1. We prepare the car for work («Preparing the car for maintenance and repair»).
2. We start the engine.
3. Turn the knob of the air temperature regulator counterclockwise to the extreme position (blue sector).
4. Using the heater fan control knob, turn on the four speeds of the electric fan in turn. By the intensity of the air flow from the nozzles, we check the operation of the electric fan and the change in the speed of rotation of its impeller when changing modes (1 is the minimum speed and 4 is the maximum). If the electric fan does not work in all modes, check the additional resistor («Additional resistor - check and replace») and switch. If the electric fan does not work, then check the power supply circuit of the electric fan («Checking the technical condition of electrical equipment»).
5. Turn on the maximum speed of the electric fan.
6. By turning the control knobs for the heater dampers and ventilation grilles, we monitor the change in the direction of air flows. If there is no change in flow distribution, the damper actuator is most likely defective.
7. Warming up the engine to operating temperature, turn the knob of the air temperature regulator clockwise to the extreme position (red sector).
8. We make sure that the air leaving the panel nozzles has become warm. If the air temperature has not changed, the central damper actuator may be faulty.
9. Turn the temperature control knob to the blue sector - cold air should go into the cabin. If the temperature does not drop, then the central damper actuator is faulty.