Moisture In The System - Aston Martin DB7 Workshop Manual

Air Conditioning
System Checking with the Manifold Gauge Set
ffi:S5=27
After making the above checks operate the system
and check the performance. If the Condition is not
rectified.
1. inspect the system for overcharge of refrigerant and
rectify as follows.
A. Discharge the system, until a stream of bubbles
appear in the sight glass and both gauge readings
drop to below normal.
B. Add new refrigerant until the bubbles disappear
and the pressures are normal. Then add 0.25 to 0.5
lb. of additional refrigerant.
2. Operate the system and check the performance.
If the gauge readings are still too high.
3. Depressurise the system.
3. Removeand inspectthecondenserforoilclogging.
Clean and flush the condenser to ensure the free
passage refrigerant or renew the condenser.
4. Renew the receiver-drier.
5. Evacuatethesystem using a vacuum pump Recharge
the system with new refrigerant. Operate the system
and check the performance
Moisture in the System
Complaint.
Cooling notadequateduringthe hot part of theday.
Note: Cooling may be satisfactory during early morning/
late evening but inadequate during the hot part of the day.
BLUE LOW SIDE RED HIGH SIDE
1.
2.
3.
4.
5.
LOW
Condition.
The low side gauge reading normal but may drop
into vacuum during testing.
The high side gauge reading normal but drops
when the low side drops into vacuum. The sight
glass may show tiny bubbles.
The discharge air from the evaporator is cold but
becomes warm when the low side gauge drops into
vacuum.
Diagnosis.
Excessive moisture in the system.
Desiccant agent saturated with moisture which is
released during high temperatures. The moisture
collects and freezes in the expansion valve which
stops the refrigerant flow.
Correction.
Depressurise the system.
Renew the drier bottle.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
8-44
May 1996