Check the operation of the meter (see instructions for use of the device).
Set the unit to°C.
Set the reading sensitivity to 0.1°C.
Set measurement mode (AT) = (T1-T2).
Check the two sensors T1 and T2 by determining the correction (A) in mode (ΔT) = (T1-T2). The two sensors should show the same values under the same conditions.
Perform checks:
- by setting the sensitive elements of the sensors so that they are in contact;
- placing them in the air flow from the fan;
- by setting the fan speed in the cabin to the maximum value;
- wait for the readings to stabilize;
- determine the amount of correction (Δ).
Determine the difference and its sign after the temperature has stabilized.
Determine the correction (Δ) = - (T1-T2) for measuring (ΔT).
Examples:
- If (T1-T2) = -0.3°C, correct measurement (ΔT), by introducing the correction (Δ) = +0.3°С;
- If (T1-T2) = +0.3°C, correct measurement (ΔT), by introducing the correction (Δ) = -0.3°C.
Park the car in a room with a constant temperature of at least 15°C.
Close the hood.
Lower the windows of the front doors. Start the engine at idle.
Set the climate control controls to the following positions:
- air recirculation mode to the outside air intake position;
- air distribution at head level;
- air temperature switch to the position corresponding to the minimum temperature of the air supplied to the front (and in the back, if the system is installed there) part of the salon;
- the fan speed in the car interior is set to the maximum value (disable rear control panel if installed);
- the center and side vents on the front panel are open and set to the neutral position;
- the air conditioning system must be turned on (indicator is on).
Wait 5 minutes with the engine idling before taking measurements.
Record the temperature on the grille of the air intake niche (T3).
Depending on the vehicle model, open the hood to access the air intake grille.
Install the sensor in the place where the air enters the grille of the air intake niche.
Wait for the readings to stabilize. Register the temperature value of the TK.
Close the hood if it was open.
Record the temperature at the left side vent (T1) and temperature at the right side ventilation nozzle (T2).
Install the T1 sensor in the left side vent (1).
Install the T2 sensor in the right side vent (2).
After stabilization of the value (ΔT) define the temperature difference:
- between T3 and the highest of T1 or T2, (T3 - the highest value);
- determine this temperature difference;
- between T1 and T2 (clear the value (ΔT) in read mode (T1-T2));
- determine the temperature difference (ΔT) in relation to correction (Δ), to be taken during the measurement.
If the value (ΔT) = (T1-T2) unstable, perform the operations described below.
Note. 3 Depending on the programming of the air conditioning system, the test method may not be applicable due to the operation of the engine cooling fan. The operation of the engine cooling fan causes the temperature difference to be unstable (ΔT) for T1 and T2. To obtain correct measurement results, the cooling fan must be turned on during the entire time of measuring temperatures T1 and T2.
Keep the engine cooling fan running at all times by changing the engine speed.
Set the engine speed to 2000 rpm for the entire duration of the measurement of temperatures T1 and T2.
Make sure the engine cooling fan is turned on.
Record the temperature according to the instructions given in earlier.
The following two conditions must be met:
- the temperature difference between T3 and the largest of T1 or T2 must be greater than or equal to 5°C;
- the temperature difference between T1 and T2 must be less than or equal to 2°C.
If one of the two conditions is not met, the air conditioning system is defective. In this case, the air conditioning system of the serviced vehicle should be diagnosed.