Heating & Air Conditioning: Diagnosis Audi TT 8N facelift

Automatic Climate Control system, On Board Diagnostic (OBD)

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

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)»(ref-276291-S31381018642008010300000) . Also see «96 LIGHTS, SWITCHES - INTERIOR, ANTI-THEFT»(ref-276293-S29109524092008010300000) .
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)»(ref-276291-S31381018642008010300000) .

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»(ref-276291-S07751104692008010300000) .
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»(ref-276291-S07751104692008010300000) .
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)»(ref-276291-S41678913222008010300000) .
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)»(ref-276291-S31381018642008010300000) .
2. Perform output Diagnostic Test Mode (DTM) (function 03). Refer to «Output Diagnostic Test Mode (DTM) (function 03)»(ref-276291-S06596186142008010300000) .
3. Check A/C cooling performance. Refer to «A/C cooling performance, testing»(ref-276291-S09542624172008010300000) .

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)»(ref-276291-S31381018642008010300000) (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»(ref-276291-S21126538962008010300000) .
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)»(ref-276270-S33964324242008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276271-S40733996842008010300000) 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»(ref-276291-S07751104692008010300000) .
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»(ref-276291-S07751104692008010300000) .
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)»(ref-276291-S36678700572008010300000) .

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)»(ref-276270-S33964324242008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU
2. «01 ON BOARD DIAGNOSTIC (OBD)»(ref-276271-S40733996842008010300000) 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)»(ref-276270-S08391981802008010300000) for 1.8 LITER 4-CYL. 5V TURBO FUEL INJECTION & IGNITION, ENGINE CODE(S): AMU
2. «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276271-S29225238592008010300000) 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»(ref-276291-S07751104692008010300000) .
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»(ref-276291-S07751104692008010300000) .

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.

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).

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»(ref-276291-S01974270832008010300000) .

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-)

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»(ref-276291-S12277760792008022600000) 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 cooling performance, testing

Test requirements

1. Radiator and condenser clean (clean if necessary)
2. Ribbed belt OK and correctly tensioned
3. All air ducts, covers and seals OK and properly installed
4. Air flow through dust and pollen filter not obstructed by dirt

1. Heating and A/C unit properly sealed (when fresh air blower is at maximum speed setting, no additional air is drawn in; air delivery is via vents only)
2. Vehicle not standing in direct sunlight
3. Expansion valve insulation properly installed and not damaged.
4. Engine at normal operating temperature

1. All instrument panel vents open
2. Engine running and A/C control head -E87- set to "AUTO" mode
3. Compressor switched on (LED in "ECON" button not lit up)
4. Temperature selection "LO"

1. A/C clutch -N25- engages compressor
2. Coolant fan(s) operate depending on system version noted below

Note. Various A/C refrigerant pressure monitoring/control and coolant fan control versions are possible in conjunction with Coolant Fan Control (FC) Module -J293- Vehicles equipped with A/C pressure switch -F129-: -V7- comes on and runs at speed 1 Vehicles equipped with high pressure switch -G65- and Coolant Fan Control (FC) Module -J293- version "1": -V7- comes on and runs at speed 1 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. Fresh air blower -V2- run at maximum speed Fresh air/recirculated air flap moved to "recirculated air" setting (within 1 minute of starting the engine) Air should come out of the instrument panel vents Both temperature flaps in "cooling" position

Note. If any of the above test requirements is not obtained, check DTC memory. Refer to Diagnostic Trouble Code (DTC) Memory, checking (function 02) and perform output Diagnostic Test Mode (DTM). Refer to Output Diagnostic Test Mode (DTM) (function 03) .

Preparation

1. Check DTC Memory and eliminate any malfunctions that may be displayed. Refer to «Diagnostic Trouble Code (DTC) Memory, checking (function 02)»(ref-276291-S36678700572008010300000) .
2. Perform basic setting (Refer to «Basic Setting (function 04)»(ref-276291-S32423917212008010300000) ) and check control module coding (Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(ref-276291-S07751104692008010300000) ).
3. Close front hood and sunroof.
4. Measure ambient temperature.

1. Close doors and windows.

Testing

1. Switch ignition on.
2. Select "AUTO" mode on A/C control head -E87- and switch temperature setting to "LO"
3. Start engine.

1. A/C clutch engaged, compressor runs.

1. Press button for recirculated air.

1. LED in button lights.

1. Increase engine speed to 2000 RPM (timed period begins).
2. Measure temperature of air delivered by instrument panel vents.

Scheme 11

1. Compare measured values with graph.

A - Temperature of air from center instrument panel vents

B - Measured ambient temperature

C - Permissible temperature range for air from vents

After 5 minutes (depending on ambient temperature) the temperature of air from the center instrument panel vents should settle to within tolerance range -C- on the graph.

If specified values are not obtained. Refer to Identifying malfunctions if specified values are not obtained .

Test requirements

1. Radiator and condenser clean (clean if necessary)
2. Ribbed belt OK and correctly tensioned
3. All air ducts, covers and seals OK and properly installed
4. Air flow through dust and pollen filter not obstructed by dirt

1. Heating and A/C unit properly sealed (when fresh air blower is at maximum speed setting, no additional air is drawn in; air delivery is via vents only)
2. Vehicle not standing in direct sunlight
3. Expansion valve insulation properly installed and not damaged.
4. Engine at normal operating temperature

1. All instrument panel vents open
2. Engine running and A/C control head -E87- set to "AUTO" mode
3. Compressor switched on (LED in "ECON" button not lit up)
4. Temperature selection "LO"

1. A/C clutch -N25- engages compressor
2. Coolant fan(s) operate depending on system version noted below

Note. Various A/C refrigerant pressure monitoring/control and coolant fan control versions are possible in conjunction with Coolant Fan Control (FC) Module -J293- Vehicles equipped with A/C pressure switch -F129-: -V7- comes on and runs at speed 1 Vehicles equipped with high pressure switch -G65- and Coolant Fan Control (FC) Module -J293- version "1": -V7- comes on and runs at speed 1 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. Fresh air blower -V2- run at maximum speed Fresh air/recirculated air flap moved to "recirculated air" setting (within 1 minute of starting the engine) Air should come out of the instrument panel vents Both temperature flaps in "cooling" position

Note. If any of the above test requirements is not obtained, check DTC memory. Refer to Diagnostic Trouble Code (DTC) Memory, checking (function 02) and perform output Diagnostic Test Mode (DTM). Refer to Output Diagnostic Test Mode (DTM) (function 03) .

Preparation

1. Check DTC Memory and eliminate any malfunctions that may be displayed. Refer to «Diagnostic Trouble Code (DTC) Memory, checking (function 02)»(ref-276291-S36678700572008010300000) .
2. Perform basic setting (Refer to «Basic Setting (function 04)»(ref-276291-S32423917212008010300000) ) and check control module coding (Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(ref-276291-S07751104692008010300000) ).
3. Close front hood and sunroof.
4. Measure ambient temperature.

1. Close doors and windows.

Testing

1. Switch ignition on.
2. Select "AUTO" mode on A/C control head -E87- and switch temperature setting to "LO"
3. Start engine.

1. A/C clutch engaged, compressor runs.

1. Press button for recirculated air.

1. LED in button lights.

1. Increase engine speed to 2000 RPM (timed period begins).
2. Measure temperature of air delivered by instrument panel vents.

1. Compare measured values with graph.

A - Temperature of air from center instrument panel vents

B - Measured ambient temperature

C - Permissible temperature range for air from vents

After 5 minutes (depending on ambient temperature) the temperature of air from the center instrument panel vents should settle to within tolerance range -C- on the graph.

If specified values are not obtained. Refer to Identifying malfunctions if specified values are not obtained .

A/C refrigerant system, leak testing

1. Use halogen leak detector Hitec HI400A-TEL or equivalent to check for refrigerant leaks.
2. Refrigerant gas dissipates very quickly. Avoid drafty or windy areas when checking for leaks.
3. Some refrigerant leaks are apparent by refrigerant oil deposits on or near leak location. Confirm by using leak detector.
4. If the refrigerant system is discharged (empty), charge system with approx. 100 g (3.5 oz.) of refrigerant in order to check for leaks.

1. Check refrigerant system for leaks following leak detector manufacturer's instructions.

Scheme 12

1. Check for refrigerant leaks by passing detector probe under suspected leaking components.

Note. Refer to leak detector manufacturer's instructions.

A/C refrigerant system, testing with pressure gauges

Due to the constant temperature/pressure relationship of R-134a, approximate high side system temperature can be determined based on system pressure.

Pressure gauges may have one or more temperature scales in addition to the pressure scale. Since various refrigerants have different temperature/pressure relationships, each gauge is specific for a particular refrigerant.

Measuring pressure and temperature in a "switched-on" refrigerant system

Use the A/C refrigerant high pressure gauge to measure the high side system pressure between the compressor and expansion valve (including condenser) with the A/C switched on.

The temperature display of the high pressure gauge applies only to a portion of the high pressure side. The high pressure gauge displays approximate temperature between the compressor outlet and expansion valve.

Note. The temperature/pressure relationship only holds true when the refrigerant system contains liquid and vapor, but not when it contains only gas. In the gaseous state, the temperature is approx. 10-30 °C (18-54 °F) higher than indicated on the pressure gauge.

Measuring pressure and temperature in a closed container or "switched-off" refrigerant system

Due to the constant temperature/pressure relationship of R-134a, approximate temperature of refrigerant in a closed container or in a switched-off A/C system can be determined based on its pressure.

If the temperature displayed on the gauge is lower than the actual temperature of the refrigerant, the refrigerant container or system is empty (discharged).

Note. The temperature/pressure relationship only holds true when the refrigerant system contains liquid and vapor, but not when it contains only gas. In the gaseous state, the temperature is approx. 10-30 °C (18-54 °F) higher than indicated on the pressure gauge.

Troubleshooting tables

Note. If system performance does not meet specifications after evacuating and recharging system, flush system with compressed air and nitrogen.

Note. If system performance does not meet specifications after flushing with compressed air and nitrogen, evacuating and recharging system, replace expansion valve.

Note. Always replace receiver drier when refrigerant system has been left discharged with open components.

Note. If system performance does not meet specifications after repeating test, re-install original expansion valve, flush system with compressed air and nitrogen and replace compressor.

Note. If system performance does not meet specifications after repeating test, re-install original expansion valve, flush system with compressed air and nitrogen and replace compressor. In cases with "low pressure too low", and the refrigerant fill quantity is found to be OK, check for evaporator icing.

Note. In the above cases, a malfunctioning compressor may have been replaced without having compensated for the amount of refrigerant remaining in the system (replacement compressor was not drained accordingly). Refer to A/C refrigerant system, replacing components .

A/C refrigerant system, symptom based troubleshooting

Test requirements

1. Check DTC memory with VAG 1551 Scan Tool (ST) for any electrical, vacuum or air distribution malfunctions. Refer to «VAG 1551 Scan Tool (ST), VAS 5051 Vehicle Diagnostic Testing and Information System, connecting and selecting functions»(ref-276291-S07751104692008010300000) , correct/repair as necessary before proceeding.

1. There are no shut off requirements for the compressor. Refer to read measuring value block (scan tool function 08), display group 001, display field 1

Note. If DTCs are present for either the A/C pressure switch -F129- or high pressure sensor -G65- and sufficient refrigerant is in the system, carry out electrical testing of these components. Triggering and function of air flow flap and fresh air/recirculated air flap OK All air ducts, seals and covers are OK

If one of the following conditions exists, follow recommended service

A/C does not cool (cooling has stopped completely)

1. Check refrigerant system pressures. Refer to «A/C refrigerant system pressures, checking»(ref-276291-S01259746732008010300000) .

Insufficient cooling during all driving or engine speed (RPM)

1. Check refrigerant system pressures. Refer to «A/C refrigerant system pressures, checking»(ref-276291-S01259746732008010300000) .

1. Pressure switch -F129- disengages A/C clutch -N25
2. Coolant Fan Control (FC) Module -J293- disengages A/C clutch -N25- due to signal from high pressure sensor -G65
3. There is no outside air flow or air flow is severely restricted (evaporator iced up)

A/C compressor noisy

1. Check for loose A/C compressor and compressor bracket mounting bolts. Tighten as necessary.

1. Check routing of A/C refrigerant hoses and lines; hoses and lines must not contact other components and must be installed without binding; reposition or realign as necessary.

A/C compressor noisy immediately after switching A/C ON and/or when driving around corners or braking "refrigerant shock"-refrigerant system overcharged

1. Discharge refrigerant system, evacuate and recharge.

Note. Above condition may also be caused by excessive refrigerant (PAG) oil in system.

With an otherwise properly operating A/C system, water sprays out of instrument panel vents

1. Check evaporator housing drain hose for proper routing (should not be kinked).
2. Check evaporator housing drain valve.

Note. Check evaporator drain plugs for correct installation (should not be pinched or bent). Check drain valves. They must not be plugged with wax, dirt or undercoating (clean if necessary). Valve flaps must close properly. Check air plenum cover (must be properly installed and not damaged).