With Manufacturer's Scan Tool
Compressor Shut-off, Checking
The A/C control head signals the Diesel Direct Fuel Injection Engine Control Module -J248- that the A/C compressor will be switch on, via the A/C compressor signal.
Through another wiring connection, the engine control has the possibility of switching off the air conditioner compressor for various operating conditions:
- Hard acceleration from low speed
- Emergency program (emergency running operation)
- Coolant temperatures above + 120 degree C (248 degree F)
- After every engine start for approx. 6 seconds.
Test sequence
- Connect Scan Tool VAG 1551 (VAG 1552) and select engine electronics control unit with the "Address word" 01. When doing this the engine must be running at idling speed. (Connecting Scan Tool and selecting engine electronics control unit. [1][2][3]Connecting VAG 1551 Scan Tool)
Indicated on display:
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -3- for the function "Output Diagnostic Test Mode".
Indicated on display:
Rapid data transfer Q
03 Final control diagnosis
- Confirm input with -Q- button.
Indicated on display:
Final control diagnosis ->
Commencement of injection valve -N108
- Press the -> button.
Indicated on display:
Final control diagnosis ->
Exhaust gas recirculation valve -N18
- Press the -> button.
Indicated on display:
Final control diagnosis ->
Conditioner compressor interruption
A/C compressor switch-off is checked.
A/C compressor must stop within 5 seconds (visual check) then start approx. every 5 seconds and then stop.
If the A/C compressor is not switched off:
- Proceed with function 3: Output DTM, until complete.
- Press buttons -0- and -6- for the function "End output" and confirm entry with the -Q- button.
- Switch off ignition.
- Remove wiper arms and plenum cover:
- Connect test box VAG 1598/31 to control unit wiring harness.
- Check wiring between test box socket 29 and the A/C system for open circuit using wiring diagram. Wire resistance: Max. 1.5 Ohm
- Check DTC memory and, if necessary, repair any malfunctions and then erase. With Manufacturer's Scan Tool
- Read readiness code. If the DTC memory has been erased or the Diesel Direct Fuel Injection Engine Control Module - J248- was disconnected from permanent battery positive (B+), the readiness code must be generated again.
Monitors, Trips, Drive Cycles and Readiness Codes
Monitors, Trips, Drive Cycles and Readiness Codes