Abstract: A compressor heating system includes a compressor drive controller electrically coupled to an outdoor controller configured to selectively implement a pulse width modulation algorithm to deliver a pulsed direct current (DC) from the compressor drive controller to at least one stator winding of a motor of a variable speed compressor to provide heat to the compressor to prevent refrigerant migration to the compressor when the compressor remains idle with respect to operating in a cooling or heating mode.

Abstract: A compressor heating system may include a compressor drive controller electrically coupled to an outdoor controller configured to selectively implement a pulse width modulation algorithm to deliver a pulsed DC current from the compressor drive controller to at least one stator winding of a motor of a variable speed compressor to provide more efficient auxiliary heating to the compressor to prevent refrigerant migration to the compressor when the compressor remains idle with respect to operating in a cooling or heating mode. The compressor heating system may consume less off-cycle power than traditional compressor auxiliary heating systems, thus complying with regulatory requirements where off-cycle power must average below specific thresholds.

Abstract: The refrigerant charge adequacy of an air conditioning system is determined by the sensing of two temperatures in the system, one being at a midpoint in a condenser coil and the other being the temperature in the liquid line of the condenser discharge, with the difference then being indicative of the degree of subcooling, which, in turn, may be indicative of refrigerant charge condition. The method is refined by measuring a third temperature at the compressor discharge, with the three temperature values then being used to calculate a pair of residual values which provide an indication of whether the two temperature approach is useful in determining charge adequacy under the existing conditions and if not, whether the system is overcharged or undercharged.

Abstract: The sufficiency of refrigerant charge in an air conditioning system is determined by a comparison of two sensed temperatures in the system, one being the liquid line temperature and the other being either the outdoor temperature or the condenser coil temperature. In one embodiment the two sensed temperatures are displayed on respective thermochromic strips which are so calibrated and juxtaposed as to provide a visual indication, by the relative positions of the two displayed sensed temperatures, as to whether the refrigerant charge is adequate. In another embodiment, the sensed liquid line temperature is displayed by way of a plurality of LEDs and the other temperature is displayed by way of a marker on a temperature scale. If the two displayed temperatures are aligned, then the refrigerant charge is optimized, and if they are not aligned, the system is undercharged or overcharged.

Abstract: A braze-free connector for attaching a flow line to an operating unit of a flow system. The connector has a central passage into which the flow line is inserted through a tapered entranceway. The entranceway opens into a radially expanded cavity that surrounds a section of the flow line. The cavity is filled with a pressure activated adhesive. A ferrule is mounted in the entranceway and is rotatably mounted upon a threaded nut which mates with a male thread on the connector body. As the nut is advanced, the ferrule moves axially into the cavity to activate the adhesive, and at the same time, is forced radially into tight sealing contact with the flow line.