Page 222 - Foton Workshop Manual - Auman EST-M

DI - 168 Diagnosis - Diagnosis-fault diagnosis of electronic and electrical parts

System function description
1. Refrigeration control

a. Compressor control
In normal operation of engine, open the blower, press the switch button of air conditioner, the air condition
controller detects that the evaporator temperature is greater than 6 ℃ and issues a request signal for turning on
of air conditioning, if the pressure of high pressure line of air conditioning is normal, the engine ECU receives
the request signal for turning on of air conditioning and then the control compressor relay is turned off, the
control compressor runs, and the condenser fan runs at a low speed, when the high-pressure pipeline reaches a
certain value, the condenser fan runs at a high speed.
b. Compressor protection
When the evaporator temperature is below 2℃, the compressor stops running to prevent the evaporator from
frosting, when the evaporator temperature is higher than 6℃, the compressor returns to normal operation.

When the pressure of high pressure pipeline of air conditioning system is higher than 3.2MPa or lower than
0.16MPa, the compressor stops for protection. If the electromagnetic clutch of compressor is closed before
starting the engine, the compressor can be turned on again after the engine has been started for 3.5 seconds.
When the engine is in high-load condition (such as the throttle is opened too large, the speed is too high or the
coolant temperature is too high, etc.), the compressor stops running to ensure the output of engine.
2. Blower motor control

a. When the ignition switch is in the "ON" gear, rotate the blowing rate knob on the air condition controller,
and you can control the air volume of the fan by a certain percentage. When the knob indicates the leftmost
side, the air volume is the minimum; when the knob indicates the rightmost side, the air volume is the
maximum.
3. Colad and warm throttle control

a. Rotate the temperature control knob on air condition controller, the temperature control knob drives the
cold and warm throttle and control the actuator of cold and warm throttle to run, in order to achieve the
conversion between cold and warm throttle. When the cold throttle is opened, the warm throttle is closed, on
the contrary, when the warm throttle is opened, the cold throttle is closed.
4. Mode throttle control

a. The blowing mode regulation function of air conditioning system can be converted amonmg six modes, the
parallel air outlet (blowing face), the double planes (blowing face and feet), the bottom air outlet (blowing
feet), the bottom air outlet (large) and the defroster (small), the defroster (large) and the bottom air outlet
(small), and the defroster.
b. Rotate the wind direction adjustment knob on air condition controller, the wind direction adjustment knob
drives the mode throttle and controls the mode throttle actuator to run, so as to achieve the conversion of
blowing modes.
5. Internal and external circulation throttle control

a. Air condition controller accepts the switch signal of internal and external circulation selection button and
controls the internal and external circulation motorto run, and then drives the internal and external circulation
throttle position to change,so as to achieve the switching of internal and external circulation.

DI-168