First, treat this as two separate problems while troubleshooting.  Turn the
A/C on and lift the hood and see if the compressor is turning or not, when
you expect it should be.  Essentially you could have three basic problems
with the A/C .. low refrigerant, electrical or a damper door problem in the
HVAC box.  Try to figure out exactly which of these is your problem.

The wiper problem would likely be electrical in nature.  If there is a
problem that relates the two "symptoms" then I would vote that it is
electrical.  Therefor it would have to be something in common such as a bad
ground connection that they share .. or a loose hot wire .. either will
cause intermittent operation.

One way to determine a loose connection is to wiggle wires in the
neighborhood of the controls under the dash or under the hood to see if you
can make the problem come and go.  Get a copy of the electrical schematics
for the car and find wires that the two systems share, if any and hunt them
down and inspect their connections for breaks or corrosion etc.