Heating, Ventilation Air Conditioning (A4 Platform): Overview Volkswagen Jetta IV

General Information

OBD program text/data generated by control modules installed on vehicles from m.y. 2002 may not be recognized by VAG 1551/1552 Scan Tools (ST) with the latest program card. For example: scan tool display shows "text 799" , "01529 /references" or similar.

Only the VAS 5051 Vehicle Diagnostic Testing and Information System is capable of processing all display text/data on these vehicles.

All OBD program functions on vehicles from m.y. 2002 must be performed using the VAS 5051 Vehicle Diagnostic Testing and Information System in operating mode "Guided Fault Finding" or "Vehicle Self-Diagnosis".

Climatronic components, checking and adjusting, refer to Climatronic components, checking and adjusting with VAS 5051

The Climatronic control module receives information from various electrical and electronic sensors. This information is processed by the control module according to specified values and then provides corresponding output signals that control electrical components (actuators).

The Climatronic Control Module J255 is integrated into the A/C Display Control Head E87 and cannot be serviced separately. To enable recognition of component malfunctions or if there is an open circuit, the control module is equipped with Diagnostic Trouble Code (DTC) memory.

Should a malfunction be detected in a monitored sensor or component, it is stored in DTC memory.

When malfunctions which have a permanent adverse effect on the operation of the Climatronic are stored in DTC memory, the E87 display flashes for approx. 15 seconds when the ignition is switched on. If there are DTCs that do not cause the display to flash, the Climatronic control module allows the Climatronic to continue to operate in emergency mode at the settings set on the display.

To determine malfunctions detected by OBD, initiate the On Board Diagnostic program and retrieve stored information using the VAG 1551/1552 Scan Tool (ST) or VAS 5051 Vehicle Diagnostic Testing and Information System.

Malfunction information displayed by the scan tool is listed on DTC tables that contain notes on possible causes and repairs.

Sporadic malfunctions (indicated in the readout by "SP" ) are automatically cancelled if not repeated in the next 50 engine starts.

Note. Some components and functions of the Climatronic are not monitored by OBD (e.g. Interior Temperature Sensor Fan V42 ). If there is a specific complaint and no malfunctions are recognized after checking the Diagnostic Trouble Code (DTC) memory, refer to the information listed below.

Additional information

1. Climatronic - General information, refer to «General information»(ref-255032-S17557186562007052300000)
2. A/C refrigerant system, servicing, refer to «A/C Refrigerant System - Servicing»(ref-255032-S08651744952007052300000)
3. Wiring diagrams, refer to Electrical Wiring Diagrams, Troubleshooting and Component Locations
4. Information covering symptoms/causes and corresponding "Service Fixes", refer to Technical Bulletins.

Scheme 1

Special tools, testers and auxiliary items required

1. VAG 1551 Scan Tool (ST)
2. cable VAG 1551/3B
3. VAS 5051 Vehicle Diagnostic Testing and Information System

Climate control system operation

Climatronic is a fully automatic climate control system. The temperature of the interior air supply, fresh air blower speeds and passenger compartment air distribution are regulated automatically. The system features fully digital electronic circuitry and On Board Diagnostic (OBD) capability.

In addition to fully automatic function, air distribution settings and fresh air blower speeds can be selected manually to suit individual needs.

The Climatronic Control Module J255 is the heart of the system. It receives input information from the A/C Display Control Head E87 and various electronic components (sensors and switches). This information is processed by the control module in accordance with specified values and provides corresponding output signals that control electrical components (actuators).

The system controls interior air temperature and distribution. The system continually samples and compares the selected interior air temperature with the actual air temperature measured by the system. Blower speeds, air temperature and distribution are then adjusted and regulated accordingly.

The A/C Display Control Head E87 contains all controls and relevant displays needed to operate the Climatronic system. The systems functional status (mode selection, temperature and air distribution) is displayed in a LCD readout (additional information. Refer to A/C Display Control Head E87 , functions ).

All automatic or manual function selections are input into the A/C control head via buttons located below the display.

When AUTO mode is selected, fresh air blower speed and air distribution signals are provided by E87. The fresh air blower speed is high when there is a large difference between the selected temperature and the actual interior temperature, and low when the difference is small or the same.

The interior temperature setting, operation modes, approximate outside temperature and blower speed are indicated on the A/C control head display at all times. The defrost, vent and footwell air distribution symbols only appear in the display when air distribution is selected manually (AUTO function override). During manual air distribution, the "AUTO" display remains off until such time the AUTO button is pressed.

The system can be switched off completely by pressing the front passenger "decrease fan speed" button until "OFF" appears in the display.

Climate control system options

1. Automatic temperature and fan speed mode
2. Manual temperature and fan speed mode
3. Manual selection of air recirculation mode
4. Manual selection of air flow to instrument panel vents
5. Manual selection of air flow to footwell vents
6. Manual selection of air flow to windshield defroster

Note. Pressing the button AUTO overrides all manually input settings. In ECON operation, only the compressor is switched off. Heating and A/C operations continue to be controlled electronically. Manually selected settings remain stored in memory when the ignition is switched off. Only the function "Air recirculation" is erased after 20 minutes. Climatronic manual operation Owners Manual. A malfunction is present if all display symbols on A/C Display Control Head E87 flash. In this case check the Diagnostic Trouble Code (DTC) Memory first. Refer to Diagnostic Trouble Code (DTC) memory, checking (function 02) .

A/C refrigerant system controls, component overview

Note. Before carrying out any work on the A/C refrigerant system controls, refer to A/C refrigerant system safety measures. Refer to Safety measures . Except where indicated with an asterisk ( * ) all components illustrated must only be serviced or replaced after discharging refrigerant system. Use Kent Moore ACR 4 or equivalent. O-rings used on R-134a systems may be red, green, violet or black. Always plug open refrigerant line connections to prevent dirt and moisture contamination.

Scheme 2

1 - Bolt

1. 15 Nm (11 ft lb)

2 - O-ring

1. Always replace
2. 10.8 mm; 1.8 mm

3 - Receiver drier

1. Always replace
2. Function.

4 - O-ring

1. Always replace
2. 10.8 mm; 1.8 mm

5 - Refrigerant line

1. From receiver drier to expansion valve

6 - Bolt

1. 15 Nm (11 ft lb)

7 - A/C Pressure Switch F129 * or High Pressure Sensor G65 *

1. 15 Nm (11 ft lb)
2. Tightening torque 8 Nm (71 in. lb)
3. Always replace O-ring (note Part No.).
4. F129 electrical checking
5. F129 functional checks
6. G65 checking
7. F129 and G65 can also be checked using VAS 5051 in mode "Guided Fault Finding".
8. G65 monitored by On Board Diagnostic of Engine Control Module (ECM).

Function

1. F129 switches the coolant fan V7 to next higher speed when pressure increases in refrigerant circuit.
2. F129 switches off A/C clutch whenever excessive refrigerant system pressure is present (e.g.: insufficient air flow over condenser or if system is overcharged).
3. F129 switches off A/C clutch whenever insufficient refrigerant system pressure is present (e.g.: refrigerant has leaked out).
4. G65 supplies refrigerant system pressure signal to coolant fan control module J293 and ECM.

8 - O-Ring

1. Always replace
2. 10.8 mm; 1.8 mm

9 - Schrader valve

10 - Threaded plate

11 - O-ring

1. Always replace
2. 10.8 mm; 1.8 mm

12 - Expansion valve

1. Located in right side of engine compartment
2. Hole for refrigerant lines at bulkhead must be must be sealed against splash water
3. Function
4. Removing and installing

13 - Bolt

1. 8 Nm (71 in. lb)

14 - O-ring

1. Always replace
2. 14 mm; 1.8 mm

15 - Damper

16 - Low pressure service valve

1. Only use Kent Moore ACR 4 or equivalent.
2. Removing
3. R-134a capacity. Refer to «A/C Refrigerant System - Capacities»(ref-255032-S14254137392007052300000)

17 - Refrigerant hose

1. From expansion valve to compressor
2. With damper

18 - High pressure service valve

1. Only use Kent Moore ACR 4 or equivalent.
2. Removing
3. R-134a capacity. Refer to «A/C Refrigerant System - Capacities»(ref-255032-S14254137392007052300000)

19 - O-ring

1. Always replace
2. 10.8 mm; 1.8 mm

20 - Evaporator

1. In heating and A/C unit (in passenger compartment)
2. Removing/assembly, refer to «Heating and A/C unit, assembly»(ref-255032-S31374201632007052300000)

21 - O-ring

1. Always replace
2. 16.7 mm; 1.8 mm

22 - Insulation*

23 - O-ring

1. Always replace
2. 7.6 mm; 1.8 mm

24 - Bolt

1. 8 Nm (71 in. lb)

25 - Refrigerant hose

1. From compressor to condenser

26 - Bolt

1. 15 Nm (11 ft lb)

27 - O-ring

1. Always replace
2. 10.8 mm; 1.8 mm

28 - Condenser

1. Removing and installing. Refer to «Condenser, removing and installing»(ref-255032-S32460274092007052300000) .

29 - Compressor

1. Manufacturer: Sanden, designation: SD7V16
2. Manufacturer: Zexel, designation: DCW-17D
3. With A/C Clutch N25
4. Removing and installing from bracket: Refer to applicable engine chapter. Refer to «A/C Compressor and Bracket»(ref-255032-S05936638942007052300000)

30 - O-ring

1. Always replace
2. 14.3 mm; 2.4 mm

31 - Bolt

1. 20 Nm (15 ft lb)

32 - O-ring

1. Always replace
2. 10.8 mm; 1.8 mm

33 - Pressure relief valve

1. Checking

34 - A/C Clutch N25 *

1. Sanden, servicing: Refer to «A/C Clutch N25 - Sanden, servicing»(ref-255032-S18513581012007052300000) .
2. Zexel, servicing: Refer to «A/C Clutch N25 - Zexel, servicing»(ref-255032-S19300270202007052300000) .

Refrigerant (PAG) oil R-134a, identification

Use only the correct type of refrigerant oil (PAG oil) specified for use with R-134a and compressor type.