Is it hot where you live and is your air-conditioning system not working? Here are a few things to check first before calling a repairman. No. 1 on the Carey Brothers' "no-go" checklist is to check your thermostat. Perhaps somebody changed the temperature setting or, if it's programmable, make sure the "on-off" settings are still correct. If things are OK here, check the power. See if the circuit-breaker has been tripped or turned off. If you have a fuse box, check to see if a fuse has blown. If power's OK, look for a cut-off switch (located right on the air conditioner). See if someone or something knocked it into the "off" position. If everything checks out, and it's still "no-go," it's probably time to call your repairman. If you do get it running, but no cool air comes out, perhaps the filter's clogged and needs changing. And that's the On The House tip for today.