A temperature controlled cabinet system and method enables medical items associated with particular temperature ranges to be stored and maintained within the associated temperature ranges in cabinets disposed within ambulances and other medical vehicles. The system includes a temperature sensor for measuring the cabinet interior temperature, a controller assembly for controlling system operation and two head pumps disposed in the cabinet walls to heat or cool the cabinet interior. Alternatively, a single head pump may be utilized to heat or cool the cabinet interior. The controller assembly includes a control console for displaying the actual cabinet temperature and entering a desired temperature range into the system. The heat pumps include a pair of heat sinks disposed about a thermoelectric device (e.g., a Peltier chip) that heats one heat sink, while cooling the other heat sink based on voltage polarity or current flow direction applied to the device. The system controls voltage polarity applied to the thermoelectric device to enable the heat pumps to heat or cool the cabinet interior in response to a comparison of the measured temperature with the desired temperature range. The system utilizes D.C. power from the vehicle electrical system, and may be installed in new cabinets or retrofit into previously disposed cabinets lacking temperature control capability.