Air con actuators

Using the VERUS Pro to aid air con maintenance

Published:  17 April, 2015

Over the last couple of decades, manufacturers of family, sports and luxury cars have pushed boundaries to improve occupant safety and comfort. Using many different forms of research and trials, car makers have given us a variety of innovations to enhance our driving experience while making vehicles safer for drivers and passengers.

One, possibly overlooked, tool that has evolved over many years is air conditioning, which now forms part of a vehicle's active safety system. Many cars now have air conditioning at the very least, or even climate control; systems that contain high and low pressure sides, compressors, condensers, evaporators and refrigerant, along with many more components.

Most of the vehicle comfort systems now have some form of diagnostic capabilities, be it codes only, codes and data, or actuators. Focusing on automatic air conditioning from a 2005 Mercedes-Benz E-Class (W211), I selected the actuators (Figure 1) so that I could find lists of them (Figure 2).

When automatic air conditioning is working correctly, all of the components listed as actuators will be commanded by the control module to perform a given task.

However, when a driver complains about the system not working as it should do, that is where diagnosing automatic air conditioning is a difficult task.

Using a diagnostic tool to actuate many of the components fitted in the system - like the blend motors, blower, hot and cold taps and other parts - is a must. These components are usually in very hard-to-reach places at the rear of the dashboard, making access incredibly difficult and sometimes impossible without having to remove many interior panels and trims.

Using the VERUS Pro can aid the technician who is running the actuator test - they may visibly or audibly note the component moving during the given actuation period.

While running such actuators on the VERUS Pro, it may not be possible to see or hear the actuation events, but one of the VERUS Pro's unique features is the ability to view the oscilloscope while using the scanner.

This will assist any technician in diagnosing the automatic air conditioning system, running the actuator and viewing the scope monitoring the signal wire to a given component. The signal wire could be a simple PWM (pulse width modulation) or LIN (local interconnecting network).

That said, before we rush in with the diagnostic tools, it is important to make sure that the basics have been checked first - such as ensuring that the mechanical system is good, visually inspecting the system, checking there is the correct amount of refrigerant and PAG oil, referring to technical data and using the air conditioning service station.

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