Abstract: A compact alarm system is provided by a temperature sensing switch within a refrigeration unit, the temperature of which actuates the switch when temperature rises to a predetermined level. Change of condition of the contacts induces a pulse which triggers an integrated circuit timer. The timer imposes a predetermined delay before activating a communications linkage. No permanent wiring and, at most, only light wiring is required in the location of the refrigeration unit and wiring may be eliminated entirely by employing individual transmitters in each case. Remote alarm means provides a predetermined alarm indicating abnormal conditions in the refrigeration unit, preferably in response to a radio signal transmitted from the location proximate to the refrigeration unit. The receiver activates an automatic telephone dialer which dials pre-programmed telephone number and plays a pre-recorded message.