Restrictor, Reservoir and A/C Compressor Regulator Valve N280 (With Externally Regulated Compressor)
Pressures, Checking For Vehicles With Restrictor, Reservoir And A/C Compressor Regulator Valve N280 (with Externally Regulated Compressor)
NOTE:
- Connecting service station. Pressures, Checking on Vehicles
- Observe test conditions. Refrigerant Circuit, Checking Pressures (Using Service Station)
- Set engine speed to 2000 rpm.
- Observe pressure gauge of service station.
NOTE:
- Switching pressures for actuation of A/C Compressor Regulator Valve N280 and Coolant Fan V7 are vehicle-specific.
- Pressures must be measured at service connections; component locations of these connections are vehicle-specific Heating, air conditioning or Air conditioning.
Specifications
High-pressure side:
Increasing from initial pressure (on connection of pressure gauges) to 20 bar
Low-pressure side:
Decreasing from initial pressure (on connecting pressure gauges) to value in graph
A. Low pressure (measured at service connection) in bar absolute
B. Control current for A/C Compressor Regulator Valve N280 in amps
C. Permissible tolerance range (applicable to compressor capacity utilization of 10...90%)
NOTE:
- Given high ambient temperature and a low engine speed, compressor may for example no longer be able to adjust pressure on low-pressure side to value given in graph. Compressor is actuated with maximum specified control current, however delivery volume is no longer sufficient at this engine speed to reduce pressure on low-pressure side to value in graph , air conditioner "Guided Fault Finding" function and Heating, air conditioning or Air conditioning.
- Under unfavorable conditions (very high ambient temperatures, high humidity), pressure on high-pressure side may increase to max. 29 bar.
- Control current - B - is displayed in measured value block of A/C Control Head E87 or control head, Climatronic Control Module J255.
- Pressure in refrigerant circuit measured by High Pressure Sensor G65 or A/C Pressure/temperature Sensor G395 is displayed in measured value block of A/C Control Head E87 or control head, Climatronic Control Module J255 and Heating, air conditioning or Air conditioning.
- Low pressure settles as a function of control current for A/C Compressor Regulator Valve N280 within compressor output range in tolerance band.
- Under unfavorable conditions (very high ambient temperatures, high humidity), compressor output may not always be sufficient to attain the specified value.
- If compressor capacity utilization is greater than 90 %, pressure on low-pressure side may be in excess of tolerance range "C" shown in graph (compressor output no longer suffices).
- The specified operating current for the regulator valve must be greater than 0.3 A in order to ensure reliable valve actuation.
- At absolute pressure, 0 bar corresponds to an absolute vacuum. Normal ambient pressure corresponds to 1 bar absolute. On the scales of most pressure gauges, 0 bar corresponds to an absolute pressure of 1 bar (can be seen from -1 bar mark below 0).
- In "maximum cooling output" setting, control current is regulated to approx. 0.65 (vehicle-specific up to 0.85 A) (displayed in measured value block), air conditioner "Guided Fault Finding" function and Heating, air conditioning or Air conditioning.