Control curve for variable delivery compressor

A method of adjusting an air conditioner compressor for a selected vehicle, the compressor having an intake valve which is varied by a valve actuator controlled by control pressure supplied by a control valve, the control valve having a discharge port for receiving compressor discharge pressure, a suction port for receiving compressor suction pressure, a control pressure port which communicates with the suction pressure port and the discharge pressure port for supplying the control pressure to the valve actuator, a movable valve element which moves between open and closed positions to vary the control pressure by opening and closing communication of the suction pressure to the control pressure port, a bellows which has an exterior exposed to suction pressure and an end which acts against the valve element to urge it to an open position in response to changes in the effective length of the bellows, and a movable bias pin which has a pressure area exposed to the discharge pressure and acts against the valve element in a direction opposite to the bellows to urge the valve element to the closed position, the method comprising:

• (a) installing the compressor in the vehicle and operating the vehicle under a selected high demand operating condition;
• (b) sensing suction pressure, discharge pressure, and grill air temperature off an air conditioner blower while the vehicle is being operated under the high demand operating condition;
• (c) adjusting the effective length of the bellows to provide a desired suction pressure set point at which the grill air temperature at the high demand operating condition is satisfactory;
• (d) operating the vehicle at a selected low demand operating condition and determining an evaporator outlet pressure;
• (e) if the evaporator outlet pressure is not a desired magnitude at the low demand operating condition, changing the pressure area of the bias pin and repeating steps (b) through (e) until the desired suction pressure set point is reached and the evaporator outlet pressure is at the desired magnitude.

A method of adjusting an air conditioner compressor for a selected vehicle, the compressor having an intake valve which is varied by a valve actuator controlled by control pressure, the method comprising:

• (a) providing the compressor with a control valve cavity having a discharge port for receiving compressor discharge pressure, a suction port for receiving compressor suction pressure, and a control pressure port which supplies the control pressure to the valve actuator;
• (b) inserting into the control valve cavity a first modular control valve having a movable valve element which moves between open and closed positions to vary the control pressure by opening and closing communication of the suction pressure to the control pressure port, a bellows which has an exterior exposed to suction pressure and an end which acts against the valve element to urge it to an open position in response to changes in the effective length of the bellows, and a movable bias pin which has a pressure area exposed to the discharge pressure and acts against the valve element in a direction opposite to the bellows to urge the valve element to the closed position;
• (c) installing the compressor in the vehicle with the first modular control valve and operating the vehicle under a selected high demand operating condition;
• (d) sensing suction pressure, discharge pressure, and grill air temperature off an air conditioner blower while the vehicle is being operated under the high demand operating condition;
• (e) adjusting the effective length of the bellows to provide a desired suction pressure set point at which the grill air temperature at the high demand operating condition is satisfactory;
• (f) operating the vehicle at a selected low demand operating condition and determining an evaporator outlet pressure;
• and
• (g) if the evaporator outlet pressure is not a desired magnitude, removing the first modular control valve from the cavity, and installing a second modular control valve which has a bias pin with a different pressure area than the bias pin of the first modular control valve;
• and repeating steps (c) through (g) until the desired suction pressure set point is reached and the evaporator outlet pressure is at the desired magnitude.