belt AUDI A4 1999 B5 / 1.G AC System On Board Diagnostic Workshop Manual

01-34

DTC 01270 continued
VAG1551 scan
tool display Possible cause
Corrective action
01270 4121
A/C Clutch N251)

Speed difference
too great /SP3)












Continued on
next page. - Ribbed belt loose, slipping



- A/C control head -E87- not coded correctly
- Loose terminal or contact resistance in circuit between
-N25- and A/C clutch relay -J44- or in wiring/connections
between -G111-2)4) and -E87-
- N25 slipping
- Incorrect crankshaft vibration damper (diameter)
- Malfunction in refrigerant circuit (compressor not
operating freely). - Check belt tension Repair Manual,
Engine Mechanical, Repair Group 13
Compare speeds of engine and compressor
using function 08 (Read measuring value
block) page 01
-63

- Code A/C control head -E87- according to
compressor type installed4) "Zexel" or
"Nippondenso" page 01
-57

- Diagnose and repair circuit using wiring
diagram and perform electrical tests
page 01
-115

- -G111-, -J44- electrical test page 01
-
115

- Repair or replace -N25- page 87
-85
- Check for proper vibration damper part
number
- Check compressor for free operation and
replace if necessary page 87
-38

1/2) Continued from page 01
-33

3) If speed difference is 30 % to 60 %, A/C Clutch is switched on again by -E87- for not more than 9 times during a driving
period (ignition off). If speed difference is greater than 60 %, A/C Clutch remains off until engine is started again.
Pa
ge 44 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
yp
e=re
pair&id=AUDI.B5.HA01.01.1

01-35

DTC 01270 continued
VAG1551 scan tool
display Possible cause
Corrective action
01270 4121
A/C Clutch N251)

Mechanical
malfunction /SP2) - Belt and coupling pulley of -N25- are stuck together
- Short circuit to positive in wiring/connections between -
N25- and for A/C Clutch relay -J44-
- -J44- malfunction
- Short circuit to ground in wiring/connections between -E87-
and -J44- - Repair or replace -N25-
page 87
-85


- Diagnose and repair short
circuit using
wiring diagram

- Replace -J44-
- Diagnose and repair short
circuit using
wiring diagram.
01271 4122
Temperature Regulator
Flap Motor V68

Blocks or de-energized
/SP - Short circuit, open circuit or incorrect terminal assignment
(wires interchanged) of connectors between -V68- and -E87-
- Temperature flap sticking
- -V68- malfunction- Diagnose and repair short
circuit, open
circuit or confirm terminal
assignment using wiring
diagram
- Check for free operation of
temperature flap
- Test -V68- using function 03
(Output DTM)
page 01
-42

Pa
ge 46 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
yp
e=re
pair&id=AUDI.B5.HA01.01.1