Air conditioning system - general information and precautions

Cooling, heating, and air conditioning systems / Air conditioning system - general information and precautions

General information
The air conditioning system consists of a condenser mounted in front of the radiator, an evaporator mounted adjacent to the heater matrix, a compressor mounted on the engine, an accumulator/dehydrator, and the plumbing connecting all of the above components - this contains a choke (or “venturi”) mounted in the inlet to the evaporator, which creates the drop in pressure required to produce the cooling effect (see illustration).

11.1 Air conditioning system components

1 Quick-release Schrader valve-type coupling - high-pressure side 2 Quick-release Schrader valve-type coupling - low-pressure side 3 Pressure-cycling switch - low-pressure side 4 Accumulator/dehydrator 5 Compressor
6 Condenser
7 Pressure-regulating switch - high-pressure side

A blower fan forces the warmer air of the passenger compartment through the evaporator core (rather like a radiator in reverse), transferring the heat from the air to the refrigerant. The liquid refrigerant boils off into low-pressure vapour, taking the heat with it when it leaves the evaporator.

Precautions
Warning: The air conditioning system is under high pressure.

Do not loosen any fittings or remove any components until after the system has been discharged. Air conditioning refrigerant should be properly discharged into an approved type of container, at a dealer service department or an automotive air conditioning repair facility capable of handling R134a refrigerant. Always wear eye protection when disconnecting air conditioning system fittings.

When an air conditioning system is fitted, it is necessary to observe the following special precautions whenever dealing with any part of the system, its associated components, and any items which necessitate disconnection of the system:
(a) While the refrigerant used - R134a - is less damaging to the environment than the previously-used R12, it is still a very dangerous substance. It must not be allowed into contact with the skin or eyes, or there is a risk of frostbite. It must also not be discharged in an enclosed space - while it is not toxic, there is a risk of suffocation. The refrigerant is heavier than air, and so must never be discharged over a pit.

(b) The refrigerant must not be allowed to come in contact with a naked flame, otherwise a poisonous gas will be created - under certain circumstances, this can form an explosive mixture with air. For similar reasons, smoking in the presence of refrigerant is highly dangerous, particularly if the vapour is inhaled through a lighted cigarette.

(c) Never discharge the system to the atmosphere - R134a is not an ozonedepleting ChloroFluoroCarbon (CFC) as is R12, but is instead a hydrofluorocarbon, which causes environmental damage by contributing to the “greenhouse effect” if released into the atmosphere.

(d) R134a refrigerant must not be mixed with R12; the system uses different seals (now green-coloured, previously black) and has different fittings requiring different tools, so that there is no chance of the two types of refrigerant becoming mixed accidentally.

(e) If for any reason the system must be disconnected, entrust this task to your Ford dealer or a refrigeration engineer.

(f) It is essential that the system be professionally discharged prior to using any form of heat - welding, soldering, brazing, etc - in the vicinity of the system, before having the vehicle oven-dried at a temperature exceeding 70°C after repainting, and before disconnecting any part of the system.