Description

SYSTEM DESCRIPTION

The Variable Displacement Orifice Tube (VDOT) refrigeration system employs the constant-run V-5 compressor. The V-5 is a variable displacement compressor that can match the air conditioning demand under all conditions without cycling. The basic compressor mechanism is a variable angle wobble-plate with 5 axial oriented cylinders. A bellows-actuated control valve located in the rear head of the compressor senses compressor suction pressure and controls compressor displacement. The wobble-plate angle and compressor displacement are controlled by the crankcase-suction pressure differential.

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.

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. The angle of the wobble-plate is controlled by a force balance on the 5 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 that reduces the plate angle.

When the engine is turned off with the air conditioning 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. This is a normal condition.

The air conditioning system that is available for this vehicle is described below:

- C-60--Front Manual Controls, HVAC System