positions.

1. Replace both O-rings for refrigerant pipes and expansion valve.
2. Install refrigerant pipes free of stress.

Notes on installation, continued

1. Ensure evaporator drain pipe and valve are properly seated.

1. Replace gasket and ensure it is properly seated on the evaporator connecting flange.

After installing the heating and A/C unit, proceed as follows

1. Bend section -A- of the instrument panel support back into position.
2. Bolt section -B- (which is welded to section -A-) to section -C- of the support with two bolts -D- (for example, M6 x 10 bolts) and two combi nuts -E-.

Note. When inserting bolts -D-, make sure they do not contact the bracket for the airbag unit.

Heater core, removing and installing

1. Remove heating and A/C unit. Refer to «Heating and A/C unit (with heater core and evaporator), removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater) .
2. Remove screws -C-.
3. Depress tabs -B- and pull (lift) heater core -A- from housing.

Notes on installing

1. When installing heater core, always secure it in the heater flap housing with two suitable screws -C- (e.g. self-tapping screws, 3.2 x 20 mm). This also applies even if the heat exchanger was originally only clipped in place.
2. The heater core is installed in the heater flap housing without an all-round seal.

1. Replace seal -A- and ensure it is properly seated against contact surface -C-.
2. Reattach coolant hoses according to coolant flow direction indicated on heater core. Reference heater core/coolant flow configurations. Refer to «Heater core/coolant flow direction configurations»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heater-corecoolant-flow-direction-configurations) .
3. Heater core configuration without quick-connect couplings illustrated here (coolant flow direction -arrow B-).

Heating and A/C unit (with heater core and evaporator) mechanical components, overview

1 - Heater core

1. Removing and installing. Refer to «Heater core, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heater-core-removing-and-installing) .

2 - Seal

1. Always replace
2. Seals heater core from engine compartment.

3 - Mounting flange

4 - Screw

5 - Evaporator housing seal

1. Always replace
2. Seals refrigerant pipes from engine compartment.
3. Location. See «Evaporator housing seal, location»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

6 - Defroster duct

1. Removing and installing. Refer to «Defroster vent air duct, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

7 - Tensioning strap

1. Must be installed correctly. See «Tensioning strap, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

8 - Climate control system wiring harness

1. When installing, ensure proper clearance to moving parts. See «Installing wiring harness for air conditioner»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

9 - Kick panel

1. Secured with tensioning strap and screw clips.

10 - Screw clip

11 - Footwell duct/vent

1. Removing and installing. Refer to «Footwell duct/vent, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__footwell-ductvent-removing-and-installing) .

12 - Heating and A/C unit

1. With electrical components
2. Electrical components, overview. Refer to «Heating and A/C unit (with heater core and evaporator) electrical components, overview»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Removing and installing. Refer to «Heating and A/C unit (with heater core and evaporator), removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__heating-and-ac-unit-with-heater)
4. Disassembly and assembly. Refer to «Heating and A/C unit (with heater core and evaporator), disassembly and assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

Tensioning strap, installing

Note. Ensure tensioning strap -A- is installed and located in the correct positions around the housing. The tensioning strap also holds the cover on the evaporator housing.

Installing wiring harness for air conditioner

Note. Wiring harness -A- must be positioned so that it cannot come into contact with any moving parts (e.g. actuating arms -B- for positioning motors). Secure wiring harness with suitable tie wraps to prevent it from coming loose.

Evaporator housing seal, location

Note. Always replace seal -A- , and install securely in recess around the evaporator housing.

Heating and A/C unit (with heater core and evaporator) electrical components, overview

1 - Heating and A/C unit

1. Disassembly and assembly. Refer to «Heating and A/C unit (with heater core and evaporator), disassembly and assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

2 - Fresh air intake duct temperature sensor -G89

1. Removing and installing. Refer to «Fresh air intake duct temperature sensor -G89-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__fresh-air-intake-duct-temperature-sensor) .

3 - Air flow flap motor -V71

1. Operates the air flow flap and fresh/recirculated air flap.
2. With motor position sensor -G113-.
3. Removing and installing. Refer to «Air flow flap motor -V71-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__air-flow-flap-motor-v71-removing) .

4 - Screw

5 - Actuating arm

1. To air flap

6 - Control module for fresh air blower -J126

1. Removing and installing. Refer to «Control module for fresh air blower -J126-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__control-module-for-fresh-air-blower) .

7 - Screw

8 - Fresh air blower -V2

1. Removing and installing. Refer to «Fresh air blower -V2-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__fresh-air-blower-v2-removing-and) .

9 - Mounting plate

10 - Screw

11 - Noise insulation

1. Not installed on all vehicles.

12 - Screw

13 - Cover

14 - Screw

15 - Screw

16 - Temperature regulator flap motor -V68

1. With motor position sensor -G92-.
2. Removing and installing. Refer to «Temperature regulator flap motor -V68-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__temperature-regulator-flap-motor-v68-removing) .
3. Actuating arm: black or pink.

17 - Actuating arm

18 - Central air flap motor -V70

1. With motor position sensor -G112-.
2. Removing and installing. Refer to «Central air flap motor -V70-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__central-air-flap-motor-v70-removing) .
3. Actuating arm: green.

19 - Actuating arm

20 - Footwell/defroster flap motor -V85

1. With motor position sensor -G114-.
2. Removing and installing. Refer to «Footwell/defroster flap motor -V85-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__footwelldefroster-flap-motor-v85-removing-and) .
3. Actuating arm: yellow.

21 - Actuating arm

22 - Mounting bracket for -V85

23 - Sender for outlet temperature, floor outlet -G192

1. Removing and installing. Refer to «Sender for outlet temperature, floor outlet -G192-, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__sender-for-outlet-temperature-floor-outlet) .

Heating and A/C unit (with heater core and evaporator), disassembly and assembly

1 - Seal

1. Seals intake duct against air intake plenum.
2. Check and replace if damaged.

2 - Air flap

1. Lightly lubricate hinge pivots with grease G 052 745 A3 or equivalent.

3 - Grommet

4 - Lever

5 - Air distribution housing, upper part

1. Assembly. See «Air distribution housing, assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

6 - Fresh/recirculation flap

1. Lightly lubricate hinge pivots with grease G 052 745 A3 or equivalent.

7 - Evaporator

1. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Installing seal. See «Evaporator seal, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
3. Removed evaporator contains refrigerant oil that must be accounted for in refrigerant system when evaporator replacement is necessary. Refer to «For leaky or damaged components (except for the compressor and receiver drier) there is still refrigerant oil in the system component that must be accounted for when replacing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__for-leaky-or-damaged-components-except) . Also. Refer to «A/C refrigerant system, replacing components»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__ac-refrigerant-system-replacing-components) ("Replacing components").

8 - Pivot bushing

1. Lightly lubricate with grease G 052 745 A3 or equivalent.

9 - Air distribution housing, lower part

1. Assembly. See «Air distribution housing, assembly»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .
2. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

10 - Screw

11 - Pivot bushing

1. Lightly lubricate with grease G 052 745 A3 or equivalent.

12 - Central flap lever

13 - Screw

14 - Temperature flap lever

15 - Central flap

1. Note installation position (shorter section of flap faces up).

16 - Footwell/defroster flap

1. Lightly lubricate hinge pivots with grease G 052 745 A3 or equivalent.

17 - Temperature flap

18 - Seal

1. Installing seal at refrigerant pipes. See «Refrigerant pipe seal at evaporator, installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

19 - Threaded bracket

20 - O-Ring

1. Removing and installing. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .

21 - O-Ring

1. Removing and installing. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .

22 - Expansion valve

1. Removing and installing refrigerant pipes. Refer to «Refrigerant pipes on expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__refrigerant-pipes-on-expansion-valve-removing) .
2. Removing and installing. Refer to «Expansion valve, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning__expansion-valve-removing-and-installing) .
3. Removing and installing insulation. Refer to «Expansion valve insulation, removing and installing»(/audi/tt/8n-1998-2003/remont/ac-compressor/#heating-air-conditioning) .

23 - Bolt

1. Tightening torque: 8 Nm (71 in lb).

24 - Air deflector

Air distribution housing, assembly

1. Secure both halves of the housing with screws -A- at locations (example) -B-.

Evaporator refrigerant pipes -C- must be completely encapsulated by seal -A- between both halves of the air distribution housing -B-.

1. After securing both halves of the housing, apply silicone seal as necessary at any open locations. Housing must be completely sealed against entry of hot air from the engine compartment or warm air from the passenger compartment, otherwise, cooling efficiency will be affected.

Evaporator seal, installing

1. Evaporator -A- must be sealed (top and sides with gasket -B-) against the air distribution housing

Note. A gap must remain in the seal on the bottom of the evaporator to allow water to drain.

A/C cooling performance, testing