We've owned our home for 6 years now and I have tried to maintain the AC unit (outside, central air unit, don't know the brand... no tags or stickers) every fall and spring and have checked everything before starting the unit in summer. This year it ran for the first few days, then a few days later when the fan in the furnace turned on to start blowing air, the AC unit didn't fire up. I've checked all of the electrical connections incase any critters chewed a wire or something came loose, and everything was fine. We have never had to top up the coolant, but I was under the impression that the unit would still start even if it was low or out of coolant. Is this not the case? Will the AC unit not start without/low coolant? Any suggestions would be appreciated. Thanks.

Have 15-year-old York a/c and wont blow cool air through inside vents. Outside line is wet and cool. Had main breaker trip this afternoon. Since then, no cool air. Fan on unit blows cool outside. Thermostat seems to be working OK. Recently, contact relay malfunctioning--A/C would not shut off unless switched at breaker, but would cool OK. Any help would be appreciated---NC July no fun without AC.