01-46
 Output Diagnostic Test Mode (DTM) table
 
VAG1551 scan tool display  
Specified function  
Corrective action  
A/C Clutch N25 
 
 
 
 
 
 
 
  
Notes:  - N25 clicks every 2-seconds
- Output of A/C control head -E87- is switched from 0 V to 
12 V every 2-seconds2) - Test voltage supply for -
N25- (via A/C Clutch 
Relay J44) using wiring 
diagram 
- Repair or replace -N25- 
 page 87
-90
  
- Test circuit and 
connectors between A/C 
control head -E87-, J44 
and -N25- using wiring 
diagram 
- Replace -E87-
 
"A/C compressor on" output to 
Engine Control Module (ECM) 
and -E87- terminal -C12- is 
also actuated at the same 
time1) 
Output of -E87- switched from 0 V to 12 V every 2 
seconds can be confirmed by switching compressor on 
and off using the "ECON" button while reading the 
measured value block of engine control module   
Repair Manual, Fuel Injection and Ignition System, 
Repair Group 01) 
  
1)Test this "A/C compressor on" signal only if complaints exist. ECM uses signal to compensate for engine load when 
compressor engages   Repair Manual, "Fuel Injection & Ignition," Repair Group 24 . ECM is capable of switching off the A/C compressor from this signal. Confirm via function 08, Read measuring value block, 
page  Page 01
-63
 , display group 01 and Fuel Injection and Ignition System Repair Manual, Repair group 01: Read 
measured value block of ECM with engine running and at same time switch compressor on and off. 
Pa
ge 65 of 91 A/C s
ystem, On Board Dia
gnostic 
(OBD
)
11/21/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
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pair&id=AUDI.B5.HA01.01.1