• Detects errors in the input and output signals. (The ignition switch is at the ON position or the engine is running.)

• If a malfunction is detected, a DTC is output to the DLC-2 through the malfunction display function. At the same time, malfunction detection results are sent to the fail-safe and memory functions.

• If a malfunction is detected by the malfunction detection function and a malfunction is determined, the following controls are performed to prevent an operating malfunction of the full-auto air conditioner and malfunction of output parts.

• Due to factors such as direct and intermittent sunlight (travelling through a city or highway tunnel), or radiant heat from the ground under a parked vehicle as well as the opening and closing of doors, the amount of solar radiation, and the ambient and cabin temperatures may change intermittently, partially, or suddenly. If control was performed based exactly on these variations, the air conditioning function would be negatively effected and smooth control could not occur. In order to prevent this, the climate control unit delays the input signals for solar radiation, and the ambient and cabin temperature as shown in the following figure. Stable control occurs due to the reading out of an average of all the variations.

• When the engine is re-started after being temporarily stopped, the ambient temperature sensor may detect a temperature higher then the actual ambient temperature. To prevent this, when the engine coolant temperature exceeds the specified value, the detected ambient temperature is corrected based on the data for the ambient temperature before the engine was stopped that is stored in climate control unit and control is performed accordingly.

• Stores the signal determined to be malfunctioning by the malfunction detection function, and the memory is not cleared even if the ignition switch is turned off (LOCK position) or the malfunction has been repaired.

• Clear stored malfunction data by connecting the Mazda Modular Diagnostic System (M-MDS) to the DLC-2.

• This function is for outputting present or past malfunctions via the DLC-2 as DTCs.

• DTCs output via the DLC-2 can be read out using the Mazda Modular Diagnostic System (M-MDS).

• Present and past malfunctions in the control system circuits (open/short circuits) are detected, and the DTCs indicated in the table are displayed on the Mazda Modular Diagnostic System (M-MDS). Since once a past malfunction is stored, it will remain stored even after the malfunction has been repaired, clear past malfunctions after completing repairs.

• Clear stored past malfunctions by connecting the Mazda Modular Diagnostic System (M-MDS) to the DLC-2.

• The PID/data monitor function is used for optionally selecting input signal monitor items preset in the climate control unit/water heater unit and reading them out in real-time.

• The simulation function is used for optionally selecting simulation items of output parts preset in the climate control unit and to operate them regardless of the climate control unit.

• The climate control unit forces operation of output related moving parts as indicated in the operation check table regardless of input related parts, while simultaneously changing the display on the information display as well as illuminating each switch indicator light automatically. A malfunctioning part can be determined by verifying that each transition is as indicated in the operation check table through visual inspection, listening to the operation sound, or placing a hand on the air vent.