2000 Jeep Grand Cherokee Blower on A/C Goes On & Off.

bingo !

http://www.fixkick.com/look/odds-ends/jeep/2000GC-heater-motor.JPG

Either something was mis-wired, or you have a shorted blower motor or a cut in the wire insulation that is shorting to ground. I'm amazed that a 40 Amp fuse is used for the blower motor - that is a lot of current for a motor that size. (13.6 Volts times 40 Amps is 544 Watts for a fan?! There must be some other stuff on that circuit or somebody put in an oversized fuse.)

check your blower hoses to see if one or more have come loose or got redirected or the selector switch isn't functioning properly (is it blowing better on defrost as opposed to floor vents, or forward vents, etc.)
Good luck

cut wire to a/c pump in proses

The blower fan relay is located in the fuse box on the driver's side fender-well. A Jeep Cherokee uses an electric fan as an auxiliary fan for engine cooling and for cooling the air conditioning condenser when the air conditioning is in operation. A radiator temperature-sensing switch that activates the fan relay at 198 degrees F turns the fan on and controls its operation. The temperature drops when the vehicle is in motion and the switch turns the fan off. When the air conditioning system is in operation, the air conditioning relay supplies power to the fan relay via a fan diode downstream from the ignition switch. This diode activates the fan relay and keeps the fan operating as long as the air conditioning is on. Thanks. you can rate this solution and show your appreciation.

Fan not working could be fan switch, fan, blower motor resistor, or wiring.

make sure nobs are not broke pull them off check for cracks if not the your blend door might be sticking

Are the electric fans coming on" Is the new radiator a double or single row?

hello, this sounds like a bad blower motor resistor!! its cheap and easy to change..if you need more info on locations let me know,, good luck.....marty

Pull out the blower motor and make sure the scroll cage (fan) is not loose on the motor shaft.