A/C Refrigerant System Operation

MANDATORY PROCEDURE
Prompted by environmental concerns, Ford Motor Company is now producing vehicles equipped with non-chlorofluorocarbon (non-CFC) air conditioning systems. The new refrigerant used is R-134a, a hydrofluorocarbon that has no chlorine molecule, which destroys the atmosphere's ozone layer. R-134a will eventually replace R-12 as the refrigerant for all Ford climate control systems. R-134a systems operate and function in the same manner as R-12 systems except for minimal operating pressure differences and component variations.

These vehicles use the R-134a A/C system. This system uses different components, refrigerant, and refrigerant oil than the traditional Ford R-12 A/C systems used in previous years.

It is important to understand that R-134a and R-12 air-conditioning systems are not entirely the same. They have components that are slightly different from one another and in some cases service requirements are also different. However, the most important thing to understand is that R-134a refrigerant, refrigerant oil, and components can only be used on R-134a systems.

Also, R-134a systems require the use of dedicated special service tools and equipment. R-134a special service tools and equipment that come in contact with the R-134a refrigerant or refrigerant oil can only be used on R-134a A/C systems. R-12 special service tools and equipment cannot be used on R134a A/C systems.

A/C REFRIGERANT SYSTEM OPERATION
These vehicles use a Clutch Cycling Orifice Tube - Manual A/C Heater system.

The air-conditioning system consists of:
- A/C compressor.
- A/C condenser core.
- A/C evaporator core orifice.
- A/C evaporator core.
- Suction accumulator/drier.
- A/C cycling switch.
- A/C pressure cut-off switch.
- Climate control assembly.
- Refrigerant lines.

This system is designed to cycle the A/C compressor on and off to maintain desired cooling and prevent the A/C evaporator core from freezing. Passenger compartment comfort is maintained by the mix of cooled and heated air as controlled by the temperature blend lever on the climate control assembly.

System operation is controlled by the A/C evaporator core orifice and the A/C cycling switch.




REFRIGERANT FLOW
The A/C compressor pulls in low-pressure vapor and pumps out high-pressure vapor to the A/C condenser core. The high-pressure vapor entering the A/C condenser core is cooled by outside air passing over the A/C condenser core cooling fins. This heat loss causes the high-pressure vapor to become high-pressure liquid. The high-pressure liquid enters the condenser to evaporator tube where it is restricted by the A/C evaporator core orifice. This restriction in the refrigerant flow allows the A/C compressor discharge to build pressure in the A/C condenser core while the A/C compressor suction lowers the pressure in the A/C evaporator core. Low-pressure liquid from the A/C condenser core then enters the A/C evaporator core where hot, humid air passes over the A/C evaporator core coils. The A/C evaporator core coils remove the heat and humidity from the air being circulated in the passenger compartment. When the low-pressure liquid absorbs the heat in the A/C evaporator core, it again becomes a low-pressure gas. The low-pressure gas then enters the suction accumulator/drier. The suction accumulator/drier prevents any excess low-pressure liquid from reaching the A/C compressor. It accomplishes this by allowing any low-pressure liquid leaving the A/C evaporator core to vaporize before reaching the A/C compressor.

REFRIGERANT SYSTEM TESTS
Ford Motor Company now produces new cars with R-134a fluorescent tracer dye incorporated into the A/C system.