Range Rover. Manual — part 292
AIR CONDITIONING
3
FAULT DIAGNOSIS
Symptom - Blower Motor vibration
POSSIBLE CAUSE
REMEDY
1. Blower motor/fan out of
alignment.
1. Check for visual damage.
2. Blower motor/s out of balance.
2. Balance or renew motor/fan assembly.
3. Excessive wear of motor
bearings.
3. Renew motor/fan assembly.
4. Blower motor not mounted
securely.
4. Secure as necessary.
Symptom - Air conditioning system inoperative
POSSIBLE CAUSE
REMEDY
1. Blown air conditioning system
fuse.
1. Check and renew fuses 8 or 17.
2. Switch control panel/ ECU
faulty.
2. Check and renew fuse 8 or fit new switch control panel.
82
AIR CONDITIONING
NEW RANGE ROVER
4
FAULT DIAGNOSIS
REFRIGERANT SYSTEM FAULTS
For any refrigeration system to function efficiently all
components must be in good working order. The
system cooling cycle and the relationship between air
discharge temperature and ambient temperature and
the pressures at the compressor can help in
determining the correct operation of the system. The
length of any cooling cycle is determined by such
factors as ambient temperature and humidity,
thermostat setting, compressor speed and air leakage
into the cooled area, etc. With these factors constant,
any sudden increase in the length of the cooling cycle
would be indicative of abnormal operation of the air
conditioning system.
The low and high side pressures at the compressor
will vary with changing ambient temperature, humidity,
in-car temperature and altitude.
Where the efficiency of the refrigerant system is
suspect, carry out a system performance test.
See
Adjustment. The following components should be
checked before operating the system:
•
Drive belt tension.
•
Compressor clutch operation.
•
Blower motor operation.
•
Condenser unit fins. Build up of dirt will cause
poor cooling and higher operating temperatures.
•
Air filter elements. A blocked filter will restrict
cooling of the evaporator and it is, therefore,
important to renew both filters at the
recommended service schedule.
The following conditions should be checked after
operating the system for several minutes:
•
All high pressure lines should be hot to the
touch.
•
All low pressure lines should be cool to the
touch.
•
Inlet and outlet temperatures at the receiver/drier
should be at the same temperature (warm). Any
noticeable temperature difference would indicate
a blocked receiver/drier.
•
Heavy frost on the expansion valve inlet would
indicate a defective valve or moisture in the
system.
AIR CONDITIONING
5
FAULT DIAGNOSIS
Symptom - High Head Pressure
POSSIBLE CAUSE
REMEDY
1. Overcharge of refrigerant.
1. Discharge, evacuate and recharge system.
2. Air in system.
2. Discharge system, fit new receiver/drier, evacuate and recharge
system.
3. Condenser air passage
blocked with dirt etc.
3. Clean condenser of debris.
4. Condenser fan motor/s
defective.
4. Renew motor/s.
5. Loose compressor drive belt.
5. Check drive belt tensioner or renew drive belt.
6. Seized compressor.
6. Renew compressor.
Symptom - Low Head Pressure
POSSIBLE CAUSE
REMEDY
1. Undercharge of refrigerant.
1. Evacuate and recharge system.
2. Leaking compressor valves.
2. Renew compressor.
3. Defective compressor.
3. Renew compressor.
Symptoms - High Suction Pressure
POSSIBLE CAUSE
REMEDY
1. Loose drive belt.
1. Check drive belt tensioner or renew drive belt.
2. Refrigerant flooding through
evaporator into suction line;
evident by ice on suction line.
2. Renew expansion valve.
3. Expansion valve stuck open.
3. Renew expansion valve.
4. Leaking compressor valves.
4. Renew compressor.
5. Receiver/drier blocked; evident
by temperature difference
between input and output lines.
5. Fit new receiver/drier, evacuate and recharge system.
82
AIR CONDITIONING
NEW RANGE ROVER
6
FAULT DIAGNOSIS
Symptoms - Low Suction Pressure
POSSIBLE CAUSE
REMEDY
1. Expansion valve sticking or
closed.
1. Clean or if renew if necessary.
2. Moisture freezing in expansion
valve orifice. Valve outlet tube
will frost while inlet tube will
have little or no frost.
2. Fit new receiver/drier, evacuate and recharge system.
3. Debris restricting external air
intake grille.
3. Clean air intake grille.
4. Blocked air inlet housing filters.
4. Renew air filters.
5. Defective blower motor/s,
blown fuse/s or loose electrical
connections.
5. Check and renew fuses 42 or 43, tighten all relevant wiring
connections or renew blower motor/s.
Symptom - Noisy Expansion Valve (Steady hissing)
POSSIBLE CAUSE
REMEDY
1. Low refrigerant charge.
1. Test system for leaks; renew components as required.
Symptom - Insufficient Cooling
POSSIBLE CAUSE
REMEDY
1. Expansion valve not operating
efficiently.
1. Renew expansion valve.
2. Low refrigerant charge.
2. Test system for leaks. Evacuate system and renew components as
required. Recharge system.
3. Compressor not pumping.
3. Renew compressor.
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