Road test
Worksheet 69: Check electric window operation and reset position memory
Procedure
Check operation (note that this is a generic procedure, refer to specific information at all times).
Ensure that the battery is charged and then switch on the ignition.
Operate each window from the driver’s switch pack. Check, in each case, for one touch operation as well as limited movement.
Operate each window from the appropriate passenger’s switch.
Move the driver’s safety switch to the ‘isolate rear’ position and then check that the rear windows are locked.
Check the manual, and if a bounce back or back off facility is included, check this by putting a magazine or similar in position so that the window will ‘bounce back’ when it is trapped.
If a ‘global closing’ facility is included, check the operation by opening one or more windows and then locking the car with the remote key. Some vehicles require the key button to be held for a few seconds to make this facility operate.
Switch off the ignition. Position memory reset (generic procedure for anti-trap systems only; check specific data).
Carry the procedure out on each window in turn.
Press the switch to close the window, hold it until the window is fully closed and then for a further second.
Release the button and then press it to the close position again for a second, three more times.
Open the window fully, press the close switch once and check operation.
The window should close fully in automatic mode but repeat the previous procedure if not.
Note that the anti-trap function is disabled until the position memory has been reset.
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Worksheet 70: Inspect and measure electric screen heaters
Note: most screen heaters work on a timer relay. This prevents unnecessary load on the battery and charging system. Make sure the relay is switched on when testing the system. The procedure here can be applied to front or rear screen heaters. Some systems require the engine to be running. Check manufacturer’s data.
Measure the battery voltage. It should be 12.6V or just over.
Switch on the ignition and the front/rear screen heater switch.
Check that the warning light has illuminated.
Where connections can be accessed, connect a voltmeter across the supply terminals.
It should read within about 0.5V of the battery voltage.
Switch off the system and connect an ammeter in series with the heater. This can be done by connecting in place of the fuse using suitable adaptors.
Measure the current draw. Readings will vary, but figures in the region of 20A or more are to be expected. A low reading would indicate a high resistance in the circuit.
Some cars with hatchbacks have contacts that make when the hatch closes. Double check these for operation and cleanliness.
As a final, simple test, switch on the heater and breathe heavily on the screen! The condensation should disappear quickly.
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Worksheet 71: Check driver information systems Procedure
Switch all lights on in turn and check operation of map segments.
Open all doors in turn and check segments.
Switch ignition on and note self-test for ice warning (if fitted).
Refer to handbook as necessary.
Check all functions of trip computer such as time, date and stop watch.
Set a journey distance into the unit.
Road test and note functions such as average speed, estimated time of arrival, fuel consumption and elapsed time.
Reset all when test is complete and make sure that the correct units (miles/kilometres) are set.
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Worksheet 72: Check stoplight operation and adjust switch
position
Procedure
Remove the two wires from the stoplight switch and bridge them together with a fused jumper wire. The ignition may need to be switched on.
The stoplights should light. If not, trace the circuit for a break starting with the fuse.
Note: part of the circuit is in series and part in parallel. If one light is illuminated, the fault must be in the parallel part of the circuit. If neither light is illuminated, the fault must be in the series part of the circuit.
If the lights work when the switch is bridged, the switch needs replacing or adjusting.
Most switches are positioned above the brake pedal and have a screwed body with adjusting nuts. These switches make contact as the plunger springs out.
Adjust the switch position so that the lug on the brake pedal allows the plunger to move as soon as the pedal is pushed down.
Check that the switch is not too sensitive, such that the lights flash on due to vibration for example.
Secure all wires and adjusting nuts – check operation again.
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Worksheet 73: Inspect and measure output from road speed sensor
Procedure
Inductive sensors:
Disconnect the wires (usually two, if a third is used it will be a screen connection to prevent interference entering).
Measure resistance and compare against specifications (often about 800 ohms but double check).
Support the vehicle wheels off the ground and run the car in gear.
Measure ac voltage output and compare against specifications (often about 5 volts ac but this will vary with speed).
Check output signal on a scope. An ac waveform with a frequency that varies with speed is to be expected.
Hall Effect and other types requiring a power supply:
Do not use an ohmmeter as this can damage some types.
Check output signal on a scope. A waveform with a frequency that varies with speed is to be expected.
Reconnect all components.
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Worksheet 74: Check operation of air conditioning system
Start the engine and run until it is warm (use extraction if indoors).
Check the condenser fan operates.
Check for unusual noises in the AC system. Check operation of electrical controls.
Check operation of automatic and semi-automatic HVAC control systems.
Check that the booster fan runs at all speeds.
Set the temperature control to cold, switch AC on and run the fan at maximum speed.
Set air to recirculate and check that cold air is supplied. Some manufacturers specify a temperature at the ventilation outlets of about 5°C.
Leave the AC switched on and set the temperature control to hot. Reset the fan speed to a medium setting.
Run through all direction settings and check that hot air is supplied. Adjustment of operating cables may be required.
Check that a range of temperatures can be selected.
Make sure all ventilation grills open and allow directional control. Adjustment of operating cables may be required.
Inspect heater ducts, hoses and outlets.
Check heated rear screen operation.
Check heated front screen operation (if fitted).
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Worksheet 75: Draining, evacuating and filling an air
Procedure
Note: Always follow the unit manufacturer’s instructions when evacuating of filling a system. At no times should refrigerant be released into the atmosphere.
Many types of servicing units are available so the instructions here are intended to be generic. Any oil lost must be replaced. It is important to ensure the refrigerant handling equipment manufacturer’s instructions are followed during this task.
Particularly with respect to the correct operation and maintenance of the equipment.
Any oil lost must be replaced. It is important to ensure the refrigerant handling
equipment manufacturer’s instructions are followed during this task. Particularly with respect to the correct operation and maintenance of the equipment. Determine the recommended lubricant type and quantity required for the system. Run the engine and operate the AC system for a few minutes (this distributes existing refrigerant evenly and makes extraction easier). Connect the blue servicing unit hose to the low-pressure connector and the red hose to the high-pressure connector. Open the high- and low-pressure valves on the gauges to read pressures. If no pressure exists, then the system has been leaking. In this case it should not be drained as air would get into the
servicing unit.
Switch the servicing unit to ‘Drain’ mode. Some systems are fully automatic others need to be switched off manually. After draining, wait 10 minutes and check the
pressure. If it has risen, there is still refrigerant in the system. Repeat the process again if necessary. The system can now be opened for work to be carried out. The refrigerant in some servicing units is cleaned and recycled automatically. To completely evacuate the system, switch the servicing unit to its ‘Evacuation’ mode. This process can take about 30 minutes. Air conditioning systems are refilled with gaseous refrigerant through the low-pressure connector or liquid refrigerant through the high-pressure connector. Systems should be evacuated before refilling.
High-pressure filling (the preferred method). Check data for the correct quantity of refrigerant and then open the high pressure valve. Switch the servicing unit to ‘Fill’
mode and let the specified quantity of refrigerant flow in. Switch off the unit, close valves and disconnect the hoses.
Low-pressure filling. Check data for the correct quantity of refrigerant and then open the low-pressure valve. Switch the servicing unit to ‘Fill’ mode and let about half the specified quantity of refrigerant flow in. Operate the AC system briefly to distribute the refrigerant and then continue to fill.
Start the engine and switch on the AC and a high blower speed. This ensures the compressor takes the refrigerant residues from the servicing unit. Switch off the unit, close valves and disconnect the hoses. Inspect condition of discharged oil. On
completion of the task, recycled refrigerant should be stored and labelled having consideration for its toxicity and fire hazard.
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Procedure
Drain the AC system as described in Worksheet 75 ‘Draining, evacuating and filling an air conditioning system’.
Remove plastic trims and the bonnet slam panel as required to gain access.
Drain the cooling system and remove radiator (if necessary).
Undo and remove the inlet and outlet pipes from the condenser. Plug the pipes to prevent contamination.
Remove condenser securing screws and note the positions if different sizes are used.
Withdraw the condenser from the vehicle.
Inspect the condenser for air flow restrictions.
Refitting is a reversal of the removal process, but ensure that dirt does not enter the new condenser or the pipes at any time. Use sealant tape on the pipe connections as instructed by the vehicle manufacturer.
Consult manufacturer’s data for the amount of oil to be added to the system.
Evacuate the AC system as described in Worksheet 75.
Refill the AC system as described in Worksheet 75.
Carry out a full check of the AC system operation.
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Worksheet 77: Remove and refit air conditioning
Procedure
Drain the AC system as described in Worksheet 75 ‘Draining, evacuating and filling an air conditioning system’.
Remove electrical connections to the compressor clutch.
Loosen the mounting and belt adjustment bolts. Remove and inspect the belt. Note that the belt, if in good condition, can be left in place on the engine ready for refitting.
Renew if in any doubt.
Undo and remove the inlet and outlet pipes from the compressor. Plug the pipes to prevent contamination.
Remove the compressor securing bolts and withdraw the compressor from the vehicle.
The quantity of oil in the old compressor should be drained and measured.
Remove, inspect and test the compressor clutch.
Test the compressor clutch control system.
Drain the oil from the new compressor and replace with a quantity equal to that drained from the old compressor.
Refitting is a reversal of the removal process, but ensure that dirt does not enter the new compressor or the pipes at any time. Use sealant tape on the pipe connections as instructed by the vehicle manufacturer.
Adjust the drive belt tension to its recommended settings.
Evacuate the AC system as described in Worksheet 75.
Refill the AC system as described in Worksheet 75.
Carry out a full check of the AC system operation.
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Worksheet 78: Remove and refit air conditioning
Procedure
Drain the AC system as described in Worksheet 75 ‘Draining, evacuating and filling an air conditioning system’.
Remove plastic trims and the bonnet slam panel as required to gain access.
Undo and remove the inlet and outlet pipes from the receiver/drier. Plug the pipes to prevent contamination.
Remove receiver/drier securing screws.
Withdraw the receiver/drier from the vehicle.
Refitting is a reversal of the removal process, but ensure that dirt does not enter the new receiver/drier or the pipes at any time. Use sealant tape on the pipe connections as instructed by the vehicle manufacturer.
Consult manufacturer’s data for the amount of oil to be added to the system.
Evacuate the AC system as described in Worksheet 75.
Refill the AC system as described in Worksheet 75.
Carry out a full check of the AC system operation.