With Air Conditioning
DESCRIPTIONThe Variable Displacement Orifice Tube (VDOT) refrigeration system employs the constant run V-5 compressor. The V-5 is a variable displacement compressor which can match A/C demand under all conditions without cycling.
DESIGN
The basic compressor mechanism is a variable angle wobble-plate with five axial oriented cylinders. The compressor displacement center of control is a bellows actuated control valve located in the rear head of the compressor which senses compressor suction pressure. The wobble plate angle and compressor displacement are controlled by the crankcase suction pressure differential.
The angle of the wobble-plate is controlled by a force balance on the five pistons. A slight elevation of the crankcase suction pressure differential creates a total force on the pistons, resulting in a movement about the wobble-plate pivot pin, reducing the plate angle.
OPERATION
High Demand
When the air conditioning capacity demand is high, the suction pressure will be above the control point and the valve will maintain a bleed from crankcase to suction. When no crankcase suction pressure differential exists, the compressor will have maximum displacement.
Low Demand
When the air conditioning capacity demand is lower and the suction pressure reaches the control point, the valve will bleed discharge gas into the crankcase and close off a passage from the crankcase to the suction plenum.
Engine Off
When the engine is turned off with the A/C system operating, the refrigerant in the system will flow from the high pressure side of the orifice tube to the low pressure side until the pressure is equalized. This may be detected as a faint sound of liquid flowing (hissing) for 30 to 60 seconds and is a normal condition.