What do you do if your air conditioner breaks down during a heat wave? Please be careful and take the situation seriously. Heat can kill, especially the very old, very young, and those who have serious medical conditions. We should all remember to check on those most at risk. There are some steps you can take to survive until the heat passes or the AC comes back on. These include making sure the air-conditioner is set properly, keeping as cool as possible, and even rigging up a temporary home-made evaporative cooler. Perhaps the first thing to do would be to call your local air conditioning expert and arrange an emergency visit. In a heat wave, you will not be the only one calling, so call early. Then you should take steps to keep your cool until help in the form of an air conditioner repair technician arrives.