Engine Cooling System & Automatic Transmission Cooling System: Overview Chrysler Pacifica CS

DESCRIPTION - COOLING SYSTEM

The cooling system components consist of a radiator, electric fan motors, shroud, pressure cap, thermostat, transmission oil cooler, water pump, hoses, clamps, coolant, and a coolant pressure container to complete the circuit.

DESCRIPTION - HOSE CLAMPS

The cooling system uses spring type hose clamps. If a spring type clamp replacement is necessary, replace with the original Mopar® equipment spring type clamp.

Scheme 6

OPERATION - COOLING SYSTEM

The engine cooling systems primary purpose is to maintain engine temperature in a range that will provide satisfactory engine performance and emission levels under all expected driving conditions. It also provides hot water (coolant) for heater performance and cooling for automatic transmission oil. It does this by transferring heat from engine metal to coolant, moving this heated coolant to the radiator, and then transferring this heat to the ambient air.

1. When engine is cold: thermostat is closed, cooling system has no flow through the radiator. The coolant bypass flows through the engine only.
2. When engine is warm: thermostat is open, cooling system has bypass flow and coolant flow through radiator.

DESCRIPTION - ENGINE COOLANT

The cooling system is designed around the coolant. The coolant must accept heat from engine metal, in the cylinder head area near the exhaust valves and engine block. Then coolant carries the heat to the radiator where the tube/fin radiator can transfer the heat to the air.

The use of aluminum cylinder blocks, cylinder heads, and water pumps requires special corrosion protection. Mopar® Antifreeze/Coolant, 5 Year/100,000 Mile Formula (MS-9769), or the equivalent ethylene glycol base coolant with hybrid organic corrosion inhibitors (called HOAT, for Hybrid Organic Additive Technology) is recommended. This coolant offers the best engine cooling without corrosion when mixed with 50% Ethylene Glycol and 50% distilled water to obtain a freeze point of -37°C (-35°F). If it loses color or becomes contaminated, drain, flush, and replace with fresh properly mixed coolant solution.

The green coolant MUST NOT BE MIXED with the orange or magenta coolants. When replacing coolant the complete system flush must be performed before using the replacement coolant.

DESCRIPTION

The coolant recovery/reserve system container is mounted in the engine compartment. The container is made of plastic.

OPERATION

The coolant recovery system works with the pressure cap to use thermal expansion and contraction of the coolant to keep the coolant free of trapped air. Provides a convenient and safe method for checking coolant level and adjusting level at atmospheric pressure without removing the pressure cap. It also provides some reserve coolant to cover deaeration, evaporation, or boiling losses.

RADIATOR FAN OPERATION CHART

The engine block heater is available as an optional accessory on all models. The heater is operated by ordinary house current (110 Volt A.C.) through a power cord located behind the radiator grille. This provides easier engine starting and faster warm-up when vehicle is operated in areas having extremely low temperatures. The heater is mounted in a core hole (in place of a core hole plug) in the engine block, with the heating element immersed in coolant.

The block heater element is submerged in the cooling system's coolant. When electrical power (110 volt A.C.) is applied to the element, it creates heat. This heat is transferred to the engine coolant. This provides easier engine starting and faster warm-up when vehicle is operated in areas having extremely low temperatures.

The engine coolant temperature sensor threads into a coolant passage on lower intake manifold near the thermostat. New sensors have sealant applied to the threads. (Scheme 7)

Scheme 7

The cooling system utilizes both worm drive and spring type hose clamps. If a spring type clamp replacement is necessary, replace with the original Mopar® equipment spring type clamp. To identify size of spring hose clamps, the size in millimeters has been stamped on each clamp. (Scheme 8)

Scheme 8

The worm type hose clamp uses a specified torque value to maintain proper tension on a hose connection.

The spring type hose clamp applies constant tension on a hose connection. To remove a spring type hose clamp, use Special Tool 6094 or equivalent, constant tension clamp pliers. (Scheme 9)to compress the hose clamp.

Scheme 9

Scheme 10

Scheme 11

Scheme 12

1. Disconnect negative cable from battery.
2. Discardge the A/C system (Refer to «STANDARD PROCEDURE»(ref-245452-S23385733282006110200000) ).
3. Remove the front fascia «FRONT FASCIA»(ref-245440-S14371693552006110200000).
4. Drain the cooling system. «(Refer to COOLING - STANDARD PROCEDURE)»(ref-245448-S20805593812006110200000).
5. Disconnect the radiator fan electrical connectors.
6. Disconnect coolant reserve/recovery hose.
7. Remove A/C lines «A/C CONDENSER»(ref-245452-S17903156682006110200000).
8. Remove the auxiliary transmission cooler hoses.
9. Remove the pushpins and the upper radiator seal.
10. Remove the pushpins and the LH and RH radiator seal. (Scheme 10) 1 - RH RADIATOR SEAL 2. - PUSHPIN 3 - UPPER RADIATOR SEAL
11. Remove the A/C condenser side brackets to radiator attaching screws. (Scheme 11) Separate the condenser from the radiator by lifting upward to disengage from lower mounts. (Scheme 11) Allow the condenser to rest in front of radiator. 1 - SCREW - A/C CONDENSER SIDE BRACKET TO RADIATOR 2 - LOWER MOUNT 3 - A/C CONDENSER
12. Remove the upper and lower radiator hoses.
13. Radiator can now be lifted free from engine compartment. Care should be taken not to damage radiator cooling fins or water tubes during removal. (Scheme 12)1 - RADIATOR MODULE 2 - AUXILIARY TRANSMISSION COOLER HOSES 2 - AUXILIARY TRANSMISSION COOLER
14. Remove the auxiliary transmission from the radiator module.
15. Remove the cooling fan assembly from the radiator module.

The cooling system pressure cap is located on the coolant pressure container. The cap construction includes; stainless steel swivel top, rubber seals, and retainer, main spring, and a spring loaded valve. (Scheme 13)

Scheme 13

The cooling system is equipped with a pressure cap that releases excessive pressure; maintaining a range of 97-124 kPa (14-18 psi).

The cooling system will operate at higher than atmospheric pressure. The higher pressure raises the coolant boiling point thus, allowing increased radiator cooling capacity.

There is also a vent valve in the center of the cap. This valve also opens when coolant is cooling and contracting, allowing the coolant to return to cooling system from coolant reserve system tank by vacuum through a connecting hose. If valve is stuck shut, or the coolant recovery hose is pinched, the radiator hoses will be collapsed on cool down. Clean the vent valve. (Scheme 13)and inspect coolant recovery hose routing, to ensure proper sealing when boiling point is reached.

The gasket in the cap seals the filler neck, so that vacuum can be maintained, allowing coolant to be drawn back into the radiator from the reserve tank. If the gasket is dirty or damaged, a vacuum may not be achieved, resulting is loss of coolant and eventual overheating due to low coolant level in radiator and engine.

The radiator fan relay is a solid state type and is located on the back of the bumper beam. Refer to SYSTEM WIRING DIAGRAMS for a circuit schematic.

The solid state radiator fan relay is controlled by the Powertrain Control Module (PCM) by way of a Pulse Width Modulated (PWM) signal. The relay control circuit supplies a 12 volt signal to the PCM. The PCM then pulses the ground circuit to achieve fan on time. The relay provides a voltage to the fan motors which is proportional to the pulse width it receives from the PCM. The duty cycle ranges from 50% for low speed operation, then ramps-up to 100% for high speed operation. This fan control system provides infinitely variable fan speeds, allowing for improved fan noise, A/C performance, better engine cooling, and additional vehicle power.

To control operation of the relay, the PCM looks at inputs from

1. Engine coolant temperature
2. A/C pressure transducer
3. Ambient temperature from the body controller
4. Vehicle speed
5. Transmission oil temperature

The PCM uses these inputs to determine when the fan should operate and at what speed.

The 3.5L water pump has a die cast aluminum housing and a plastic swept vane impeller. It bolts directly to the right rear timing belt cover using an O-ring for sealing. see scheme 38 The water pump is driven by the engine timing belt.

The transmission oil cooler is an oil-to-air type cooler that is mounted on the front of the radiator and in front of the of the A/C condenser. The transmission oil cooler is equipped with quick connect fittings for the transmission oil cooler lines. Use only approved transmission oil cooler hoses that are molded to fit the space available. (Scheme 14)

Scheme 14

Transmission oil is supplied to the oil-to-air- transmission cooler mounted on front side of the radiator. Oil is then returned to the transmission from the external oil cooler. (Scheme 14)

Scheme 15

1. Remove dust cap by pulling it straight back off of quick connect fitting. (Scheme 15)
2. Place disconnect tool Special Tool 8875A onto transmission cooler line with the fingers of the tool facing the quick connect fitting.
3. Slide disconnect tool down the transmission line and engage the fingers of the tool into the retaining clip. When properly engaged in the clip, the tool will fit flush against the quick connect fitting.
4. Rotate the disconnect tool 60° to expand the retaining clip.
5. While holding the disconnect tool against the quick connect fitting, pull back on the transmission cooler line to remove.

Scheme 16

1. Align transmission cooler line with quick connect fitting while pushing straight into the fitting.
2. Push in on transmission cooler line until a "click" is heard or felt. (Scheme 16)
3. Slide dust cap down the transmission cooler line and snap it over the quick connect fitting until it is fully seated and rotates freely. (Scheme 16) Dust cap will only snap over quick connect fitting when the transmission cooler line is properly installed.

Note. If dust cap will not snap into place, repeat assembly step #2.