Mazda 5 Technical Guide HVAC



  1. Includes the on-board diagnostic function and A/C operation check mode. The on-board diagnostic function consists of a malfunction detection function that detects malfunctions in input/output signals, a memory function that stores detected malfunctions, a fail-safe function that prevents an operating malfunction of output parts where a malfunction is detected, and a malfunction display function that displays detected malfunctions.
  2. The malfunction display function and output device operation function is accessed by connecting the WDS or equivalent to the DLC-2.

Malfunction detection function

  1. Detects errors in the input and output signals. (The ignition switch is at the ON position or the engine is running.)
  2. 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.

Fail-safe function
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.

Sensor Signal Delay Function 

  1. 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.
  2. 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 55 °C {131 °F}, 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.

Memory Function

  1. 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.
  2. Clear stored malfunction data by connecting the WDS or equivalent to the DLC-2.

Display Function

  1. This function is for outputting present or past malfunctions via the DLC-2 as DTCs.
  2. DTCs output via the DLC-2 can be read out using the WDS or equivalent.

Malfunction Display Mode
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 WDS or equivalent. Since once a past malfunction is stored, it will remain stored even after the malfunction has been repaired, clear past malfunctions after completing repairs.

Mazda 5 Technical Guide HVAC For Free

(0) Comments

Leave A Response

Your email address will not be published with your comments.

Reload Image