24-175
      
A/C system signal, checking
 
      The A/C system signal notifies the Engine 
Control Module (ECM), that the A/C system 
requires a higher idle speed to achieve the 
desired interior temperature (regardless of 
whether heating or cooling is required).  
      The increase in idle speed based on presence of 
the A/C system signal is control module 
dependent and occurs only in vehicles with All 
Wheel Drive (AWD) and manual transmission.  
     
Test sequence  
     
-  Connect VAS5051 tester or VAG1551 scan tool 
and select the control module for engine 
electronics using "address word" 01   Page 01
-
9 . 
     
   Engine must run at idle for this.Rapid data transfer  
HELP
Select function XX
    
When indicated on display:  
-  Press buttons -0- and -8- to select "Read Measuring Value Block" and 
press -Q- button to confirm input. 
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