The relay socket has an open connection #87.  This connection can be used to activate a buzzer or some other type of audible alarm. This connection can also be connected to some OEM computers to record when the monitor’s red indicator light was triggered and how many times.  Check with your OEM to see if their vehicle computers have the ability to record accessory alarms. 

 When using this feature, the monitor’s red power wire must be wired so that it turns on only in the A/C position and not in the heat or defrost position.  By using the OEM’s A/C mode switch or A/C on/off switch to activate the monitor, this also becomes your monitor reset switch.  Whatever switch you use to power the monitor is its reset switch. You must insure when using this feature that the A/C does not come on in cold weather (below 25 degrees Fahrenheit) or you will get a red indicator light and alarms due to the low pressure trigger on the hi/low pressure switch.

 The #87 connection supplies a 24 volt or 12 volt power source (depending on the relay and power source supply) when the red monitor light is triggered.  The #87 connection will supply continuous voltage until the monitor is reset. The brown wire must be connected to the hot side of the thermostat or whatever wire you cut to interrupt the power to the compressor clutch.

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