Lennox

[nodcay]

Just an overview-- I have four new Lennox heat pump/AC units in a house that had a major remodel. Two of the units work fine (heat or cool), however, the other two will heat, but not engage the compressor when the thermostat is put on "cool." I have 240 volts to the connections at the units that do not kick on. Am not at home and will provide the thermostat manufacturer and model number of the Lennox units if it will help. Is this likely a thermostat problem? All breakers are on at the blower units in the attic. Blower fan starts up fine, but the compressors don't come on. All units have the same thermostat. Would it be worth trying to switch them to see if they work on the non-operating units? Thanks.

[Ron]

nodcay,  with the heat pump,  the compressor should be running in both the heat and cool mode.  Sounds to me like it is a wiring issue with the thermostat. Check the wiring on the units that work and make sure the others are wired the same.  Being that they are new units,  check all the wiring and make sure none of the wire nuts dropped off...Ron