Testing signals from/to air conditioner: Audi 1.8 (ADR)
Step-by-step testing signals from/to air conditioner for the Audi 1.8 (ADR): factory workshop text. What to remove, in what order, and what to check after.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
🔧 Engine codes this applies to
📐 36 workshop diagrams for ADR
Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.
📋 Procedure
Special tools and workshop equipment required
V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598/22
VAS 5051 with VAS 5051/1 and VAS 5051/2
or
V.A.G 1551withV.A.G 1551/1
Testing air conditioner compressor signal and compressor shut-off
The air conditioner compressor signal informs the engine control unit that the compressor will be switched on in 140 ms.
The engine control unit can send a signal via the same wire to shut off the air conditioner compressor.
The engine control unit will shut off the air conditioner compressor in the following cases:
For approx. 4 seconds during sharp acceleration from a low speed (registered via angle change on throttle valve potentiometer and road speed signal)
At full throttle in 1st gear for approx. 12 seconds
Defective throttle valve control part, engine speed of less than 1500 rpm
For approx. 6 seconds each time engine is started
For approx. 15 seconds during learning process for idling speed stabilisation
Requirements for test:
No faults stored in fault memory
Vehicle at room temperature
(above +15 °C)
Air conditioner okay
Test sequence
Read measured value block 20
⇒
860 rpm
neutral
A/C-Low
Compr.OFF
Read measured value block, Display Group 020, engine at idling speed=>Page
01-59
.
Check display in display zone 4.
Specification: "Compr.OFF"
Switch on air conditioner.
Specification for display zone 4: "Compr. ON"
Floor and release the accelerator quickly (short blip).
Specification for display zone 4: The display should change from "ON" to "OFF" for a few seconds (air conditioner compressor shut-off during acceleration).
If the displays are not as described:
Connect test box V.A.G 1598/22 to wiring harness for engine control unit
=> Page
24-12
.
Test for open circuit and short to positive or earth in the following wiring connections:
Test box / V.A.G 1598/22 / Socket · Magnetic clutch / control unit -J153 / Contact
8 · => Current flow diagrams, / => Electrical fault-finding / => and Fitting locations binder
Rectify any open/short circuit as necessary.
If there are no faults in the wiring, test operation of air conditioner.
=> Heating, Air conditioner; Repair group 87; Air conditioner; Servicing components for air conditioner with manual controls
Heating, Air conditioner
Air conditioner
Servicing components for air conditioner with manual controls
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.