Air Conditioner

AIR CONDITIONER CONTROL SYSTEM
Air conditioner control system consists of the A/C switch in the function control panel, A/C control unit, evaporator, dual pressure switch, radiator fan control unit, engine coolant temperature sensor, pressure switch, PGM-FI ECU, magnetic clutch, and the clutch relay.





SYSTEM OPERATION
When the A/C switch and blower motor switch ON, the A/C control unit sends a signal through the dual pressure switch to the radiator fan control unit. If the evaporator sensor temperature is over 4°C (39° F), the radiator fan control unit activates the cooling fans and sends a signal to the PGM-FI ECU. The ECU then increases engine idle speed and energizes the A/C compressor clutch.

When the temperature at the evaporator drops below 3°C (37° F) the sensor signals the control unit to turn off the fans and compressor.

TRIPLE PRESSURE SWITCH OPERATION
If the refrigerant pressure becomes too high (due to blockage) or too low (due to leakage) the triple pressure switch sends a signal to the cooling fan control unit to prevent the A/C from operating.

Pressure Sensor:

When the system pressure is high (due to heavy operation in high temperature), triple pressure switch is activated to run the cooling fans at a higher speed.
If engine coolant temperature reaches 109 C (228°F) at the coolant temperature sensor, the A/C is shut off.