Refrigerant Excessively Low; Air In The System - Aston Martin DB7 Workshop Manual

Air Conditioning
System Checking with the Manifold Gauge Set
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Refrigerant Excessively Low.
Complaint.
Cooling is not adequate.
Air In The System.
Complaint.
Cooling is not adequate.
BLU£ LOW SIDE
SlUE LOW SIDE
M D HIGH SIDE
5.
6.
7.
Condition.
1. The low side gauge is reading very low.
2. The high side gauge reading very low.
3. No bubbles or liquid evident in the sight glass.
4. The discharge air from the evaporator is warm.
Diagnosis.
System refrigerant excessively low. Serious leak
indicated.
Correction.
1. Test the system for leaks.
Note: Partially recharge the system before testing the
system for leaks to ensure that leak detection is obtained.
Depressurise the system.
Repair the leaks, and if necessary renew hoses or
units.
Check the compressor oil level. The system may
have lost oil due to leakage.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
performance.
2.
3.
5.
6.
7.
8-42
Condition.
The low side gauge reading is constant and does not
drop. The pressure should drop until the compressor
cycles (thermostat control)
The high side gauge reading is slightly high (or
slightly lower especially if a large fan is used to
substitute ram air).
The sight glass is free of bubbles or only shows an
occasional bubble.
Thedischarge air from theevaporator is only slightly
cool.
Diagnosis.
Non condensables present in the system. Air or
moisturepresent instead of afullrefrigerantcharge.
Correction.
Test the system for leaks. Test the compressor seal
area very carefully.
Depressurise the system. Repair the leaks, and if
necessary renew hoses or units.
Renew the drier bottle, probably water saturated .
Check the compressor oil level.
Evacuate the system using a vacuum pump.
Recharge the system with new refrigerant.
Operate the system and check the performance.
May 1996