Light on dash of 94 sentra does not come on and a/c does not work

I'd check the battery to make sure that it is fresh (newer than five years old) next I'd take my NEW battery and would connect it to a couple of cleaned off of corrosion with a wirebrush cable clamps...next I'd take the big 1/0 cable end and wirebrush that one too, and the place where the chassis/ground is connected to the unibody/frame....bolt it back up to assure that 300 cold-cranking amps can get through there...next be sure that fat ole' cable goes to the "frame" and engine block too---the alternator bracket is a typical place for this to be connected...on the red terminal make sure the battery cable to the starter solenoid has no corrosion as well as the little lollipop connector at the battery (return from the alternator and/or accessories connector) should be able to push a few amps through there without corrosion....all in all have an electrically sound connection to the battery...grounding to the chassis, then we will take inventory on what works and what doesn't~

the spot where the ground cable connects is the most critical element of this repair~ take it down to shiny metal (no paint or corrosion) for this most important connection to be sure the instrument panel gets the grounding that it desperately needs~

I'd go for the obvious and verify the fuses first. If it's not that, Roy's answer seems pretty complete. Good luck with your repair!

It's kind of a bust that things that work just fine, given a couple of years will turn out crappy (and I'm not talkin' about marriage here) subject to the elements...today I read in two places about Benzene bein' such a baddy and attacks the human body depositing itself in the bones and all kinda scary stuff, but your body knows to stay the hell away from things that harm...at least my senses do~