General information
OBD program text/data generated by control modules installed on vehicles from 12.01 production may not be recognized by Scan Tool VAG 1551 or VAG 1552 with the latest program card. For example: scan tool display shows "text 799" , "01529/references" or similar.
Only the Vehicle Diagnostic Testing and Information System VAS 5051 or VAS 5052 is capable of processing all display text/data on these vehicles.
In addition, performing OBD program functions such as control module coding etc., system specifications and operation may have changed on vehicles from 12.01 production. In these cases, information in section for models through 11.01 production is NOT applicable.
OBD program functions on vehicles from 12.01 production must be performed using the Vehicle Diagnostic Testing and Information System VAS 5051 or VAS 5052 in mode "Guided Fault Finding".
The Climatronic Control Module J255 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 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 A/C Control Head E87 display flashes for approximately 15 seconds when the ignition is switched on. If there are DTCs that do not cause the display to flash, the Climatronic Control Module J255 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 Scan Tool VAG 1551 or VAG 1552 or Vehicle Diagnostic Testing and Information System VAS 5051 or VAS 5052 in operating mode "Vehicle Self Diagnosis".
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 system are not monitored by On Board Diagnostic (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
- A/C refrigerant system, servicing --> «A/C Refrigerant System Servicing»(ref-255355-S31794454622007053000000)
- Digital Climate Control - Climatronic --> «Climatronic»(ref-255355-S05302692682007053000000)
- Technical Bulletins covering symptoms/causes and corresponding "Service Fixes" --> Technical Bulletins.
Scheme 1
Special tools, testers and auxiliary items required
- Scan Tool VAG 1551
- Adapter Cable VAG 1551/3B
- Vehicle Diagnostic Testing and Information System VAS 5051
Climatronic is a fully automatic, digital-electronic 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 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 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.
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 the A/C Control Head 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.
A/C compressor - 8-cylinder engine, general information
8-cylinder models are equipped with Denso compressor 7SEU16. This compressor is driven continuously when the engine is running (no A/C clutch present).
Compressor output is regulated by the Climatronic Control Module J255 based on input signals from High Pressure Sensor G65 and control of signal to A/C Compressor Regulator Valve N280.
A/C Compressor Regulator Valve N280 is not activated with empty refrigerant circuit (compressor idles with engine).
An internal oil circuit in the compressor ensures the compressor is not damaged when the refrigerant circuit is empty. This feature depends on a residual amount of refrigerant oil being present in the circuit.
A/C refrigerant system, identification
Note. Before carrying out any work on the A/C refrigerant system, refer to A/C system safety measures WARNINGS! and CAUTIONS! --> A/C Refrigerant System - General
A/C refrigerant systems on Passat models are charged with refrigerant R-134a.
Labels specifying refrigerant type are located on the compressor or radiator support. Before proceeding with refrigerant system servicing or repairs, always confirm refrigerant type used.
Scheme 2
1 - Compressor
2 - Condenser
3 - Restrictor
4 - Evaporator
5 - Accumulator
Note. Arrows indicate direction of refrigerant flow.
A/C refrigerant system, component overview
Note. Before carrying out any work on the A/C refrigerant system, refer to A/C system safety measures WARNINGS! and CAUTIONS! --> A/C Refrigerant System - General
Scheme 3
The compressor is driven via a belt on the engine when the A/C Clutch engages (A/C "ON" ).
Low-pressure refrigerant gas from the evaporator is compressed by the compressor. After compression, the refrigerant gas (now high-pressure) flows to the condenser.
Refrigerant system pressures and A/C outlet temperatures are regulated by cycling the A/C clutch on and off according to the selected temperature.
Note. The compressor contains refrigerant oil that is mixable under all temperatures with the refrigerant. A label on the compressor indicates that compressor is for R-134a systems only.
Scheme 4
On 8-cylinder models with externally regulated Denso compressor 7SEU16, the compressor is driven continuously (no A/C clutch). Compressor output is regulated by the Climatronic Control Module J255 based on input signals from the High Pressure Sensor G65 and Evaporator Vent Temperature Sensor G263. Climatronic Control Module J255 provides an output signal to A/C Compressor Regulator Valve N280 in accordance with the interior temperature setting and refrigerant system pressures/engine load.
Low-pressure refrigerant gas from the evaporator is compressed by the compressor. After compression, the refrigerant gas (now high-pressure) flows to the condenser.
Note. From start of production, several compressor and A/C clutch types (manufacturers) with specific servicing requirements are installed --> A/C Refrigerant System Servicing . The compressor contains refrigerant oil that is mixable under all temperatures with the refrigerant. A label on the compressor indicates that compressor is for R-134a systems only.
Scheme 5
On A/C compressors without A/C Clutch N25 , the A/C Compressor Regulator Valve N280 is integrated with the A/C compressor. Its function is controlled by the Climatronic Control Module J255 based on input signals from the High Pressure Sensor G65 and Evaporator Vent Temperature Sensor G263. Climatronic Control Module J255 provides an output signal to A/C Compressor Regulator Valve N280 in accordance with the interior temperature setting and refrigerant system pressures/engine load. The valve regulates the low pressure (suction) side of the A/C compressor, thus controlling the evaporator temperature.
Scheme 6
The condenser transfers heat from the compressed refrigerant gas to the outside air which causes the refrigerant to change state from a gas to a liquid.
Note. The condenser for the R-134a refrigerant system is identified with a green label.
Scheme 7
The restrictor restricts and controls refrigerant flow to the evaporator thus lowering refrigerant temperature and pressure.
Upstream of the restrictor, the refrigerant is hot and under high pressure. Downstream of the restrictor, the refrigerant is cold and under low pressure.
A strainer located upstream of the restrictor filters out any dirt or particles. Another strainer downstream of the restrictor atomizes the refrigerant before it enters the evaporator.
Note. Insert restrictor so that arrow - A - points to evaporator.
Scheme 8
Liquid refrigerant entering the evaporator absorbs heat from air passing through the evaporator fins and cools the air. As the refrigerant absorbs heat it turns to vapor and then is suctioned by the compressor.
PAG oil, identification
Use only the PAG oil(s) specified below for use with R-134a and compressor type.
| Compressor | Refrigerant oil Part No. |
|---|---|
| Denso 7SB-16C/7SEU16 | G 052 300 A2 |
| Zexel DCW-17D | G 052 154 A2 or G 052 200 A2 |
| CAUTION | Part numbers are for reference only. Always check with for Parts Department for latest parts information. |