when the defroster is turned on, it activates the a/c compressor. the clutch may be locking up on the compressor.
a bad pulley or misaligned driven component. If one of the pulleys in the system is tilted it will drive the belt off in that direction. the belt has stretched and needs replacing
To keep tension on the belt so as not to slip.
tighten belt or replace it if it is glazed on contact surfaces
Release the tension with a 14 mm combination wrench slip it off with your other hand. If you got big arms then remove the passenger wheel and go from the bottom; much easier.
If you are talking about slip in a conveyor belt connected to a motor, the answer is there will not be any effect on the motor, but the slip will cause the efficiency of the connected device.
Could cause the belt to slip and the engine to overheat.
Less surface contact with belt.
Yes
To prevent objects being conveyed on the belt from sliding around on the surface of the belt.
Pull back the belt tensioner and slip the belt off. Reverse procedure to install.
Worn belt or belt that has stretched to the point the tensioner cannot keep the proper tension. The tensioner can also be defective. Replace the belt and the tensioner.
There is a central pulley that is spring loaded. There is a bolt on the end of it but you don't want to remove the bolt. You need to put a wrench on the bolt and take pressure off the belt with one hand and slip off the belt with the other. Try to remember the travel pattern for applying the new one. If you forget, there should be a picture of it somewhere inside the engine compartment.