Audi Workshop Service and Repair Manuals > A3 Mk1 > Power unit | Motronic injection and ignition system (4-cyl.) | Mixture preparation system, electronic inj.,Gas | Checking additional signals | Checking air conditioner compressor shutoff

Motronic injection and ignition system (4-cyl.)

Checking additional signals

Checking air conditioner compressor shutoff

Notes:

◆ The air conditioner compressor signal provides the engine control unit with the information that the compressor is to be switched on in 140 ms.
◆ The engine control unit can use the same wire to shut off the air conditioner compressor.
◆ The air conditioner compressor is shut off by the engine control unit:

Test requirements

‒ Connect vehicle diagnostic, testing and information system VAS 5051 or fault reader V.A.G 1551 and select engine electronics control unit with "address word" 01 .
Ignition must be on.

→ Indicated on display:

Rapid data transfer HELP

Select function XX

‒ Press keys 0 and 8 for "Read measured value block" function and confirm entry with Q key.

→ Indicated on display:

Read measured value block

Enter display group number XXX

‒ Press keys 0, 5 and 0 for "Display group number 50" and confirm entry with Q key.

→ Indicated on display:

Read measured value block 50 ⇒

1 2 3 4


	Display zones
	1	2	3	4
Display group 50: Signals to engine control unit
Display	xxx rpm	xxx rpm	A/C Low	Compr. OFF
Readout	Engine speed - ACTUAL (actual engine speed)	Engine speed - SPECIFIED (theoretical engine speed)	Air conditioner requirement	Air conditioner compressor status
Operating range			A/C Low A/C High	Compr. OFF Compr. ON
Specification			A/C Low	Compr. OFF Compressor OFF

‒ Switch on air conditioner with "Auto" button. Compressor must run (display zone 4).
‒ Set air conditioner to maximum cooling/ heating (display zone 3).


	Display zones
	1	2	3	4
Display group 50: Signals to engine control unit
Display	xxx rpm	xxx rpm	A/C High	Compr. ON
Readout	Engine speed - ACTUAL (actual engine speed)	Engine speed - SPECIFIED (theoretical engine speed)	Air conditioner requirement	Air conditioner compressor status
Operating range			A/C Low A/C High	Compr. OFF Compr. ON
Specification			A/C High	Compr. ON Compressor ON

‒ Abruptly floor accelerator pedal and release it again (brief burst of throttle).

‒ Specification in display zone 4: Display switches for several seconds from "Compr. ON" to "Compr. OFF" (compressor shut-off on vehicle acceleration)

If display in zone 4 is not as described.

‒ Switch off ignition.
‒ Connect test box V.A.G 1598/31 to engine control unit wiring harness. Actual engine control unit is not to be connected.

Check for short to positive/earth and open circuit in the following wiring.


Test box V.A.G 1598/31, socket	Air conditioner, contact
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