AC compressor regulating valve -N280
The electric AC compressor regulating valve
-N280 is pushed into the compressor and is secured by a spring ring.
The Climatronic control unit -J255 activates the
compressor by way of the AC compressor regulating valve -N280. The AC
compressor regulating valve -N280 is activated by the Climatronic control unit
-J255 such that the temperature of the air downstream of the evaporator reaches
the specified value (around 2 to 5°C). In loop control mode the duration of the
activation depends on the required cold output, the selected mode of the
Climatronic control unit -J255 and the vehicle voltage The activation does,
however, last at least long enough for a mean current of 0.3 A to flow. For
maximum compressor output, a maximum permissible current of 0.65 A flows via
the AC compressor regulating valve -N280.
J In measured value block 001 display
zone 1 the current flowing via the AC
compressor regulating valve -N280 is displayed.
J If no pressure signal is detected by the
high-pressure sender -G65, the AC compressor regulating valve -N280 must not be
J Liegt eine Kompressorabschaltbedingung vor,
kann das Regelventil für Kompressor der Klimaanlage -N280 (auch
während der Stellglieddiagnose) nicht angesteuert werden. In measured
value block 002, zone 1, the currently present compressor shut-off conditions
J If multiple compressor shut-off conditions
apply simultaneously, the conditions are either displayed alternatingly or only
the shut-off condition assigned the highest priority by the Climatronic control
unit -J255 is displayed.
J Under certain conditions, residual moisture
in the refrigerant circuit may cause ice to form on the AC compressor
regulating valve -N280 (and on the expansion valve). Such ice formation impairs
compressor control; the evaporator is cooled excessively and ices up. Icing-up
of the evaporator may give rise to various complaints.
A Air conditioner; Rep.Gr. 87; Checking AC
compressor regulating valve -N280
A Current flow diagram