Part 2 of 2

Fig.11 HVAC Outlets:

AIR FLOW DISTRIBUTION
Based upon the system mode selected, conditioned air can exit the standard heater-only or optional heater-A/C unit housing through one or a combination of the three main housing outlets: defrost, panel or floor. The defrost outlet is located on the top of the housing, the panel outlet is located on the face of the housing and the floor outlet is located on the bottom of the housing. Once the conditioned air exits the unit housing, it is further directed through molded plastic ducts to the various outlets in the vehicle interior. These outlets and their locations are as follows:
- Defroster Outlet - A single large defroster outlet is located in the center of the instrument panel top cover, near the base of the windshield.
- Side Window Demister Outlets - There are two side window demister outlets, one is located at each outboard end of the instrument panel top cover, near the belt line at the A-pillars.
- Panel Outlets - There are four panel outlets in the instrument panel, one located near each outboard end of the instrument panel facing the rear of the vehicle and two located near the top of the instrument panel center bezel.
- Front Floor Outlets - There are four front floor outlets, two located above each side of the floor panel center tunnel near the dash panel.
- Rear Floor Outlets - There are two rear floor outlets, one located on each side of the floor panel center tunnel near the front of each rear seat foot well.

The defroster outlet receives airflow from the unit housing through the molded plastic defroster duct, which is snapped onto the unit housing defroster outlet and secured by two tabs to mounting slots in the dash panel. The airflow from the defroster outlet is directed by fixed vanes in the defroster outlet grille and cannot be adjusted. The defroster outlet grille is integral to the instrument panel top cover.

The side window demister outlets receive airflow from the unit housing through the air outlet distribution duct, two molded plastic demister hoses and, on the right side only, an intermediate duct. The air outlet distribution duct is secured to the instrument panel with screws and receives airflow through the panel outlet of the unit housing. The airflow from the side window demister outlets is directed by fixed vanes in the demister outlet grilles and cannot be adjusted. The side window demister outlet grilles are integral to the instrument panel top cover.

The panel outlets also receive airflow from the unit housing through the air outlet distribution duct. Molded plastic panel outlet ducts and, on the left side only an intermediate elbow direct airflow from the distribution duct to the outboard panel outlets, while a center air outlet duct directs airflow from the distribution duct to the two center panel outlets. The airflow from each of the panel outlets is adjustable. A knob in the center of each panel outlet grille is used in a joystick fashion to adjust a center diffuser that changes the airflow direction, and a knob on the outer edge of each panel outlet grille opens or closes a shutter to turn airflow ON or OFF through that outlet.

The front and rear floor outlets receive airflow from the unit housing through the floor distribution duct. The front floor outlets are integral to the molded plastic floor distribution duct, which is secured to the bottom of the unit housing. A molded plastic rear seat duct elbow is fitted to the bottom of the floor distribution duct and directs airflow through a molded plastic duct beneath the carpet on the right side of the floor panel center tunnel to the right rear floor outlet. The right floor duct also features a crossover fitting that joins the right floor duct to the left floor duct over the top of the floor panel center tunnel to direct airflow to the left rear floor outlet. None of the floor outlets can be adjusted.

PLUMBING

A/C Compressor
The compressor used on this vehicle is a Nippondenso 10S17. This compressor uses an aluminum swash plate, teflon coated pistons and aluminum sleeveless cylinder walls.

Excessive noise that occurs when the air conditioning is being used may be caused by:
- Loose bolts
- Mounting brackets
- Loose compressor clutch
- Excessive high refrigerant operating pressure

Verify the following before compressor repair is performed:
1. Compressor drive belt condition
2. Proper refrigerant charge
3. Thermal expansion valve (TXV) operating correctly
4. Head pressure is normal

Compressor Front Shaft Seal
The compressor front shaft seal is not serviceable. If a leak is detected at the shaft seal, the compressor must be replaced as a unit.

The compressor is driven by the engine through an electric clutch, drive pulley and belt arrangement. The compressor is lubricated by refrigerant oil that is circulated throughout the refrigerant system with the refrigerant.

The compressor draws in low-pressure refrigerant vapor from the evaporator through its suction port. It then compresses the refrigerant into a high-pressure, high-temperature refrigerant vapor. The compressor pumps high-pressure refrigerant vapor to the condenser through the compressor discharge port.

Fig.3 Condenser:

A/C CONDENSER
The condenser is integral to a cooling module which includes the radiator, the electric cooling fan, the fan shroud, air seals and an automatic transmission oil cooler on models so equipped. The cooling module is located in the air flow in the front of the engine compartment behind the front grille.

The condenser cannot be repaired or adjusted and, if faulty or damaged, it must be replaced. The cooling module must be removed from the vehicle in order to access the condenser for service.

The condenser is a heat exchanger that allows the high-pressure refrigerant gas being discharged by the compressor to give up its heat to the air passing over the condenser fins. When the refrigerant gas gives up its heat, it condenses. When the refrigerant leaves the condenser, it has become a high-pressure liquid refrigerant.

The volume of air flowing over the condenser fins is critical to the proper cooling performance of the air conditioning system. Therefore, it is important that there are no objects placed in front of the radiator grille openings in the front of the vehicle or foreign material on the condenser fins that might obstruct proper air flow. Also, any factory-installed air seals or shrouds must be properly reinstalled following radiator or condenser service.

Fig.5 A/C Compressor Lines:

A/C DISCHARGE LINE
The discharge line is the line that goes from the compressor to the condenser. It has no serviceable parts except the rubber O-rings . If the line is found to be leaking or is damaged it must be replaced as an assembly.

Fig.7 Evaporator:

A/C EVAPORATOR
The evaporator is located in the heater-A/C unit housing, under the instrument panel. The evaporator is positioned in the heater-A/C housing so that all air that enters the housing must pass over the fins of the evaporator before it is distributed through the system ducts and outlets. However, air passing over the evaporator fins will only be conditioned when the compressor is engaged and circulating refrigerant through the evaporator tubes.

The heater-A/C unit housing must be removed from the vehicle to access the evaporator for service. The evaporator cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

Refrigerant enters the evaporator from the variable orifice valve as a low-temperature, low-pressure liquid. As air flows over the fins of the evaporator, the humidity in the air condenses on the fins, and the heat from the air is absorbed by the refrigerant. Heat absorption causes the refrigerant to boil and vaporize. The refrigerant becomes a low-pressure gas when it leaves the evaporator.

A/C VARIABLE ORIFICE TUBE
A Variable Orifice Valve (VOV) is installed in the liquid line between the outlet of the condenser and the inlet of the evaporator. The inlet end of the Variable Orifice Valve has a nylon mesh filter screen, which filters the refrigerant and helps to reduce the potential for blockage of the metering orifices by refrigerant system contaminants. The outlet end of the tube has a nylon mesh diffuser screen. The O-rings on the plastic body of the VOV seal the tube to the inside of the liquid line and prevent refrigerant from bypassing the metering orifices.

The VOV is only serviced as an integral part of the liquid line. The VOV cannot be adjusted or repaired and, if faulty or plugged, the liquid line unit must be replaced.

The VOV meters the flow of liquid refrigerant into the evaporator coil. The VOV contains two orifices which work in parallel. The fixed orifice works along with the variable port to regulate refrigerant expansion in the evaporator in a manner that is suitable for most operating conditions. The high-pressure liquid refrigerant from the condenser expands into a low-pressure liquid/vapor as it passes through the metering orifices and diffuser screen of the VOV

The VOV varies the flow of refrigerant in response to the temperature of the refrigerant exiting the condenser. A thermostatic bimetal coil wrapped around the valve body is affected by the refrigerant temperature changes, which opens or closes the variable port to regulate refrigerant flow. As the refrigerant temperature increases, the variable port is progressively closed. A higher temperature (while idling) produces more restriction. A lower temperature (at road speed) produces less restriction.

Fig.12 Accumulator - Typical:

ACCUMULATOR
The accumulator is mounted in the engine compartment between the evaporator outlet and the compressor suction port. An integral mounting bracket is used to secure the accumulator to the right side rail with a screw. Two connectors of the suction and liquid line assembly are sealed to an integral connector block on the top of the accumulator canister with rubber O-ring seals and secured there with two screws. A threaded fitting on the top of the accumulator canister provides the port through which the low pressure clutch cycling switch monitors the refrigerant system pressures.

The accumulator cannot be repaired and, if faulty or damaged, it must be replaced. The suction and liquid line assembly the rubber O-rings and the low pressure clutch cycling switch are available for service replacement.

Refrigerant enters the accumulator canister as a low pressure vapor through the inlet tube. Any liquid, oil-laden refrigerant falls to the bottom of the canister, which acts as a separator. A desiccant bag located inside the accumulator canister absorbs any moisture which may have entered and become trapped within the refrigerant system.

Fig.14 Heater Core:

HEATER CORE RH DRIVE
The heater core is located in the heater-A/C unit housing, under the instrument panel. It is a heat exchanger made of rows of tubes and fins. One end of the core is fitted with a molded plastic tank that includes the integral heater core hose nipples.

Engine coolant is circulated through heater hoses to the heater core at all times. As the coolant flows through the heater core, heat removed from the engine is transferred to the heater core fins and tubes. Air directed through the heater core picks up the heat from the heater core fins. The blend air door allows control of the heater output air temperature by controlling how much of the air flowing through the heater-A/C housing is directed through the heater core. The blower motor speed controls the volume of air flowing through the heater-A/C housing.

The heater core cannot be repaired and, if faulty or damaged, it must be replaced. Refer to Cooling System for more information on the engine cooling system, the engine coolant and the heater hoses.

Fig.21 Heater Core:

HEATER CORE
The heater core is located in the heater A/C unit housing, under the instrument panel. It is a heat exchanger made of rows of tubes and fins. One end of the core is fitted with a molded plastic tank that includes the integral heater core hose nipples.

Engine coolant is circulated through heater hoses to the heater core at all times. As the coolant flows through the heater core, heat removed from the engine is transferred to the heater core fins and tubes. Air directed through the heater core picks up the heat from the heater core fins. The blend air door allows control of the heater output air temperature by controlling how much of the air flowing through the heater-A/C housing is directed through the heater core. The blower motor speed controls the volume of air flowing through the heater-A/C housing.

The heater core cannot be repaired and, if faulty or damaged, it must be replaced. Refer to Cooling System for more information on the engine cooling system, the engine coolant and the heater hoses.

LIQUID LINE
The liquid line is the line that goes from the condenser to the receiver-drier. It has no serviceable parts except the rubber O-rings . If the line is found to be leaking or is damaged it must be replaced as an assembly.

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-Hammable, 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.

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 10S15 and 10S17 compressors used in this vehicle is designed to use an ND-8 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. After use, recap the oil container immediately to prevent moisture contamination.

SUCTION LINE
The suction line is the large line that connects to the expansion valve and goes to the compressor. It also has a small line that goes to the filter/drier. The suction line uses a gasket on the expansion valve side and rubber O-rings on all other connections.

There are no serviceable parts on the suction line other than the rubber O-rings and expansion valve gasket. If the line is found to be leaking or is damaged it must be replaced as an assembly.

The refrigerant lines used for this vehicle are common between the two optional engines in order to reduce complexity The following refrigerant lines are available for service replacement on this vehicle:

Fig.33 A/C Refrigerant Lines - Compressor:

- Discharge line - The discharge line is a flexible hose type line that is connected from the discharge port of the compressor to the inlet (upper fitting) of the condenser. It has no serviceable parts except the rubber O-ring seals used on the fittings at each end of the line. If the discharge line is damaged or faulty, it must be replaced.
- Liquid line - The liquid line is a flexible hose type line that is connected between the outlet (lower fitting) of the condenser and the mid-line connector block of the suction and liquid line assembly. The liquid line also contains the variable orifice valve. It has no serviceable parts except the rubber O-ring seals used on the fittings at each end of the line. If the liquid line or the variable orifice valve are damaged or faulty, the liquid line unit must be replaced.
- Suction line - The suction line is a flexible hose type line that is connected between the mid-line connector block of the suction and liquid line assembly and the suction port of the compressor. It has no serviceable parts except the rubber O-ring seals used on the fittings at each end of the line. If the suction line is damaged or faulty it must be replaced.

Fig.34 A/C Service Ports:

- Suction and liquid line assembly - The suction and liquid line assembly is a formed tubing type line assembly that includes the mid-line connector block, a connector block for the evaporator, inlet and outlet line fittings for the accumulator and both A/C service ports. The A/C service port caps, the A/C service port valve cores, the gasket used to seal the connector block at the evaporator and the rubber O-ring seals for the line fittings at the accumulator are all available for service replacement. If any other part of the suction and liquid line assembly is damaged or faulty the assembly must be replaced.

High pressures are produced in the refrigerant system when the air conditioning compressor is operating. Extreme care must be exercised to make sure that each of the refrigerant line connections is pressure-tight and leak free. It is a good practice to inspect all flexible hose refrigerant lines at least once a year to make sure they are in good condition and properly routed.

CONDENSATION DRAIN TUBE
Condensation that accumulates in the evaporator housing is drained by a tube through the dash and on to the ground. This tube must be kept open to prevent condensate water from collecting in the bottom of the housing.

The tapered end of the drain tube is designed to keep contaminants from entering the heater A/C unit housing. If the tube is pinched or blocked, condensate cannot drain, causing water to back up and spill into the passenger compartment. It is normal to see condensate drainage below the vehicle. If the tube is damaged, it should be replaced.

Fig.39 A/C Service Port Valves:

SERVICE PORT VALVE CORE
A/C Service Port Valve Cores
The A/C service port valve cores are serviceable items. The high side valve is located on the filter-drier, and the low side valve is situated on the suction line, near the washer fluid reservoir filler.