Abstract: A method of operating a switching relay with inductive coils by a microprocessor control to prevent the transient electro-magnetic noise caused by the switching relay from resetting the microprocessor and restarting the program at the beginning. Prior to switching a relay a code is loaded in the memory of the control. After the relay switching noise causes a reset, the control detects the code and jumps back to its proper place without a disruption in its operation.

Abstract: A method of operating an air conditioning system including a refrigeration circuit having a compressor and a thermostat for sensing heating and cooling needs together with an indoor fan is disclosed. The indoor fan operation is controlled based upon a microprocessor control remembering whether or not the unit was in continuous fan operation prior to the compressor operating to satisfy a heating or cooling need. Through the setting of a flag the microprocessor remembers the previous inputs such that operation of the fan may be controlled regardless of the condition of the compressor especially as concerns operation of the fan when the compressor is prevented from operating due to a safety, overload or timed off condition.

Abstract: Apparatus and a method for providing failsafe supplemental heat operation of an air conditioning control are disclosed. Operating power to a microprocessor control is discontinued when the air conditioning unit is placed in a supplemental heat mode by the user. The microprocessor control is so arranged that appropriate connections are made to operate a supplemental heat source in response to a first stage heating need being sensed by the thermostat when operating power to the microprocessor control is discontinued. Under normal conditions multiple stage heating operation is provided with a supplemental heat source being operated under control of a programmed microprocessor.

Abstract: Method and apparatus are disclosed wherein a circuit for detecting the phase angle of a motor is disclosed. This circuit utilizes zero crossing detectors to compare the voltage and current signals such that a digital signal indicating the value of the phase angle by the duration of the signal is generated. Additionally, a method and apparatus for comparing the phase angle to the reference phase angle value is disclosed. Means for updating the reference value and for comparing the detected value to the reference value to determine appropriate defrost initiation time are additionally disclosed.

Abstract: An apparatus and method is disclosed for regulating delay periods in the operation of an air conditioning system. A speedup means is provided for a serviceman to speed up the delay intervals to avoid long waiting periods between modes of operation of the air conditioning unit. Means are provided for removing the speedup means after delay periods have occurred to prevent inadvertent operation of the air conditioning system with shortened delay intervals.

Abstract: A method of operating an air conditioning system including a refrigeration circuit having a compressor and a thermostat for sensing heating and cooling needs together with an indoor fan is disclosed. The indoor fan operation is controlled based upon a microprocessor control remembering whether or not the unit was in continuous fan operation prior to the compressor operating to satisfy a heating or cooling need. Through the setting of a flag the microprocessor remembers the previous inputs such that operation of the fan may be controlled regardless of the condition of the compressor especially as concerns operation of the fan when the compressor is prevented from operating due to a safety, overload or timed off condition.

Abstract: Apparatus and method for effecting self-test of a thermostat is disclosed. The permissible thermostat outputs are arranged into an array capable of being converted into a binary number. Testing is done to determine whether or not the binary number ascertained falls into a known legal array of binary numbers for permissible thermostat outputs. If the testing indicates a fault condition then the fault is indicated and operation may be discontinued.

Abstract: A method for controlling the energization of a crankcase heater for use in a refrigeration circuit is disclosed. The crankcase heater is energized through normally closed relay contacts except when the compressor is operating and except for a delay period after compressor operation. A microprocessor control is utilized to calculate the delay period based on the length of the period of compressor operation and to control the energization of the crankcase heater.

Abstract: An electrical system which is part of a control system for a heat pump is disclosed. In addition to other functions, the electrical system protects an AC power supply for the control system from a short circuit condition in an electrical load connected to the power supply. The electrical system includes a device for monitoring the voltage drop across the load and for generating an electrical clock signal only when the monitored voltage drop exceeds a selected level indicating no short circuit condition in the load, a microcomputer having an internal timer for receiving any generated clock signal, and relay means controlled by the microcomputer for operating switches to disconnect the AC power supply from the load when a short circuit condition is detected in the load.

Abstract: A method and apparatus for recording and translating data using sequential spacing of data points on a recording medium. Electrical pulses are generated in response to the quantitative level of a series of events to be monitored. These pulses are then applied sequentially from a base reference point to the recording medium. The pulses are applied so that the distance between pulses is indicative of the quantitative level of each monitored event. This method is particularly useful in field instrumentation for monitoring equipment performance, process variables, weather conditions and any other variable events or conditions. Any number of events may be periodically sequentially applied to the medium over a long period of time. The recording medium can then be played back at high speed to translate the information obtained.