heater fan coming on too much

[homer77]

1048704

1992 cheroke laredo, even when i just turn the car on(engine still cold) it seem that a fan connected with the car heater cycles on and off too much. it is only when i have the heat on. this has only just started to happen. what does this fan do and is it about to break down. [addsig]

 

[MudderChuck]

1048706

I´m not sure I undrstand the question, if you mean the electric fan by the radiator (six cylinder models) in the motor compartment or the heater fan itself, that blows warm air into the passenger compartment.

The electric fan in the motor compartment by the radiator, will come on, when the air conditioning pump comes on or when the radiator heats to about 220F. There is a position on the heater controls for window defrost, all the way to the right, in my 96 XJ, that will turn on the air-conditioner and use it as a heat pump to defrost the windows, the electric fan comes on also. A faulty air conditioning control could also be a problem.

If the fan comes on and the engine temp is normal and the heater controls are off. it is probably a faulty temperature switch in the radiator or a faulty relay.

Take a look in the motor compartment, when you start the car and watch the air conditioning pump for awhile, you can see the clutch (the part/pulley the belt goes around) move a little when it engages and disengages, if the fan comes on at the same time, you´l know where to start looking for the problem.[addsig]