Nissan Versa

 Sedan Service Manual

Ventilation, heater & air conditioner » Heater & air conditioning control system (HAC) » Manual air conditioning system
Manual air conditioning system : Compressor Control

DESCRIPTION

• When A/C switch signal is received from front air control, the thermo control amp. transmits A/C ON signal to the BCM according to evaporator fin temperature.
• When the front blower motor is operated, the front air control transmits blower fan ON signal to the BCM.
• BCM transmits the A/C ON signal and blower fan ON signal to ECM via CAN communication line. Refer to EC"CAN COMMUNICATION : System Description"
• ECM judges the conditions of each sensor (Refrigerant pressure sensor signal, accelerator position signal, etc.), and transmits the A/C compressor request signal to IPDM E/R via CAN communication line.
• By receiving the A/C compressor request signal from ECM, IPDM E/R turns the A/C relay to ON, and activates the compressor. Refer to PCS "RELAY CONTROL SYSTEM : System Description" or PCS "RELAY CONTROL SYSTEM : System Description"

CONTROL BY THERMO CONTROL AMP.

Low Temperature Protection Control

• When thermo control amp. detects that evaporator fin temperature is 1.5C (35F) or less, thermo control amp. switches A/C ON signal to OFF and stops the compressor.

  When the evaporator fin temperature returns to 3C (37F) or more, the compressor is activated.

CONTROL BY ECM

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

Compressor Oil Circulation Control

When the engine starts while the engine coolant temperature is 56C (133F) or less, ECM activates the compressor for approximately 6 seconds and circulates the compressor oil once.

Air Conditioning Cut Control

When the engine is under a high load condition, the ECM transmits an A/C relay OFF request to IPDM E/R, and stops the compressor. Refer to EC "AIR CONDITIONING CUT CONTROL : System Description".

Manual air conditioning system : Compressor Control

Manual air conditioning system : Door Control