Pressures, Checking
-- Switch off the ignition.
-- Connecting service station, refer to SERVICING STATION, CONNECTING FOR MEASURING AND TESTING .
-- Take pressure gauge readings (two possible results).
| Ambient Temperature (In Degrees Celsius) | Pressure In Refrigerant Circuit In Bar Positive Pressure |
|---|---|
| + 15 °C | 3.9 |
| + 20 °C | 4.7 |
| + 25 °C | 5.6 |
| + 30 °C | 6.7 |
| + 35 °C | 7.8 |
| + 40 °C | 9.1 |
| + 45 °C | 10.5 |
Temperature of refrigerant circuit components should be equal to ambient temperature.
Pressure will deviate from values in table if individual components of refrigerant circuit are warmer or colder.
At absolute pressure, 0 bar corresponds to absolute vacuum. Normal ambient pressure (positive 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 below 0).
On vehicles with High Pressure Sensor -G65- with which the measured pressure is displayed in the measured value block, the measured pressure should correspond to the values in the table.
Refer to [For engine(s) BLV, CCTA, CBFA] Description and Operation .
Pressure in refrigerant circuit lower than indicated in table
Not enough refrigerant in refrigerant circuit.
-- Determine refrigerant circuit leaks. Refer to REFRIGERANT CIRCUIT, FINDING LEAKS WITH ELECTRONIC LEAK DETECTOR VAG 1796 .
-- Check pressure relief valve.
If pressure relief valve has responded:
-- Check coolant fan activation.
-- Check refrigerant lines and hoses for cross-section constrictions caused by inadequate bending radii.
-- Check refrigerant pipes and hoses for external damage.
-- If no malfunction is found, flush refrigerant circuit with compressed air and nitrogen.
Pressure in refrigerant circuit in line with table or higher
-- Start the engine.
-- Set air conditioning system to maximum cooling output.
If the low pressure switch was removed to connect the service station, bridge the electrical connections in the corresponding connector for the pressure measurement.
- A/C compressor is driven by the engine via A/C Clutch -N25-.
- The A/C Compressor Regulator Valve -N280- is activated by the Climatronic Control Module -J255-.
Refer to [For engine(s) BLV, CCTA, CBFA] Description and Operation
If compressor is not driven with engine running or regulating valve is not actuated
-- Determine and eliminate cause for example, by checking air conditioner DTC memory.
-- Observe test conditions.
-- Check the A/C clutch -N25- voltage supply. If it is OK, repair the A/C clutch.
-- Check activation of A/C Compressor Regulator Valve -N280-. Refer to [For engine(s) BLV, CCTA, CBFA] Description and Operation .
- Check on vehicles with restrictor and reservoir (with internally regulated A/C compressor). Refer to CHECKING WITH RESTRICTOR AND RESERVOIR WITH INTERNALLY REGULATED A/C COMPRESSOR .
- Check on vehicles with expansion valve and reservoir (with internally regulated A/C compressor). Refer to CHECKING WITH EXPANSION VALVE AND RESERVOIR WITH INTERNALLY REGULATED A/C COMPRESSOR .
- On vehicles with expansion valve and reservoir (without regulated A/C compressor). Refer to CHECKING WITH EXPANSION VALVE AND RESERVOIR WITHOUT REGULATED A/C COMPRESSOR .
- Checking pressures for vehicles with restrictor, reservoir and A/C Compressor Regulator Valve -N280- (externally regulated A/C compressor). Refer to CHECKING WITH RESTRICTOR, RESERVOIR AND A/C COMPRESSOR REGULATOR VALVE N280 .