My brakes grab on my 2000 jeep cherokee classic.

clicking could be a failing abs

Should be a 15amp fuse marked #23.
check your owners manual for details

around 30 to 60 dollars depending on what quality break pad you want or the longer you want them to last.

If you have rear drum brakes then a brake shoe could have come apart causing the wheel to grab and skid on the pavement. If you can see external signs of dark wet areas that would be a leaking brake cylinder which can also cause the brakes to grab. The other possibiity, more common with disc brakes, is that a brake calliper is closing, but is not releasing properly when you let off the brake pedal. This would require replacement of the disc caliper on the wheel where it is grabbing.
Warped rotors can also cause the brake to "grab" when you don't want them to, but generally it will grab and release with a "pulsating' feeling if that's the problem.

TO REPLACE SPARK PLUGS YOU REMOVE COIL PACK MOUNTING BOLTS THEN REMOVE THE COIL PACK WITH BOOT OVER THE SPARK PLUG.YOU HAVE 6 INDIVIDUAL COIL PACK TO EACH CYLINDER. YOU NEED A 3/8 RATCHET WRENCH - LONG 3/8 EXTENSION -SPARK PLUG SOCKET - SPARK PLUG GAUGE.AND TORQUE WRENCH.THE 2000 MODEL JEEPS FUEL FILTER INSIDE THE TANK.1993 - 1996 MODEL JEEPS FUEL FILTER LOCATED LEFT SIDE OF THE VECHICLE NEAR THE FUEL TANK.

Here you can find all teh section about 2000 Jeep XJ Cherokee Service Manual, check the Wiring Diagrams section, for fuses description and location.

Hope helps (remember rated this).

could be the brake switch went out of it

The brake light switch is defective or out of adjustment. More than likely located on the brake pedal arm near the top.

a/c not working/blowing 2000 jeep cherokee classic

this vehicle has three sensors two front and one on the rear end this sounds like most of your problems but have all your brakes checked .thank for your question