Contents: Checking the electromagnetic clutch…↓ Checking the compressor on the car ↓ Checking the heater resistor ↓ Checking the heater fan transistor ↓ Checking the cabin temperature sensor ↓ Checking the ambient air temperature…↓ Checking the temperature sensor…↓ Checking the light sensor ↓ Checking pressure switches ↓ Checking switches by coolant…↓
Checking the electromagnetic clutch on a car
1. Visual inspection.
a) Check that there are no traces of oil on the pressure plate and rotor.
b) Check for noise and grease leaks at the clutch bearings.
2. Check for extraneous noise from the clutch bearings.
a) Start the engine.
b) Check for any extraneous noise from the clutch bearings when the air conditioner is off.
If there is extraneous noise, replace the electromagnetic clutch.
3. Checking the electromagnetic clutch.
a) Disconnect the connector from the electromagnetic clutch.
b) Connect the positive battery terminal to the clutch connector terminal (see picture), negative terminal to ground.
c) Check the operation of the clutch. Replace the electromagnetic clutch if it does not operate.
Checking the compressor on the car
Measure the resistance between terminals "1" and "2".
Nominal resistance - 185 Ohm at 20°C
Checking the heater resistor
Measure the resistance between the terminals.
- Resistance - 2.6 Ohm
Checking the heater fan transistor
1. Measure the resistance between the terminals.
Nominal resistance:
- between terminals "2" and "1" - 2.2 kOhm
- between terminals "3" and "4" - 1.92 kOhm
2. Checking the work.
a) Connect the "+" of the battery to terminal "2", through a 12V, 3.4W test lamp to terminal "3".
b) After that, connect "+" to "4", make sure that the lamp is on.
Note: The test must be carried out within a short time.
Checking the cabin temperature sensor
Check the compliance of the sensor resistance dependence on temperature (see picture).
- Resistance at 25°C - 1.6-1.8 kOhm
Checking the ambient air temperature sensor
The check of the interior temperature sensor is similar.
Checking the temperature sensor behind the evaporator
Resistance:
- at 0°C - 4.6-5.1 kOhm
- at 15°C - 2.1 -2.6 kOhm
Checking the light sensor
1. Cover the sensor from light and check that there is no conductivity between the terminals.
2. Direct a bright light source at the sensor and check for conductivity.
Checking pressure switches
Check that the pressure switches are working.
Checking switches by coolant temperature
Place the bottom of the sensor in water, check the conductivity between the body and the terminal when the temperature changes.
Sensor #1
- a) Conductivity exists at temperatures of 90°C and above.
- b) There is no conductivity at temperatures of 83°C and below.
Sensor #2
- a) Conductivity exists at temperatures of 100°C and above.
- b) There is no conductivity at temperatures of 95°C and below.