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Home >> Volkswagen >> 2018 >> e-Golf SE >> Repair and Diagnosis >> External Pages >> Different car >> Section 1492 (General, Technical Data (Refrigerant R134A Servicing)) >> 00 General, Technical Data >> Pressures, Checking >> Checking With Expansion Valve, Receiver/Dryer And A/C Compressor Regulator Valve -N280-, Externally Regulated A/C Compressor >> Specified Values
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Specified Values

WARNING: This page is about a different car, the 2014 Volkswagen Touareg, 2013 Volkswagen Touareg, 2012 Volkswagen Touareg, and 2011 Volkswagen Touareg. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

Connect the A/C Service Station. Refer to A/C SERVICE STATION, CONNECTING .

Observe test requirements. Refer to PRESSURES, CHECKING .

-- Bring engine speed up to 2000 RPM.

-- Monitor the pressure gauge on the A/C Service Station.

NOTE:

Switching pressures for actuation of A/C Compressor Regulator Valve -N280- and Coolant Fan -V7- are vehicle-specific.

The pressures should be measured at the service connections. The location of these connections is vehicle-specific. Refer to the appropriate service information. .

High-Pressure Side: 

Increasing from initial pressure (when connecting pressure gauges) to 20 bar (290 psi).

Low-Pressure Side: 

Decreasing from initial pressure (when connecting pressure gauges) to the value in the graph.

GWWA87-0377Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

A  - Low pressure (measured at service connection) in bar absolute

B  - Control current for A/C Compressor Regulator Valve -N280-.

C  - Permissible tolerance range

NOTE:

Under unfavorable conditions (very high ambient temperatures, high humidity), pressure on high-pressure side may increase to max. 29 bar (421 psi).

The control current -B- is shown in the measured value block.

The high pressure measured from the High Pressure Sensor -G65- is not shown in the measured value block. Refer to the appropriate service information .

Low pressure settles as a function of control current for A/C Compressor Regulator Valve -N280- within compressor output range in tolerance range.

Under unfavorable conditions (very high ambient temperatures, high humidity), compressor output may not always be sufficient to attain the specified value.

The specified operating current for the regulator valve must be greater than 0.3 A in order to ensure reliable valve activation.

In the setting "maximum cooling output" control current is regulated to approximately 0.65 A up to 0.8 A (vehicle specific, displayed in measured value block). Refer to the appropriate service information. .

At absolute pressure, 0 bar corresponds to absolute vacuum. Normal ambient pressure corresponds to 1 bar absolute pressure. 0 pressure corresponds to an absolute pressure of one bar on most pressure gauges (indicated by -1 bar (14.5 psi) below 0).

Possible Deviation from Specification Possible Cause of Fault Corrective Action
  • High pressure remains constant or increases only slightly (above pressure with engine stopped).
  • Low pressure quickly drops to value in graph or below.
  • Required cooling output is not attained
  • Activation of A/C Compressor Regulator Valve -N280- is faulty.
  • Not enough refrigerant in refrigerant circuit
 -- Check activation of A/C Compressor Regulator Valve -N280-.-- Localize the leak with leak detector and eliminate-- Charge the refrigerant circuit.
  • High pressure normal.
  • Low pressure in line with value in graph.
  • Required cooling output is not attained
    
  • High pressure normal.
  • Low pressure too low (see graph).
  • Required cooling output is not attained
  • Not enough refrigerant in refrigerant circuit
 -- Extract refrigerant from the refrigerant circuit
  • If quantity of refrigerant extracted is substantially less than specified capacity.
-- Localize leak with leak detector and eliminate.-- Charge the refrigerant circuit.-- Repeat the test.
  • If quantity of refrigerant extracted roughly corresponds to specified capacity:
 
  • Expansion valve faulty
 -- Replace expansion valve-- Charge the refrigerant circuit.-- Repeat the test.
NOTE:

If no malfunction is found with this complaint, flush (clean) refrigerant circuit with refrigerant R134a. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT . If that is not possible in this workshop, flush the refrigerant circuit with compressed air and remove moisture with nitrogen. Refer to REFRIGERANT CIRCUIT, CLEANING WITH COMPRESSED AIR AND NITROGEN .

Check measured values from Evaporator Vent Temperature Sensor -G263- or Evaporator Temperature Sensor -G308- and activation of A/C Compressor Regulator Valve -N280-. If the measured value of the Evaporator Vent Temperature Sensor -G263- or Evaporator Temperature Sensor -G308- is not OK, the evaporator can ice up or the cooling output will not be reached.

If the function of the air conditioning system is not OK when the test is repeated after replacing expansion valve, re-install old expansion valve and flush refrigerant circuit with compressed air and nitrogen. Then replace A/C compressor and receiver/dryer.

With this malfunction, evaporator may ice up although quantity of refrigerant in circuit is OK.

If expansion valve is malfunctioning (permanently closed or does not open sufficiently), A/C Compressor Regulator Valve -N280- is actuated to maximum output and low pressure drops to value in graph or below (compressor draws off refrigerant from low-pressure side). Because refrigerant cannot flow through the expansion valve, the correct cooling output cannot be reached. The high pressure may not increase or may only increase slightly.

Possible Deviation from Specification Possible Cause of Fault Corrective Action
  • High pressure only increases slightly above pressure with engine stopped.
  • Low pressure drops only slightly.
  • Required cooling output is not attained
  • Activation of A/C Compressor Regulator Valve -N280- is faulty.
 -- Check activation of A/C Compressor Regulator Valve -N280-.
 
  • A/C compressor faulty.
 -- Extract refrigerant circuit.-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Replace A/C compressor. -- Charge the refrigerant circuit.
  • High pressure increases above specification.
  • Low pressure quickly drops to value in graph or below.
  • Required cooling output is not attained
  • Activation of A/C Compressor Regulator Valve -N280- is faulty.
 -- Check activation of A/C Compressor Regulator Valve -N280-.
 
  • Constriction or obstruction in refrigerant circuit
 -- Run hand over refrigerant circuit to check for differences in temperature
  • If difference in temperature is found at one component:
-- Replace the hose or pipe if kinked or constricted.-- In the event of an obstruction, flush refrigerant circuit with compressed air and nitrogen -- Charge the refrigerant circuit.-- Repeat the test.
  • If no malfunction can be found:
-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Charge the refrigerant circuit.-- Repeat test if function is not OK.
 
  • Expansion valve faulty
 -- Extract refrigerant circuit.-- Replace expansion valve and receiver/dryer-- Charge the refrigerant circuit.
NOTE:

With this malfunction, evaporator may ice up although quantity of refrigerant in circuit is OK.

If expansion valve is malfunctioning (permanently closed or does not open sufficiently), A/C Compressor Regulator Valve -N280- is actuated to maximum output and low pressure drops to value in graph or below (compressor draws off refrigerant from low-pressure side). Because refrigerant cannot flow through the expansion valve, the correct cooling output cannot be reached. The high pressure may not increase or may only increase slightly.

Possible Deviation from Specification Possible Cause of Fault Corrective Action
  • High and low pressure normal at first, after some time high pressure increases above specification.
  • after some time, low pressure decreases to graph value or lower.
  • Required cooling output is no longer attained.
  • Activation of A/C Compressor Regulator Valve -N280- is faulty.
 -- Check activation of A/C Compressor Regulator Valve -N280-.
  • High pressure and lower pressure normal first, after a long period of driving, the low pressure falls below the specified value (evaporator iced up).
  • Moisture in refrigerant circuit
 -- Extract refrigerant circuit.-- Flush refrigerant circuit with compressed air and nitrogen.-- Replace receiver/dryer with dryer.-- Evacuate refrigerant circuit for at least 3 hours.-- Charge the refrigerant circuit.-- Repeat test, if function is not OK.-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Charge the refrigerant circuit.-- Repeat the test.
NOTE:

If this complaint occurs after a long operating time or only sporadically (the low pressure falls under the specified value and the evaporator ices up), replacing the dryer (installed in the receiver/dryer) is sufficient. The quantity of refrigerant oil should be adjusted. Refrigerant circuit is then to be evacuated for at least 3 hours.

First, it is not necessary to flush the refrigerant circuit with compressed air and nitrogen in case of this complaint because generally only a small amount of moisture is in the system and this can be removed by a long evacuation.

With this malfunction, evaporator may ice up although quantity of refrigerant in circuit is OK.

Possible Deviation from Specification Possible Cause of Fault Corrective Action
  • High pressure normal, low pressure too low (see graph), the necessary cooling output is not reached.
  • Activation of A/C Compressor Regulator Valve -N280- is faulty.
 -- Check activation of A/C Compressor Regulator Valve -N280-.
 
  • Expansion valve faulty
 -- Extract refrigerant circuit.-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Replace expansion valve and receiver/dryer-- Charge the refrigerant circuit.-- Repeat test if function is not OK.-- Replace the A/C compressor.
 
  • A/C compressor faulty.
 -- Extract refrigerant circuit.-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Replace the A/C compressor.-- Charge the refrigerant circuit.-- Repeat the test.
NOTE:

For the malfunction "high pressure normal, low pressure too low", note the following: faulty, the evaporator can ice up or the cooling output is not reached.

With this malfunction, evaporator may ice up although quantity of refrigerant in circuit is OK.

Check measured values from Evaporator Vent Temperature Sensor -G263- or Evaporator Temperature Sensor -G308- and activation of A/C Compressor Regulator Valve -N280-. If the measured value of the High Pressure Sensor -G65- is faulty, the evaporator can ice up or the cooling output is not reached.

If the problem is with the A/C Compressor Regulator Valve -N280- (regulating valve is not actuated but compressor operates nevertheless), refrigerant circuit does not have to be flushed. With this malfunction, replacing the A/C compressor is sufficient (adjust refrigerant oil quantity in new A/C compressor).

If expansion valve is malfunctioning (permanently closed or does not open sufficiently), A/C Compressor Regulator Valve -N280- is actuated to maximum output and low pressure drops to value in graph or below (compressor draws off refrigerant from low-pressure side). Because refrigerant cannot flow through the expansion valve, the correct cooling output cannot be reached. The high pressure may not increase or may only increase slightly.

Refer to the appropriate service information. .

Possible Deviation from Specification Possible Cause of Fault Corrective Action
  • High pressure normal or too high.
  • Low pressure too high (see graph).
  • A/C compressor noise (particularly after switch-on).
  • Required cooling output is not attained
  • Activation of A/C Compressor Regulator Valve -N280- is faulty.
  • Too much refrigerant in the circuit.
 -- Check activation of A/C Compressor Regulator Valve -N280-.-- Extract refrigerant from the refrigerant circuit
  • If quantity of refrigerant extracted roughly corresponds to specified capacity:
-- Replace the A/C compressor.
  • If quantity of refrigerant extracted is substantially greater than specified capacity:
-- Charge the refrigerant circuit.-- Repeat the test.
 
  • To much refrigerant oil in the circuit.
 -- Discharge the refrigerant circuit.
  • If quantity of refrigerant extracted roughly corresponds to specified capacity:
-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Charge the refrigerant circuit.-- Repeat the test.
 
  • Expansion valve faulty
 -- Discharge the refrigerant circuit.-- Replace expansion valve and receiver/dryer-- Charge the refrigerant circuit.-- Repeat test if function is not OK.-- Replace the A/C compressor.
 
  • A/C compressor faulty.
 -- Discharge the refrigerant circuit.-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Replace the A/C compressor.
  • If quantity of refrigerant extracted is substantially greater than specified capacity:
-- Charge the refrigerant circuit.-- Repeat the test.
NOTE:

If the problem is with the A/C Compressor Regulator Valve -N280- (regulating valve is not actuated but compressor operates nevertheless), refrigerant circuit does not have to be flushed. With this malfunction, replacing the A/C compressor is sufficient (adjust refrigerant oil quantity in new A/C compressor).

Overfilling with refrigerant oil can occur if, for example, the A/C compressor was replaced without adjusting the quantity of refrigerant oil.

If the A/C compressor is not replaced, the refrigerant oil should be drained from the A/C compressor via the block connections. Out of the entire quantity of refrigerant oil, 50 grams should be put in the A/C compressor and the rest in the refrigerant circuit. Refer to the Vehicle-Specific Service Information.

If the expansion valve is faulty (constantly closed or does not open far enough), the A/C Compressor Regulator Valve -N280- is actuated to maximum output and low pressure drops to value in graph or below (the A/C compressor draws off refrigerant from low-pressure side). Because refrigerant cannot flow through the expansion valve, the correct cooling output cannot be reached. The high pressure may not increase or may only increase slightly.

Possible Deviation from Specification Possible Cause of Fault Corrective Action
  • High and low pressure normal.
  • Required cooling output is not attained
  • Activation of A/C Compressor Regulator Valve -N280- is faulty.
  • Too much refrigerant oil in the circuit.
 -- Check activation of A/C Compressor Regulator Valve -N280-.-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .
  • High and low pressure normal.
  • A/C compressor noise (particularly after switch-on).
  • The required cooling performance is obtained
  • Too much refrigerant oil in the circuit.
 -- Discharge the refrigerant circuit.-- Flush (clean) refrigerant circuit. Refer to REFRIGERANT CIRCUIT, FLUSHING WITH R134A REFRIGERANT .-- Charge the refrigerant circuit.-- Repeat the test.
 
  • Expansion valve faulty
 -- Replace expansion valve
NOTE:

Overfilling with refrigerant oil can occur if, for example, the A/C compressor was replaced without adjusting the quantity of refrigerant oil.

If the A/C compressor is not replaced, the refrigerant oil should be drained from the A/C compressor via the block connections. Out of the entire quantity of refrigerant oil, 50 grams should be put in the A/C compressor and the rest in the refrigerant circuit. Refer to the Vehicle-Specific Service Information.

If expansion valve is malfunctioning (permanently open), evaporator temperature is no longer regulated such that only refrigerant in gaseous state exits from the evaporator. Under certain usage conditions, liquid droplets may then be drawn in by the compressor and cause noise (liquid cannot be compressed).

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