There is described a HVAC pre-filter system for a vehicle. The pre-filter system acts to prevent relatively large or coarse debris from reaching a dedicated HVAC filter through the use of at least one pre-filter element, which is provided in at least one inlet/outlet connected to ambient air. The pre-filter system has an inlet to supply air to the HVAC system, and an outlet to allow for air to exit from a vehicle cab interior, and the inlet/outlet can be switched to be fluidly coupled with either the HVAC inlet or the cab outlet. Dependent on which inlet or outlet the inlet/outlet is coupled with, the flow direction in the inlet/outlet can be controlled. Accordingly, the pre-filter can be cleaned of accumulated dust and debris by reversing the direction of airflow through the inlet/outlet.