Measuring Value Blocks (Function 08)
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
- Start engine.
- Set A/C Control Head -E87- to AUTO mode (compressor is switched on).
- Allow fresh-air blower to run at high speed for approx. 1 minute (to allow positioning motors to settle into their final positions).
- Connect VAG 1551 Scan Tool (ST).
- Press buttons -0- and -8- to insert "AC/Heating Electronics" address word 08 and advance program until "Select function XX" appears on display.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08.
Indicated on display
Rapid data transfer Q
08 - Read Measuring Value Block
- Press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block
Input display group number XXX
- Input display group number (overview).
- Press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block X ->
1 2 3 4
To select another display group:
- Press -C- button.
Indicated on display
Read Measuring Value Block
Input display group number XXX
- 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:
- Press -> button.
Indicated on display
Rapid data transfer HELP
Select function XX
Overview of display group numbers which can be selected
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.
- 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.
- 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.
Notes on display field 2:
- When A/C clutch -N25- is switched on the output is closed (voltage greater than 5 V).
- 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, display group 001, display field 1 and appropriate wiring diagram.
Notes on display field 3:
- 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-.
- When A/C pressure switch -F129- is open (high/low pressure switch between terminals 1 and 2) the compressor is switched off display group 001, display field 1.
- 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:
- On Audi TT Coup, display should always read "0".
- 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").
- 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)
NOTE:
- Display group "011" is only available on -E87- with part number suffix "A." and onwards.
- Only compressor cut-out conditions valid for more than 20 seconds are stored.