Part 4 of 4

SERVICE PORT VALVE CORE
The high pressure service port is located on the discharge line between the compressor and the condenser over the cooling fans, near the front of the engine compartment. The low pressure service port is located on the suction line, near the right strut tower.

Each of the service ports has a threaded plastic protective cap installed over it from the factory. After servicing the refrigerant system, always reinstall both of the service port caps.

The two refrigerant system service ports are used to charge/recover/recycle/evacuate and test the air conditioning refrigerant system. Unique service port coupler sizes are used on the R-134a system to ensure the refrigerant system is not accidentally contaminated with R-12 refrigerant or refrigerant system service equipment.

Fig.17 Heater Core:

HEATER CORE
The heater core is located in the HVAC housing. The core is a heat exchanger made of rows of tubes and fins.

Engine coolant is circulated through heater hoses to the heater core. As coolant flows through the heater core, heat is transferred to the heater core fins and tubes. Air directed through the heater core fins, picks up the heat. The temperature control door controls heater output air temperature by controlling the air flowing through the HVAC housing. The heater core cannot be repaired and must be replaced if damaged.

REFRIGERANT OIL
The refrigerant oil used in R-134a refrigerant systems is a synthetic-based, PolyAlkylene Glycol (PAG), wax-free lubricant. Mineral-based R-12 refrigerant oils are not compatible with PAG oils, and should never be introduced to an R-134a refrigerant system.

There are different PAG oils available, and each contains a different additive package. The TRS9O compressor used in this vehicle is designed to use an SP-15 PAG refrigerant oil. Use only refrigerant oil of this same type to service the refrigerant system.

After performing any refrigerant recovery or recycling operation, always replenish the refrigerant system with the same amount of the recommended refrigerant oil as was removed. Too little refrigerant oil can cause compressor damage and too much can reduce air conditioning system performance.

PAG refrigerant oil is much more hygroscopic than mineral oil, and will absorb any moisture it comes into contact with even moisture in the air. The PAG oil container should always be kept tightly capped until it is ready to be used. Recap the oil container immediately after use to prevent moisture contamination.

REFRIGERANT
The refrigerant used in this air conditioning system is a HydroFluoroCarbon (HFC), type R-134a. Unlike R-12, which is a ChloroFluoroCarbon (CFC), R-134a refrigerant does not contain ozone-depleting chlorine. R-134a refrigerant is a non-toxic, non-flammable, clear, and colorless liquefied gas.

Even though R-134a does not contain chlorine, it must be reclaimed and recycled just like CFC-type refrigerants. This is because R-134a is a greenhouse gas and can contribute to global warming.

R-134a refrigerant is not compatible with R-12 refrigerant in an air conditioning system. Even a small amount of R-12 added to an R-134a refrigerant system will cause compressor failure, refrigerant oil sludge or poor air conditioning system performance. In addition, the PolyAlkylene Glycol (PAG) synthetic refrigerant oils used in an R-134a refrigerant system are not compatible with the mineral-based refrigerant oils used in an R-12 refrigerant system.

R-134a refrigerant system service ports, service tool couplers and refrigerant dispensing bottles have all been designed with unique fittings to ensure that an R-134a system is not accidentally contaminated with the wrong refrigerant (R-12). There are also labels posted in the engine compartment of the vehicle and on the compressor identifying to service technicians that the air conditioning system is equipped with R-134a.