A/C Cooling Performance, Testing

A/C Cooling Performance, Testing

Test requirements
- Radiator and condenser clean (clean if necessary)
- Ribbed belt OK and correctly tensioned
- All air ducts, covers and seals OK and properly installed
- Air flow through dust and pollen filter not obstructed by dirt
- Heating and A/C unit properly sealed (when fresh air blower is at maximum speed setting, no additional air is drawn in; air delivery is via vents only)
- Vehicle not standing in direct sunlight
- Expansion valve insulation properly installed and not damaged.
- Engine at normal operating temperature
- All instrument panel vents open
- Engine running and A/C control head -E87- set to "AUTO" mode
- Compressor switched on (LED in "ECON" button not lit up)
- Temperature selection "LO"
- A/C clutch -N25- engages compressor
- Coolant fan(s) operate depending on system version noted below

NOTE: Various A/C refrigerant pressure monitoring/control and coolant fan control versions are possible in conjunction with Coolant Fan Control (FC) Module -J293-

- Vehicles equipped with A/C pressure switch -F129-: -V7- comes on and runs at speed 1
- Vehicles equipped with high pressure switch -G65- and Coolant Fan Control (FC) Module -J293- version "1": -V7- comes on and runs at speed 1
- Vehicles equipped with high pressure switch -G65- and Coolant Fan Control (FC) Module -J293- version "2": -V7- comes on and runs at speed 1 after refrigerant system pressure has reached 12 bar.
- Fresh air blower -V2- run at maximum speed
- Fresh air/recirculated air flap moved to "recirculated air" setting (within 1 minute of starting the engine)
- Air should come out of the instrument panel vents
- Both temperature flaps in "cooling" position

NOTE: If any of the above test requirements is not obtained, check DTC memory Check DTC Memory (Function 02) and perform output Diagnostic Test Mode (DTM).

Preparation
- Check DTC Memory and eliminate any malfunctions that may be displayed. Check DTC Memory (Function 02)
- Perform basic setting and check control module coding Control Module, Coding (Function 07).
- Close front hood and sunroof.
- Measure ambient temperature.
- Close doors and windows.

Testing
- Switch ignition on.
- Select "AUTO" mode on A/C control head -E87- and switch temperature setting to "LO"
- Start engine.
- A/C clutch engaged, compressor runs.
- Press button for recirculated air.
- LED in button lights.
- Increase engine speed to 2000 RPM (timed period begins).
- Measure temperature of air delivered by instrument panel vents.







- Compare measured values with graph.

A - Temperature of air from center instrument panel vents
B - Measured ambient temperature
C - Permissible temperature range for air from vents







After 5 minutes (depending on ambient temperature) the temperature of air from the center instrument panel vents should settle to within tolerance range -C- on the graph.

If specified values are not obtained.

Identifying malfunctions if specified values are not obtained







- Continued from (compressor was switched off during cooling performance test)







- Continued from (compressor shut-off condition code 1 on vehicles with A/C pressure switch -F129-)