Testing engine speed adaptation when air conditioner cuts in — AUDI
Testing engine speed adaptation when air conditioner cuts in on Audi: factory workshop procedure for engines AEB, AEH, AJL, AKL.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📐 46 workshop diagrams for AEB
Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.
📋 Procedure
AJL
Note:
The air conditioner sends a positive signal to contact 10 on the engine control unit.
This positive signal is only sent when a high air conditioner output is required "A/C-High"
When the air conditioner is switched on a positive signal is sent to contact 10 on the engine control unit.
The signal causes the engine control unit to maintain a constant idling speed despite the varying power requirement of the air conditioner.
Test conditions
Air conditioning functioning properly.
No faults recorded in air conditioner fault memory
Interior temperature of more than +15 °C
Connect fault reader V.A.G 1551 => Page
01-3
.
Start the engine (operating temperature).
Switch off rear window heating.
Select the function "Reading measured value block" (function 08) and Display Group 20.
Read measurement block 20
⇒
860 rpm
Neutral
A/C-Low
Compr. OFF
Display readout:
Display zone 1: Idling speed
Display zone 3: Signal from air conditioner
Display zone 4: Signal from air conditioner compressor
Switch on the air conditioner by pressing the "Auto" key. The compressor must run.
Specification for display zone 4: Compr. ON"
Set air conditioning system to maximum cooling or cod output
Specification for display zone 3: A/C - high
Apart from a brief drop in revs, the idling speed should remain constant.
If the idling speed does not remain constant, check whether the engine control unit is receiving the signal from the air conditioner.
Specification for display zone 3: A/C - high
Specification for display zone 4: Compr. ON"
If the specified value is not achieved:
Switch off ignition.
Connect test box V.A.G 1598/22 to wiring harness for engine control unit =>Page
24-7
Test for an open circuit and short to earth or positive in wiring from the contact 10 on engine control unit to the air conditioner.
=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations
If there are no faults in the wiring, check the operation of air conditioner.
=> Air conditioner; Repair Group 01; Self-diagnosis for air conditioner
Air conditioner
Self-diagnosis for air conditioner
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.