A: The pressure cycling switch controls the refrigeration cycle by sensing low-side pressure as an indicator of evaporator temperature. To remove the switch, disconnect the negative battery cable, unplug the electrical connector, and remove the switch and O-ring seal. To begin the installation, begin by putting in a new O-ring, lubricating it with refrigerant oil, and installing the switch. Engage the electrical connector, and connect the negative battery cable. Reset the radio, clock, and any other applicable electronic devices.