Turn on the ignition.
Check the voltage supply to the device: disconnect the plug connector, connect a semiconductor test lamp between the plug and the positive (+) pole of the battery, the LED should light up. Otherwise, replace the air damper control device.
Connect the plug connector.
Slowly press the gas pedal and start the engine. Air damper (carburetor upper flap) must be closed.
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Leave the engine running at idle speed. Depending on the ambient temperature, the air damper should open fully after about 5 minutes. Otherwise, check the device's thermal switch.
Turn off the engine.
Checking the thermal switch of the automatic device for enriching the combustible mixture at start-up
Disconnect the thermal switch plug. The thermal switch can be identified by the green insulation, it is located on the cylinder head near the intake manifold, see above.
Connect an ohmmeter to the contacts of the thermal switch. At a coolant temperature above +55°C, the electrical circuit of the thermal switch should be closed. The prescribed resistance value is 0 Ohm.
Allow the engine to cool down to a coolant temperature below +16°C. If the ambient temperature is above +16°C, remove the thermal switch and cool it in a water bath. Measure the resistance again, the prescribed value is ∞ (infinity) Ohm.
If the measured values do not correspond to the specified values, replace the thermal switch.
If no fault is found, remove the air damper control device and check whether its bimetallic plate is broken.
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