• Won't quit running and should ductwork be checked?


    I have a 13 SEER unit that I bought 2 years ago. It is a Carrier brand. I set my thermostat at 85 when I was at work and when I came home my air conditioning unit was running. I cut it off and waited for about 5 to 10 minutes. My AC was still running. I put the clicker on “off” and it was still running so I clicked it to “heat.” The furnace came on, then back to off, then it finally turned off. What is wrong with my unit or thermostat? Also, my electric bill seems high. Should I have my ductwork checked?

    Some air conditioning systems will continue to “run” for several minutes after the thermostat is satisfied or even turned off.  The only part that should continue to “run” is the indoor fan system.  Among the possible causes of this problem are a faulty thermostat, a short between the R and the W terminal (R and W are your thermostat wires) that is keeping the heat on, or a stuck relay or sequencer in the furnace. Since there are a host of potential issues, the best course is to contact a professional HVAC contractor if the outdoor section is continuing to run. 

    Air duct cleaning should be considered if the home is 12 years or older. Even then the ductwork may not need to be cleaned if the equipment has been well maintained and the air filters have been changed or cleaned. If you remove a few supply air registers around your house you can see how dirty they are. There are some types of ductwork that can be damaged by cleaning. Perhaps you could have a duct cleaning camera the ductwork before deciding to have them cleaned.