Heating and Air Conditioning: Description and Operation

CCOT Refrigeration System:

DESCRIPTION

The Cycling Clutch Orifice Tube (CCOT) refrigerant system is designed to cycle a fixed displacement compressor on and off to maintain desired cooling and to prevent evaporator freeze-up.

OPERATION

The refrigeration cycle (on and off operation of the compressor) is controlled by the Powertrain Control Module (PCM) and by a pressure cycling switch that senses low side system pressure as an indicator of evaporator temperature.

WARNING: Avoid breathing A/C Refrigerant-134a and lubricant vapor or 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 (or equivalent) (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 manufactures.

Like the coolant in the engine cooling system, the refrigerant is the substance in the air conditioning system flat absorbs, canies and then releases heat. Although various substances are used as refrigerants, past automotive air conditioning systems used a type called Refrigerant-12 (R-12).

This vehicle uses a new type of refrigerant called Refrigerant-134a (R134a). It is a non-toxic, non-flammable, clear, colorless, liquefied gas.

While the R-134a A/C system is very similar to an R-12 A/C system, the differences in the refrigerant, lubricants, and service equipment are important.

CAUTION:
- R-134a refrigerant is not compatible with R-12 refrigerant in an air conditioning system. R-12 in a R-134a system will cause compressor failure, refrigerant oil sludge or poor air conditioning system performance.

- Refrigerant-134a requires a charge of a special lubricating oil, Polyalkaline Glycol (PAG) refrigerant oil. GM (PAG) refrigerant oil will have a slight blue tint. The oil is hydroscopic (absorbs water from the atmosphere) and should be stored in closed containers.