No Cooling; Insufficient Cooing; System Trouble Shooting 8-1 - Aston Martin DB7 Workshop Manual

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Air Conditioning
System Trouble Shooting
System Trouble Shooting
There are five basic symptoms associated with air conditioning fault diagnosis. It is very important to identify the area of
concern before starting a rectification procedure. Spend time with your customer on problem identification, and use the
following trouble shooting guide.
The following conditions are not in order of priority.
N o Cooling
1. Is the electrical circuit to the compressor clutch functional?
2. Is the electrical circuit to the blower motor(s) functional?
3. Slack or broken compressor drive belt.
4. Compressor partially or completely seized.
5. Compressor shaft seal leak (see 9).
6. Compressor valve or piston damag^ (may be indicated by small variation between HIGH & LOW side pressures
relative to engine speed).
7. Broken refrigerant pipe (causing total loss of refrigerant).
8. Leak in system (causing total loss of refrigerant).
9. Blocked filter in the receiver drier.
10. Evaporator sensor disconnected?
11. Dual pressure switch faulty?
Note: Should a leak or low refrigerant be established as the cause, follow the procedures for Recovery-Recycle -Recharge, and
observe all refrigerant and oil handling instructions.
insufficient Cooing
1. Blower motor(s) sluggish.
2. Restricted blower inlet or outlet passage
3. Blocked or partially restricted condenser matrix or fins.
4. Blocked or partially restricted evaporator matrix.
5. Blocked or partially restricted filter in the receiver drier.
6. Blocked or partially restricted expansion valve.
7. Partially collapsed flexible pipe.
8. Expansion valve temperature sensor faulty (this sensor is integral with valve and is not serviceable).
9. Excessive moisture in the system.
10. Air in the system.
11. Low refrigerant charge.
May 1996 8-17