Restriction In The High Pressure Side; Expansion Valve Malfunction - Aston Martin DB7 Workshop Manual

Air Conditioning
System Checking with the Manifold Gauge Set
^^?
Expansion Valve Malfunction
The valve stuck closed.
Restriction in the High Pressure Side.
BLUE LOW SIDE
SED HIGH SIDE
Complaint.
Cooling is not adequate.
Condition.
1. The low gauge reading is too low (0 or a vacuunn).
2. The high side gauge reading is too low.
3. The discharge air from the evaporator only slightly
cool.
4. The expansion valve shows signs of heavy sweating
or frost.
Diagnosis.
The expansion valve restrictingthe refrigerant flow.
Correction.
1. Depressurise the system.
2. Renew the expansion valve.
3. Renew the drier bottle.
4. Evacuate the system using a vacuum pump.
5. Recharge the system with new refrigerant.
6. Operate the system and check the
performance.
1.
2.
3.
4.
1.
2.
3.
4.
5.
BLUE LOW SIDE
Complaint.
Cooling is not adequate.
Condition.
The low side gauge reading is low.
The high side gauge reading builds up to an
excessively high reading.
The discharge air only slightly cool.
The high pressure liquid hose from the drier bottle
to the evaporator is cool to the touch or shows signs
oi heavy sweating or frost.
Diagnosis.
A restriction in the receiver-drier orthe high pressure
liquid hose from the drier bottle. Which results in
the compressor removing refrigerant from the
evaporator faster than it can enter. This results in a
starved evaporator.
Correction.
Depressurise the system.
Renew the drier bottle and/or the high
pressure liquid hoses or other defective parts.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
8-46
May 1996