Control Module HVAC: Description and Operation
Communication and Programming With ECC Control Module
The air conditioning system's control module is connected to the diagnostic test point, and its diagnostics conform to the new diagnostics concept.
It is also possible to program the control module with certain functions by means of the Volvo System Tester via the diagnostic test point.
The control module can identify 38 different faults and hold 10 faults in memory.
The control module also has in-built emergency programs for most types of faults.
Error Indication
If a fault develops on the air conditioning system the orange-colored light-emitting diodes for the A/C and recirculation flash for 20 seconds to warn the driver. The diodes also flash for 20 seconds every time the ignition is turned on, and/or when the engine starts.
If the fault is intermittent there is no flashing when the fault is not present. Faults on the sun sensor give no error indication.
Self-Adjustment
If the damper motors on a new control module have not been self-adjusted, or if programming has changed the green light-emitting diode for the A/C will flash.
Self-adjustment can be activated in 2 ways:
- Via the diagnostic test point, by means of the Volvo System Tester.
- Driving the car above 30 km/hr (19 mph) for at least 15 seconds and charging the generator (D+ signal high).
NOTE: It the green A/C diode is not flashing self-adjustment can only be carried out using the Volvo System Tester.
During self-adjustment the green light-emitting diode for the A/C flashes.
If self-adjustment fails an error code is stored in the control module, and the orange diodes give an error indication.
The control module automatically checks the following components following self-adjustment:
- Normal function of the fan.
- The readings from the sensor and control signals are within acceptable limits.
Reading Error Codes; Erasing Error Codes
The Volvo System Tester is used to read error codes, counters, rolling values and to erase error codes, via diagnostic test point.
The control module can be programmed for different chassis and equipment, allowing one and the same control module to be used for all cars. This means that if the control module is replaced it must be adjusted for the car in order to function normally.
Programming is carried out via the diagnostic test point using the Volvo System Tester.
The control module can be programmed with the following parameters:
- If the car is left or right-hand drive.
- Type of engine, petrol or diesel.
- If the air conditioning system's air intake has a dust filter.
- Adjustment for the temperature inside the car in relation to the temperature controls.
- Adjustment for the blower motor speed in relation to the position of the fan controls.
NOTE: A new control module must always be programmed for left or right-hand drive before it will work. Damper motors, etc cannot be self-adjusted until programming is complete.
If a used control module is fitted programming for left or right-hand drive must be checked to ensure that it corresponds to the car
New control modules are set up for petrol engines with no dust filter. Re-program these parameters if they do not correspond to those of the car into which it is being fitted.
Before the control module is programmed the two green indicating diodes will flash. If the A/C is off and recirculation is selected the indicating diodes remain lit.