Compressor Control
SYSTEM
Compressor Control
DESCRIPTION
In order for the IPDM E/R to complete a compressor ON request, the following conditions must be met:
1.The BCM detects a Fan ON signal from the front air control. The front air control grounds the fan ON signal monitored by the BCM when the blower speed dial is in any of the fan speed positions.
2.The BCM detects an A/C ON signal from the front air control. The front air control grounds the A/C ON signal monitored by the BCM when:
-The A/C switch is pressed. The A/C switch LED illuminates and the front air control grounds the A/C ON
signal monitored by the BCM. Any mode control button except D/F may be selected.
-The A/C switch is OFF, and the MAX A/C button is pressed. The A/C switch LED will automatically illuminate and the front air control grounds the A/C ON signal monitored by the BCM.
-The A/C switch is OFF, and the mode button for either D/F or DEF is selected. The front air control grounds the A/C ON signal monitored by the BCM, but it does not illuminate the A/C switch LED
NOTE:
If the compressor was engaged by pressing the D/F or DEF mode buttons, and the time spent in either mode exceeds 1 minute, then the compressor stays requested, even when modes other than D/F or DEF are selected, until either:
1.The ignition switch is turned OFF.
2.The blower speed dial is turned completely counterclockwise to the OFF position.
3.The A/C switch is manually turned OFF.
In other words, the compressor ON request cannot be turned off in D/F or DEF modes.
REFRIGERANT PRESSURE PROTECTION
The refrigerant system is protected against excessively high- or low-pressures by the refrigerant pressure sensor, located on the liquid tank on the condenser. The refrigerant pressure sensor detects the pressure inside the refrigerant line and sends a voltage signal to the ECM. If the system pressure rises above or falls below the following values, the ECM requests the IPDM E/R to de-energize the A/C relay and disengage the compressor.
- 3.12 MPa (31.82 kg/cm2, 452.4 psi) or more (When the engine speed is less than 1,500 rpm)
- 2.74 MPa (27.95 kg/cm2, 397.3 psi) or more (When the engine speed is 1,500 rpm or more)
- 0.14 MPa (1.43 kg/cm2, 20.3 psi) or less
PRESSURE RELIEF VALVE
The refrigerant system is also protected by a pressure relief valve, located in the rear head of the compressor.
When the pressure of refrigerant in the system increases to an abnormal level [more than 2,990 kPa (30.5 kg/
2
cm, 433.6 psi)], the release port on the pressure relief valve automatically opens and releases refrigerant into the atmosphere.
COMPRESSOR OIL CIRCULATION CONTROL
When the engine starts while the engine coolant temperature is 56�C (133�F) or less, ECM activates the compressor for approximately 6 seconds and circulates the compressor lubricant once.
LOW TEMPERATURE PROTECTION CONTROL
- When the intake sensor detects that the front evaporator fin temperature is 1.5�C (35�F) or less, the front air control requests the BCM to turn the compressor OFF, and stops the compressor.
- When the front evaporator fin temperature returns to 5.0�C (41�F) or more, the compressor is activated.
OPERATING RATE CONTROL
When the set temperature is other than fully cold or the air outlet is "VENT", "B/L" or "FOOT", the front air control controls the compressor activation depending on ambient temperature.