Houston Air Conditioning Guide: Causes of AC Short Cycling

Air conditioning short cycling is a common problem wherein an air conditioning unit will have either short run times or short off times.  This type of quick movement back and forth between being on and off–or rather starting and stopping rapidly–can be detrimental to the overall life of your Houston AC unit, and is also not energy efficient.

AC short cycling can have many causes, and many fixes.  Below are the main causes for air conditioning short cycling, which can be checked, diagnosed, and fixed quite easily.

  • AC Refrigerant Leak:  There could be a refrigerant leak somewhere within the AC unit.  A temporary fix might be to add refrigerant and recharge the air conditioning unit, but long-term, a Houston HVAC specialist will need to be contacted in order to find and fix the leak properly, ensuring excess money is not paid to continually add an unnecessary amount of refrigerant.
  • AC Coil Icing: This means that the evaporator coil or cooling coil has become encrusted with ice or frost and is causing the unit to malfunction by turning on and off in short bursts.  Turning off the unit completely and letting the ice melt, then checking and replacing dirty filters can oftentimes fix this problem.
  • AC is Oversized:  The amount of power needed (or the BTUs needed) to cool a space is directly proportional to the size of the space or room which is being cooled.
    • If AC short cycling has been a constant problem since day one of an AC system installation, it is entirely possible that the A/C unit is too large for the space which it is cooling.  This could mean contacting an HVAC technician to have the unit analyzed and a new, smaller unit put in.
    • If A/C short cycling is a relatively new problem, some possible causes could be: closing or opening doors which previously were not closed or opened frequently, or the addition of partitions within rooms which effectively makes the room size smaller.  This could mean simply adjusting the thermostat, or the blower fan to a lower speed to compensate for the change, or opening interior doors to increase the size of the space which is being cooled by the AC unit.
  • AC Control Board Problem:  While less likely, the problem could be in a control board or control switch which has been damaged, thus causing erratic and rapid starting and stopping cycles.  In this case an HVAC technician would need to be contacted in order to replace the broken control switch.
  • AC Compressor Damage or Start-Up Issues:  Some AC systems have hard-starting compressors which take time to re-pressurize properly after shutting down.  If the AC system is being turned on or off manually on a frequent basis, the compressor might have a hard time restarting because the high pressure which had built up on the previous on-cycle had not had a chance to come down to normal levels again.  An easy way to diagnose this problem is if after leaving the AC unit shut off for thirty minutes, the unit works properly after being turned on again.  To help this compressor issue, an HVAC service technician can add a starter capacitor to the AC unit.

These and other AC short cycling causes can be checked, diagnosed, and fixed quite easily by an experienced HVAC professional, so call Air National if you need any AC repairs in the Houston area!

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