An apparatus for calibration and testing of pressure switches which are used in residential and commercial HVAC systems. The apparatus can be used to test, set, or adjust a pressure switch or a pressure signal transducer to the manufacturer's specifications. The apparatus includes an exterior housing with an on/off switch and at least one vacuum inlet nozzle, and the inside of the housing includes an air compressor to which the amount of voltage supplied can be manually controlled. The air compressor typically operates from a battery power supply located within the housing. A pressure measuring device, such as a differential pressure gage, and a conductivity indicator are typically used in conjunction with the device to calibrate adjustable pressure switches and to test and diagnose faulty pressure switches. The apparatus can include the pressure measuring device and/or the conductivity indicator within its housing.

A multi-mode air compressor pressure switch is disclosed. A first mode of operation of the switch has a first range that includes a first cut-out pressure and a first cut-in pressure. A second mode of operation of the switch has a second range that includes a second cut-out pressure and a second cut-in pressure. The second range is smaller than the first range. The second mode of operation adds compressor output over the first mode of operation to extend operable time of a tool that is connected to a compressor that is controlled by the first mode and the second mode.

An apparatus for calibration and testing of pressure switches which are used in residential and commercial HVAC systems. The apparatus can be used to test, set, or adjust a pressure switch or a pressure signal transducer to the manufacturer's specifications. The apparatus includes an exterior housing with an on/off switch and at least one vacuum inlet nozzle, and the inside of the housing includes an air compressor to which the amount of voltage supplied can be manually controlled. The air compressor typically operates from a battery power supply located within the housing. A pressure measuring device, such as a differential pressure gage, and a conductivity indicator are typically used in conjunction with the device to calibrate adjustable pressure switches and to test and diagnose faulty pressure switches. The apparatus can include the pressure measuring device and/or the conductivity indicator within its housing.

A multi-mode air compressor pressure switch is disclosed. A first mode of operation of the switch has a first range that includes a first cut-out pressure and a first cut-in pressure. A second mode of operation of the switch has a second range that includes a second cut-out pressure and a second cut-in pressure. The second range is smaller than the first range. The second mode of operation adds compressor output over the first mode of operation to extend operable time of a tool that is connected to a compressor that is controlled by the first mode and the second mode.

An apparatus for calibration and testing of pressure switches which are used in residential and commercial HVAC systems. The apparatus can be used to test, set, or adjust a pressure switch or a pressure signal transducer to the manufacturer's specifications. The apparatus includes an exterior housing with an on/off switch and at least one vacuum inlet nozzle, and the inside of the housing includes an air compressor to which the amount of voltage supplied can be manually controlled. The air compressor typically operates from a battery power supply located within the housing. A pressure measuring device, such as a differential pressure gage, and a conductivity indicator are typically used in conjunction with the device to calibrate adjustable pressure switches and to test and diagnose faulty pressure switches. The apparatus can include the pressure measuring device and/or the conductivity indicator within its housing.

A diagnostic by-pass apparatus electrically connectable to a pressure switch, a roll-out switch, and a limit switch of a furnace is disclosed. Each switch has two electrical leads. The apparatus includes a housing, an enclosure in the housing, an electrical circuit in the enclosure, and a continuity indicator electrically connected to the circuit and electrically connectable to both leads of each switch, one at a time. The indicator is used to identify a defective switch when the by-pass apparatus is connected to both leads of the switch.