SERVICING STATION, CONNECTING FOR MEASURING AND TESTING
- Work procedure may vary depending on the type of tools selected (the tool-specific operating instructions should therefore be followed).
Note. The work procedure is always to be performed as described in the operating instructions for the A/C service station -ROB 134APF- (or subsequent models).
The charging hoses are to be connected as follows to prevent the entry of air or moisture into the refrigerant circuit
Switch off the ignition.
Connect service station to power supply.
Connect quick-release coupling adapter to charging hoses of service station (hand wheels not screwed in/hand shut-off valve not open).
Switch on service station and evacuate charging hoses (only necessary if there is air in charging hoses).
Switch off service station.
Remove sealing caps from service connections or connections with valve (see vehicle-specific refrigerant circuit).
Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Removal and Installation .
Note. Connect filler hose with quick-release couplings to refrigerant circuit service connections.
| CAUTION | Never open valves on low or high-pressure side with engine running. Otherwise, the compressor or service station could be destroyed by a short circuit between the high and low-pressure sides of the refrigerant circuit if the A/C system is switched on. |
Only tighten the handwheel in the quick-release coupling just enough so the service connection is open. Watch the pressure gauge and do not place too much pressure on the valve.
Start the engine and perform the planned tests and measurements.
Compare values determined to specified measured values. Refer to TEST PREREQUISITES .
Loosen the handwheel to close the quick-release coupling before disconnecting it.
TEST PREREQUISITES
Note. Check cooling performance. The air conditioning system is functioning correctly when the air flowing from the instrument panel vents has a temperature of 7 0 C or lower. Setting on Climatronic "LO". Setting on air conditioning system "AC" on; "max" ; "cold". Connections with valve and service connections for measuring and checking.
- Radiator and condenser are clean (clean if necessary)
- Thermal insulation at expansion valve OK and properly installed. Refer to «[For engine(s) BPY, CCTA, BUB, CBFA] Removal and Installation»(ref-475571-S07865064812012052300000) .
- Ribbed belt is OK and properly tensioned. Ribbed belt for A/C compressor and generator are OK and correctly tensioned. Refer to «[For engine(s) BPY, CCTA, BUB, CBFA] Removal and Installation»(ref-475571-S07865064812012052300000) .
- All air ducts, covers and seals OK and properly installed
- Fault finding on the electrical equipment and vacuum system found no malfunction. Refer to «[For engine(s) BPY, CCTA, BUB, CBFA] Diagnosis and Testing»(ref-475571-S11625215002012052300000) .
- The A/C system OBD cannot find malfunctions with the Vehicle Diagnostic Tester in "Guided Fault Finding". The measured value block does not show any shut-off condition for the A/C compressor (only on vehicles with A/C system OBD).
- Air flow through dust and pollen filter not obstructed by dirt. Refer to «[For engine(s) BPY, CCTA, BUB, CBFA] Removal and Installation»(ref-475552-S02201912942012052300000) .
- The heater and A/C unit does not draw in any secondary air at the highest fresh air blower speed. Evaporator and heater not drawing in secondary air at maximum fresh-air blower speed. Refer to «[For engine(s) BPY, CCTA, BUB, CBFA] Description and Operation»(ref-475571-S12854546272012052300000) .
- The air flaps in the heater and A/C unit reach their end position. Refer to «[For engine(s) BPY, CCTA, BUB, CBFA] Description and Operation»(ref-475571-S12854546272012052300000) .
- Fresh-air intake ducts beneath hood and in passenger compartment as well as corresponding water drain valves OK. Refer to «[For engine(s) BPY, CCTA, BUB, CBFA] Diagnosis and Testing»(ref-475571-S11625215002012052300000) .
- Engine is warm
- Vehicle not exposed to direct sunlight
- Ambient temperature greater than 15°C (60°F).
- All instrument panel vents open
- With engine running and maximum cooling output set on air conditioning system
Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Description and Operation .
Set Maximum Cooling Output
Setting on A/C Display Control Head -E87-.
Preselect "Auto" mode (A/C compressor on).
Set temperature selection "LO" for driver's and passenger's side.
Setting on heater controls
A/C button and Rec- or recirculated air button pressed.
Temperature dial in the "Cold" position.
Rotary fresh-air blower control in "4" position.
- The Coolant Fan -V7- runs (the fans run) (at least in level 1).*
Note. For some versions, fan is switched on only once the pressure in refrigerant circuit has exceeded a specified value.
- The Fresh Air Blower -V2- runs at maximum speed.
- Recirculated/fresh-air door set to "air recirculation mode" (within 1 minute after starting vehicle, air-flow door is closed and recirculated air door opened).*
- Is the coolant shut-off valve closed? *
- Are the valves on the pump valve unit closed and the coolant circulation pump is not pumping?