For 1990-2009 cars

### Variable Displacement Orifice Tube (VDOT)

(1) | Compressor
(2) | Condenser
(3) | Evaporator
(4) | Accumulator
(5) | Low Pressure Liquid
(6) | Low Pressure Vapor
(7) | High Pressure Liquid
(8) | High Pressure Vapor
(9) | Expansion (Orifice) Tube
(10) | Liquid Line
(11) | Pressure Relief Valve

The variable displacement orifice tube (VDOT) system consists of the following components:

• | A variable displacement compressor (1)

• | A fixed expansion tube (5)

This system matches the air conditioning demands under all conditions, without cycling. The basic compressor mechanism is a variable angle wobble-plate with 5 axially oriented cylinders. The center of control of the compressor displacement is a bellows-actuated control valve. The valve is located in the rear head of the compressor. The valve senses compressor suction pressure. The crankcase-suction pressure differential controls the following items:

• | The wobble-plate angle

• | The compressor displacement

When the A/C capacity demand is high, the suction pressure will be above the control point. The valve will maintain a bleed of discharge gas into the crankcase and close off a passage from the crankcase to the suction plenum. A force balance on the 5 pistons controls the angle of the wobble-plate. A slight elevation of the crankcase-suction pressure differential creates a total force on the pistons that results in a movement about the wobble-plate pivot pin. The movement reduces the plate angle.