A Large Amount Of Air In The System; Expansion Valve Malfunction - Aston Martin DB7 Workshop Manual

=2? Air Conditioning
System Checking with the Manifold Gauge Set
A Large Amount of Air in the System.
Complaint.
Little or no cooling.
1.
2.
3.
4.
5.
BLUE LOW SIDE
RED HIGH SIDE
Condition.
The low side gauge reading is too high. The high
side gauge reading is too high. An occasional
bubble in the sight glass. The discharge air from the
evaporator is not cool.
Diagnosis.
Air in the system. The refrigerant contaminated by
non-condensables (air and/or moisture).
Correction.
Depressurise the system.
Renew the receiver-drier.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
Expansion Valve Malfunction.
The valve stuck open.
1.
2.
3.
4.
5.
6.
BLUE LOW SIDE
HIGH
Complaint.
Little or no cooling.
Condition.
The low side gauge reading is too high.
The high side gauge reading is normal or slightly
low.
The discharge air from the evaporator is warm. The
suction hose and the evaporator show signs of
heavy sweating.
Diagnosis.
The expansion valve allowing excessive flow of
refrigerant through the evaporator coils causing
flooding of the coils.
Correction.
Depressurise the system.
Renew the expansion valve.
Renew the drier bottle.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
May 1996 8-45