Abstract: An alarm system which is particularly adaptable for deterring theft of condenser coils from the outside condenser unit of a home or business air conditioning system. The alarm system of the present invention includes an alarm monitor circuit which is connected to the condenser coils or to an alarm panel or screen on the housing of the condenser unit, typically using a tethered switch, an alarm clip, magnets, or other suitable attachment mechanism. The alarm monitor circuit is broken and activates an alarm upon partial or complete removal of the condenser coils or upon partial or complete removal of the panel or screen from the condenser unit.