FIXED DISPLACEMENT A/C COMPRESSOR

The Denso 10SR15 and 10SR17 fixed displacement A/C compressors are driven by the engine through an electric clutch, drive pulley and belt arrangement. These A/C compressors are lubricated by refrigerant oil that is circulated throughout the refrigerant system with the refrigerant.

The A/C compressors draw in low-pressure refrigerant vapor from the A/C evaporator through the suction port, then compresses the refrigerant into a high-pressure, high-temperature refrigerant vapor, which is pumped to the A/C condenser through the compressor discharge port.

CAUTION: Be certain to adjust the refrigerant system oil level when replacing an A/C compressor. Failure to properly adjust the refrigerant oil level can prevent the A/C system from operating as designed and can cause serious A/C compressor damage.

The Denso 10SR15 and 10SR17 fixed displacement A/C compressors cannot be repaired and must be replaced if inoperative or damaged. The compressor clutch, pulley and bearing assembly, and clutch field coil are available for service if inoperative or damaged. If an internal failure of the A/C compressor has occurred, the A/C receiver/drier must also be replaced.

VARIABLE DISPLACEMENT A/C COMPRESSOR

Fig. 204: 5SE12C Compressor-Operation

NOTE: Typical variable displacement A/C compressor shown.

The Denso 6SEU16 A/C compressor is a variable displacement compressor (VDC) which is driven by the engine through a drive hub (1) and pulley (2). This A/C compressor does not require the use of an electromagnetic clutch, as the compressor uses an integral control solenoid (3) to reduce or increase the stroke of the five pistons (4) within the compressor by automatically adjusting the angle of the swashplate (5).

The A/C compressor draws in low-pressure refrigerant vapor from the A/C evaporator through its suction port.

It then compresses the refrigerant into a high-pressure, high-temperature refrigerant vapor, which is then pumped to the A/C condenser through the compressor discharge port. The A/C compressor is lubricated by refrigerant oil that is circulated throughout the refrigerant system with the refrigerant.

The A/C compressor is controlled by the powertrain control module (PCM) or engine control module (ECM), depending on engine application. The PCM/ECM calculates compressor displacement required by A/C system load and demand by monitoring vehicle speed, A/C high side pressure, engine speed, evaporator temperature, accelerator pedal position, ambient temperature and A/C-heater request signals. The PCM/ECM then sends a pulse width modulated (PWM) signal to the A/C compressor control solenoid to increase or decrease refrigerant flow through an orifice located within the compressor housing. The amount of refrigerant allowed to pass through the orifice in the compressor determines the head pressure which controls the angle of the swashplate, which in turn, determines the amount of compressor displacement. When there is no demand for A/C, the swashplate is adjusted to nearly a zero degree angle, which removes compressor torque drag from the engine.

This A/C compressor will reduce the displacement of the compressor based on ambient air temperature. For example; as the outside temperature falls from 27º C (80º F) to 19º C (66º F), the amount of refrigerant flow required through the A/C orifice valve to keep the A/C evaporator cool becomes less, and the swashplate is adjusted to a lower angle, which reduces compressor displacement. However, due to the lower outside air temperature, panel air outlet temperature will not noticeably change.

The A/C compressor control system is diagnosed using a scan tool.

CAUTION: Do NOT run the engine with a vacuum pump in operation or with a vacuum present within the A/C system when equipped with a variable displacement A/C compressor. Failure to follow this caution will result in serious A/C compressor damage.

CAUTION: Be certain to adjust the refrigerant system oil level when replacing an A/C compressor. Failure to properly adjust the refrigerant oil level can prevent the A/C system from operating as designed and can cause serious A/C compressor damage.

NOTE: The compressor drive hub and the pulley and bearing assembly can not be serviced separately from the A/C compressor. In the event of drive hub or pulley and bearing assembly damage or failure, the A/C compressor, drive hub and pulley and bearing must be replaced as an assembly.

The A/C compressor cannot be adjusted or repaired and must be replaced if inoperative or damaged. If an internal failure of the A/C compressor has occurred, the A/C receiver/drier must also be replaced.

CLUTCH - FIXED DISPLACEMENT A/C COMPRESSOR

The clutch components for the Denso 10SR15 and 10SR17 fixed displacement A/C compressor provide the means to engage and disengage the compressor from the engine accessory drive belt. When the electromagnetic A/C clutch field coil is energized, it magnetically draws the clutch plate into contact with the clutch pulley and drives the compressor shaft. When the coil is not energized, the pulley freewheels on the clutch hub bearing, which is part of the pulley assembly.

A/C compressor clutch engagement is controlled by the powertrain control module (PCM) or the engine control module (ECM), depending on engine application. When the A/C-heater control is set to any A/C position, it sends a request signal on the CAN-IHS bus to the totally integrated power module (TIPM), which then transfers the request on the CAN-C Bus to the PCM/ECM, which determines if operating conditions are correct for A/C clutch engagement. When all operating conditions have been met, the PCM/ECM sends a signal on a dedicated hard-wired circuit back to the totally integrated power module (TIPM) to energize the internal A/C clutch high side driver. When energized, the A/C clutch high side driver provides battery current to the A/C clutch field coil.

The A/C clutch control system is diagnosed using a scan tool.

The A/C compressor clutch components cannot be adjusted or repaired and must be replaced if inoperative or damaged.

HUB AND PULLEY - VARIABLE DISPLACEMENT A/C COMPRESSOR

Fig. 205: A/C Compressor Hub

NOTE: Typical clutchless compressor pulley drive hub shown.

The design of the Denso 6SEU16 variable displacement A/C compressor does not require the use of an electromagnetic clutch, as the compressor is controlled by an integral control valve that allows refrigerant to bypass within the compressor.

The three bridges (1) located on compressor drive hub (2) are designed to break away in the event of compressor seizure. This action prevents damage to the serpentine accessory drive belt.

NOTE: The compressor drive hub and the pulley and bearing assembly can not be serviced separately from the A/C compressor. In the event of drive hub or pulley and bearing assembly damage or failure, the A/C compressor, drive hub and pulley and bearing must be replaced as an assembly.

The compressor drive hub and the pulley and bearing assembly can not be serviced separately from the A/C compressor. The A/C compressor must be replaced if the drive hub or pulley and bearing assembly is worn or damaged.

HIGH PRESSURE RELIEF VALVE

The high pressure relief valve vents refrigerant from the A/C system when a discharge pressure of 3445 to 4135 kPa (500 to 600 psi) or above is reached. The high pressure relief valve closes with a minimum discharge pressure of 2756 kPa (400 psi) is reached.

The high pressure relief valve should not open when the A/C system is operating correctly. If the high pressure relief valve vents refrigerant, there is most likely a problem within the A/C refrigerant system. The high pressure relief valve vents only enough refrigerant to reduce the A/C system pressure, and then re-seats itself. If the high pressure relief valve vents refrigerant, see the A/C System Diagnosis chart. The high pressure relief valve is factory-calibrated and cannot be adjusted or repaired, and must not be removed or otherwise disturbed. The valve is only serviced as a part of the A/C compressor.