Easy step by step guide one how to troubleshoot and repair vent low air flow,
this article pertains to most vehicles.
Difficulty Scale: 3 of 10
- Most air control vents are equipped with
a flow control door that is located at the vent outlet. This door is controlled
by a thumb wheel that when activated will open and close the vent air flow door.
Work the thumb wheel from one side to the other while checking the airflow. The
flow should stop and start again, if the thumb wheel does not make a difference
the problem is somewhere else.
- Most cars are equipped with a cabin air
filter or hepa filter. These filters are designed to clean the air before it exits
the air vent. If this filter becomes clogged due to lack maintenance it will stop
or slow the flow of air exiting the vents. To check this filter locate the filter
housing which can be either under the dash on the passenger side or under the hood
of the car, near the base of the windshield on the passenger side,
the cabin air filter
Step 3 - A fan blower motor is controlled by either
a switch in the passenger compartment or by a computer. If this fan motor is starting
to fail it will cause the fan motor to run at a lower speed resulting in low air
flow. To test this condition an amp meter is needed, connect the meter lead to the
power wire of the fan motor. With the fan motor on in the full speed setting the
amp meter should read between 8 and 15 amps. Anything lower than 8 amps could mean
the fan motor has shorted and is not operating at full output.
Removing Air Cabin Filter
Step 4 - There are two air intakes for the ventilation
system, one fresh air the other is re-circulated air. If these air intakes become
plugged by a piece of paper, cloth or other form of blockage it will slow or stop
the airflow. Inspect both external and internal air intakes located at the base
of the windshield (external) and at the passenger side foot well (internal).
Article first published 2016-02-05