Engine Cooling System (Electronic Fan) Control - Lifan 620 Maintenance Manual

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Security protection control mainly guarantees the normal operation of the system. Monitoring the
system pressure and temperature by the pressure switch installed on the high-pressure hard pipe
can realize the security protection control. Functions of security protection control as follows:
(1) Low pressure protection: for pressure below 0.196±0.02 MPa, pressure switch (between 1-A4
and 3-A4) switches off, the power of compressor clutch is cut off, and compressor stops working;
(2) Over pressure protection: for pressure over 3.14±0.2 MPa, pressure switch (between 1-A4 and
3-A4) switches off, the power of compressor clutch is cut off, and compressor stops working;
(3) Control high pressure: for pressure over or equal to 1.77±0.1 MPa, pressure switch (between
2-A4 and 4-A4) switches on, a trigger signal is sent to engine ECM to make the electronic fan work
at high speed;
(4) Low temperature protection: for temperature below 2℃ sensed by evaporator temperature
sensor, the power of compressor clutch is cut off, and compressor stops working;
(5) High temperature protection: for temperature over 110.25 ℃ sensed by coolant temperature
sensor, apply overheat protection for compressor; the power of compressor clutch is cut off, and
compressor stops working.
4. Engine cooling system (electronic fan) control. Engine cooling system control consists of
coolant temperature sensor, engine ECM, 1#, 2#, 3# electronic fan control relay, cooling fan,
cooling fan regulation resistance, condensation fan and relevant circuits. Depending on relevant
temperature sensors and switching signals, engine ECM controls the on off state of relevant fan
control relay circuits, as follows:
(1) For coolant temperature of 93 ~96 , ℃ ℃ engine ECM electrifies 1# relay and 3# relay; the 2
electronic fans are connected in parallel and work at low speed simultaneously.
(2) For coolant temperature of 98 ~100 , ℃ engine ECM electrifies 2# relay; cooling fan works at
℃
high speed.
(3) For coolant temperature reaching 110℃, instrument cluster lightens the warning lamp.
(4) For air conditioner switch closing, electronic fan works at low speed no matter coolant
temperature is high or low.
(5) For the pressure of air conditioning refrigeration system over or equal to 1.77±0.1MPa,
electronic fan works at high speed.
(6) For abnormal coolant temperature signals (broken coolant temperature sensor), engine ECM
will judge the engine runs with heavy load, electronic fan works at high speed.
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