Hello I have 2001 grand cherokee 4,7 litre.power everything. the fan runs at all the different speeds i turn the switch to. i can hear it change speeds. the defrost, the face, the combo, and the feet, all change directions as i move the switch. the problems is that the air flow is really slow out of the different vents, i can tell the air is going to where i change the selector switch to. please help

Only overheating at idle while standing still is most probably a cooling fan problem. If you have the electrical cooling fan, then first check its fuse. If ok, than there are two separate relays (high speed and low speed) in the power distribution center under the hood. (this is for 2004 model only). Swap both relays, it can be that the low speed relay is bad. If this helped, than you will have to replace the bad relay. If this didn´t help, then put 12V directly on the fan motor (watch hands and loose clothing) to be sure the motor is not bad.

Do you hear a change in noise when you change the fan speeds? Its more than likely a blower motor thats inoperative. Start by seeing if ANY of the speeds work. If none of them work, its probably not the switch or the resistor. Try jumping battery voltage to the blower motor and see if it turns on. If not then you need a blower motor. Hope this helps

Changing the thermostat is the standard answer. Make sure the cooling fan(s) come on when it reaches operating temperature. The fans won't make much difference if the car is moving, but standing still, they can make a great difference. Blow out the radiator core with compressed air from the engine side to get rid of accumulated bugs and other debris. Hope this helps!

There is the coolant sensor that tells the computer the temp,and the computer sends a signal to the cooling fan relays,and the relay turns the cooling fans on,and off,if the system is low on coolant,or has air in the cooling system,then the cooling fans would not come on,or the sensor is bad,if this was at all helpful,please rate,thank you.

My moms fan switch went on her 01 gr cherokee and had the whole fan and relay replace, when is doesn't come on the fan motor is bad and won't regulate power, so the mechanic says, Please rate is thanx

If it was overheating at freeway speed then it is a clogged radiator. Another cause of overheating is a timing that is retarded. These can be caused by worn timing components etc, although a possiblity it is highly unlikely on your car.

This means your thermostat is bad. Needs to be replaced. Also do coolant flush.

Alot of people have the same problem with the fan switch and blown bulbs. There really is no fix for this. Jeep really screwed up when designing the heater control assembly. The cheapest solution is to buy another unit off Ebay. Can always go to the dealer but be ready to PAY for there mistakes.

Have you tested the fan, use a set of clip leads and supply 12 volts of battery power to the fan to see if it runs, another test is to disconnect the engine coolant temp fan switch, this sends the system into default and the fan will run.

I don't know if this will help anyone, but i had a issue with my jeep running hot and check engine light coming on as well. After alot of trips to different shops - the last one found that there were two senors in the engine for the fan that need to be changed. Everyone would aways fine the one up top but not the second one. After that, have not had any other problems like it since.