Refrigerant: Description and Operation
REFRIGERATION CYCLERefrigeration Cycle:
Refrigerant Flow
The refrigerant flows in the standard pattern. Refrigerant flows through the compressor, condenser, liquid tank, expansion valve, evaporator, and back to the compressor. The refrigerant evaporation through the evaporator coil is controlled by an externally equalized expansion valve, located inside the evaporator case.
Freeze Protection
The compressor cycles on and off to maintain the evaporator temperature within a,specified range. When the evaporator coil temperature falls below a specified point, the thermo control amplifier interrupts the compressor operation. When the evaporator coil temperature rises above the specification, the thermo control amplifier allows compressor operation.
Refrigerant System Protection
Dual Pressure Switch
The refrigerant system is protected against excessively high or low pressure. The protection is effected by a dual pressure switch located on the liquid tank. If the pressure falls out of specifications, the switch opens to interrupt compressor operation.
Pressure Relief Valve
The refrigerant system is also protected by a pressure relief valve located on the flexible high pressure hose near the compressor. When the pressure of refrigerant in the system increases to an abnormal level [more than 3,727 kPa (38 kg/sq.cm, 540 psi)], the release port on the pressure relief valve automatically opens and releases refrigerant into the atmosphere.
Refrigerant-134a (R-134a)
The refrigerant is the substance in the air conditioning system that absorbs, carries and releases heat. Although various substances are used as refrigerants in other types of refrigeration systems, past automotive air conditioning systems used Refrigerant-12 (R-12).
This vehicle uses Refrigerant-134a (R-134a). R-134a has the following features:
- Non-toxic
- Non-flammable
- Clear
- Colorless
- Liquefied gas
Refrigerant-134a carries a charge of a special lubricant, Polyalkaline Glycol (PAG) refrigerant oil. PAG refrigerant oil has a slight blue tint. The oil is hydroscopic (absorbs water from the atmosphere). Store R-134a in closed containers.
CAUTION: Avoid breathing A/C Refrigerant-134a and lubricant vapor and mist Exposure may irritate eyes, nose and throat. To remove R-134a from the A/C system, use service equipment certified to meet the requirements of SAE J2210 (R-134a recycling equipment). If accidental system discharge occurs, ventilate work area before resuming service. Additional health and safety information may be obtained from refrigerant and lubricant manufacturers.
NOTE: R-134a refrigerant is not compatible with R-12 refrigerant in an air conditioning system. R-12 in a R-134a system will cause A/C compressor failure, refrigerant oil sludge, or poor air conditioning system performance.