If your furnace is blowing cold, that is usually a sign that there is an issue with your furnace. A few simple checks to make before calling in for service. Check the breakers to the furnace. Sometimes breakers tend to trip when there is a further issue going on and other times they can trip during a storm or other reasons that just require a reset. Check your air filter. Air filters can cause your furnace to lock out due to safety reasons. If your filter was dirty, replace it, and cycle power to your furnace. If both suggestions didn’t help, call your AC & Heating Experts for service! We are more than happy to help.