I have a heat pump system that was installed in 2006. I recently purchased the house. The filters were changed and checked prior to my purchase in March 2019. The system seems to be doing ghost runs at specific times each day, even if I move the thermostat to system setting 'off' there is no 'off' setting for the fan - it is on, auto, or circ only - I have it set on auto. the ghost times actually reset themselves when daylight savings time happened, so somewhere in the system, this thing believes it is supposed to run cool air from 9:40 to 10PM, from 10:10 to 10:30 PM and again at 4AM for an hour. I called the Rheem/Honeywell thermostat folks, and we completely rescheduled the set up and the 7 day schedule, however the odd times of running cool air continues. it is the same three times every day. If you can help me understand this problem and correct it; it will be much appreciated. The Thermostat is TH8320U1065 the outside fan is RPP8-048JZ model 7071-M0906-1134 The large unit in the garage is RHKA-HM4821JA - Thanks

  • disconnect the thermostat at 9:35PM and wait 10 minutes – jsotola Nov 18 '19 at 1:32
  • What is the thermostat calling for when these "ghost runs" happen? Heat? Cool? Fan? (you can check by measuring voltage between the C terminal and the Y, G, O/B, and W terminals at the air-handler/furnace unit, 24VAC is ON while close to 0VAC is OFF) – ThreePhaseEel Nov 18 '19 at 1:58
  • Is there a second thermostat? upstairs? – Rob Elliott Nov 18 '19 at 15:47
  • There is a specific feature that some people use that will circulate air in the home for a minimum amount of time each day. I've always seen it as a function of the thermostat, but it's possible something else is maintaining that schedule. As stated above, if you unhook the thermostat and it still happens, you need to look somewhere else. – JPhi1618 Nov 18 '19 at 16:15
  • Also is there a humidifier or other auxiliary equipment that could be causing the fan to run? – JPhi1618 Nov 18 '19 at 16:29

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