Jeep Cherokee

 Service Manual

Cooling system » Description and operation
Electric cooling fan

DESCRIPTION

Vehicles equipped with a 2.5L/4.0L engine and air conditioning and 4.0L vehicles equipped with the "max" cooling package also have an electrical cooling fan. The fan is controlled by the cooling fan relay, which is located in the power distribution center (PDC) (Fig. 15). For the location of relay within the PDC, refer to the label on PDC cover.

The electric fan on the 2.5L engine equipped vehicles is considered the primary fan (low to moderate ambient conditions) and is energized when the JTEC receives input from the coolant temperature sensor or the a/c system and supplies ground to the cooling fan relay.

The cooling fan motor is protected by a 40 amp maxi-fuse located in the PDC. The fan relay is protected by a 15 amp fuse located in the junction block.

OPERATION

Electric cooling fan 2.5L: When air conditioning is not requested, the electric fan will not come on unless the coolant temperature is at least 103 C (218 F), at which time the fan will come on and remain on until the coolant temperature drops to 99 C (210 F) or below. When air conditioning is requested (including defroster operation), the fan will cycle on and off in conjunction with the A/C compressor unless the coolant temperature is at least 97 C (207 F), at which time the fan will come on and remain on until the coolant temperature drops to 93 C (199 F) or below. Then, the cycle fan operation will resume. When the fan is scheduled to be on, the powertrain control module (PCM) provides a ground path for the fan relay. This ground is provided to the cooling fan relay through pin C2 of PCM connector C3. Battery voltage is then applied to the fan through the relay. When the fan is scheduled to be off, the PCM opens the ground path to the relay. This will prevent the cooling fan from being energized.

Fig. 14 Electric Cooling Fan

1 - (LHD)
2 - (RHD)
3 - VISCOUS FAN SHROUD
4 - ELECTRIC FAN MODULE
5 - ISOLATOR
6 - RADIATOR
7 - LOWER CROSSMEMBER
8 - U-NUT
9 - UPPER CROSSMEMBER

Fig. 15 Power Distribution Center (PDC)

1 - RIGHT FENDER
2 - BATTERY
3 - POWER DISTRIBUTION CENTER

Electric cooling fan 4.0L: With or without A/C request the electric fan will come on only when the coolant temperature is at least 106 C (223 F), and will remain on until the coolant temperature drops to 103 C (217 F) or below. Regardless of coolant temperature, When air conditioning system pressures reach 2068.5 6 138 kPa (300 6 20 psi) the electric fan will engage and continue to run until the A/C system pressure drops to 1620.3 kPa (235 psi) minimum, then the electric fan will shut off.

Cooling system

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Coolant reserve/overflow system

Cooling system fans

Block heater

Thermostat

Radiator

Radiator pressure cap

Water pump

Hose clamps

Viscous fan drive

Electric cooling fan