Contents: Checking the temperature sensor ↡ Checking the voltage supply to the…↡ Checking the regulator ↡
If there is a fault in the heating control system or in the double valve, the valve remains open. To determine the cause, it is necessary to check the heating control system devices one by one.
Sequence of works
"15,000 km annually"
1. Check fuse #5 (see "Electrical equipment").
2. Check double valve: Set the temperature control on the instrument panel to the "cold" position.
3. Remove the connector from the valve, connect the test lamp between the gray-red and brown-violet or brown-red wires.
4. Turn on the ignition.
5. If the control system is working properly, there is voltage in the circuit and the lamp will light.
6. Reverse check: turn the regulator to the "heating" position - the test lamp should go out.
Conclusion: If the voltage supply circuit is OK, but the fault in the heating system is not corrected, the cause is a faulty double valve (internal resistance 11-19 ohms). Replacement is necessary.
7. If there is no voltage in the circuit when checking, measure the voltage in the circuit between the supply wire (grey-red) and "mass" (for example, on the cylinder block).
8. Turn on the ignition. If there is no voltage, the current supply from the fuse is interrupted.
9. Checking the "mass" contact (from the control unit): connect a voltmeter between contact "30" and the brown-violet or brown-red wire of the contact connector. With the ignition on (regulator in the "cold" position), the device should show the battery voltage value. Otherwise, one of the elements of the heating control system is faulty (temperature sensor or control unit) or wire.
Checking the temperature sensor
10. First, you should remove the center console trim.
11. Connect an ohmmeter between both contacts of the right sensor, then the left sensor. The resistance values should be as follows at different temperature values:
- at an air temperature of +20°C - 10–13 Ohm.
- at a hand temperature of +30°C — about 8 Ohm. Otherwise, replace the sensor.
Checking the voltage supply to the control unit
12. Remove the regulator.
13. Connect a voltmeter to terminals "11" and "12" of the connector on the back of the regulator. With the ignition on, the device should show the battery voltage value. Otherwise, check the supply circuit, including the fuse.
Checking the regulator
14. It is impossible to check the regulator's serviceability on your own. The authors proceed from the following: if the voltage supply, valve and temperature sensor are in order, the cause of the regulation system malfunction is in the control unit.