A/C System Cooling Performance, Testing
A/C System Cooling Performance, Testing
NOTE: Beginning with m.y. 1997, A/C pressure switch -F129- replaces pressure switches - F23-, -F73- and -F118-.
Preparations
- Check DTC memory, determine and rectify any displayed malfunctions.
- Perform basic setting. Basic Setting (Function 04)
- Check A/C control head coding. Scan Tool Connecting and Initial Checks (Function 01)
- Close front hood and sunroof.
- Close doors and windows.
- Measure ambient temperature.
Test requirements
- Radiator and condenser are clean (clean, if necessary).
- Drive belts for compressor and Generator in good condition and properly tensioned
- All air guides, covers and seals are in proper order and correctly installed.
- Air flow through dust and pollen filter is not restricted by dust or debris.
- Evaporator and heating system do not draw in any secondary air when the fresh air blower is operating at maximum speed.
- Vehicle is not parked in open sun.
- Engine is at normal operating temperature.
- All instrument panel air outlets are open.
- With engine running and A/C Control head -E87- set for maximum cooling:
- "Auto" mode. (compressor engages, "ice crystal" compressor symbol in left-hand display on).
- Temperature selection "LO."
- Coolant fan -V7- runs (at least in stage 1).
- Fresh air blower -V2- runs at maximum speed.
- Fresh/recirculating air flap moves into "recirculating air mode" position (within 1 minute after engine is started).
- Air flows from instrument panel air outlets.
- Temperature flap is in "cooling" position.
NOTE:
If any one of the test requirements is not achieved:
- Check DTC memory.
- Perform output Diagnostic Test Mode (DTM).Output Diagnostic Test Mode (DTM) (Function 03)
- Read measuring value block.Read Measuring Value Block Tables
Cooling performance testing
- Start engine.
- Set "Auto" mode and "LO" temperature at A/C control head (compressor engages and runs continuously during test).
- Press button for recirculating air flap ("recirculating air mode" symbol in right hand display comes on).
- Run engine at 2000 rpm (start of time measurement).
- Measure air temperature from center instrument panel air outlet.
Compare temperature measurements with diagram.
A - Measured air temperature from center air outlet
B - Measured ambient temperature
C - Permissible temperature range for air outlet temperature
- Measured air temperature from center outlet must be within tolerance range -C- after 5 minutes (ambient temperature dependant).
NOTE:
- Compressor must run continuously during performance test.
- If compressor disengages or temperature specifications are not achieved.