R134a Electric AC Compressor For Lexus -GS 2005-2011 S190 - 450h Lexus USA - GS 450h 2004-2011 - 3.5 V6Hybrid Toyota

R134a Electric AC Compressor For Lexus -GS 2005-2011 S190 - 450h Lexus USA - GS 450h 2004-2011 - 3.5 V6Hybrid Toyota

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Theory

Principles of Air Conditioning

(Expansion Valve System)

1)High pressure side

Low pressure R134a vapor entering the compressor is compressed to become high pressure/temperature R134a vapor. This is then circulated along with lubricant oil to the condenser. As the high pressure/temperature vapor travels through the condenser, heat is released to the cooler ambient air passing over the condenser tubes condensing the vapor into a liquid. This high pressure/temperature liquid then travels through the filter drier onto the expansion valve where a small variable orifice provides a restriction against which compressor pushes.

2) pressure side

Suction from the compressor pulls the high pressure/temperature liquid R134a through small variable orifice of the TX valve and into the low-pressure side of the A/C system.

The R134a is now under low pressure/temperature vapor where heat from the cabin being blown over the evaporator coil surface is absorbed into the colder low pressure refrigerant The R134a is then pulled through the evaporator and into the

compressor.

The A/C cycle begins again as the R134a vapor is compressed and discharged under pressure.

3)Heat transfer

R134a in the LOW-PRESSURE side is COLD and can absorb large quantities of heat from the air moving over the evaporator.

R134a in HIGH-PRESSURE side is HOT and the cooler ambient air moving over the condenser can absorb the heat from it.

Summary

- When the R134a pressure is low, the R134a temperature is low.

- When the R134a pressure is high, the R134a temperature is high.

Compressors :

1) Rotary Vane - Panasonic

Rotary vane compressors consist of a rotor with three or four vanes and a carefully shaped

rotor housing. As the compressor shaft rotates, the vanes and housing form chambers.

The R134a is drawn through the suction port into these chambers, which become smaller as

the rotor turns. The discharge port is located at the point where the gas is fully compressed.

The vanes are sealed against the rotor housing by centrifugal force and lubricating oil. The

oil sump and oil pump are located on the discharge side, so that the high pressure forces oil

through the oil pump and then onto the base of the vanes keeping them sealed against the

rotor housing.

During idle an occasional vane noise from the compressor may be heard. This is due to the

time taken for lubricating oil to circulate through the A/C system.

2)Scroll type - Sanden

This compressor uses a unique design with two scrolls, one fixed and one is movable, both are inter-leaved.

The movable spiral is able to ORBIT or oscillate without actually fully rotating. The movable scroll is connected

to the input shaft via a concentric bearing.

As the movable spiral oscillates within the fixed spiral, a number of pockets are formed between the spiral. As

these pockets decrease in size the refrigerant is squeezed, the pressure increases and is discharged

through a reed valve at the discharge port in the rear section of the compressor.

3)Variable stroke - Harrison V5

The Delphi (Harrison) V5 compressor is a non-cycling variable displacement compressor.

The compressor varies displacement to control capacity to meet A/C system demand at all operating conditions. The compressor features a variable angle wobble plate in five (V5) cylinder axial piston design.

Displacement is controlled by a bellows actuated control valve located in the rear cylinder head. This control valve senses and responds to the system suction pressure or A/C system demand.

Through regulation of compressor crankcase pressure, the wobble plate angle, and therefore compressor displacement is variable.

In general, the compressor discharge pressure is much greater than the compressor crankcase. Which is greater than or equal to the compressor suction pressure.

At maximum displacement, compressor crankcase pressure is equal to the compressor suction pressure.

At reduced or minimum displacement, the compressor crankcase pressure is greater than the suction pressure.

Compressors and Mount & Drive:

Mount & Drive

Consists of a bracket to mount the compressor to the engine, a belt idler pulley, compressor

drive belt and possibly and extra drive pulley for the crankshaft.

Compressor Mount

Manufactured of either plate, cast iron, steel or aluminium, this bracket should exhibit

excellent noise absorption qualities especially if using a piston type compressor.

Idler Pulley

A small pulley normally used in conjunction with a belt adjusting mechanism, also used when

a belt has a long distance between pulleys to absorb belt vibrations.

Drive Pulley

Some vehicles do not have an extra pulley to accommodate an A/C drive belt, in these

cases an extra pulley is bolted onto the existing crankshaft pulley.

Clutches:

The clutch is designed to connect the rotor pulley to the compressor input shaft when the field coil is energized. The clutch is used to transmit the power from the engine crankshaft to the compressor by means of a drive belt.

When the clutch is not engaged the compressor shaft does not rotate and refrigerant does not circulate the rotor pulley free wheels. The field coil is actually an electromagnet, once energized it draws the pressure plate towards it, locking the rotor pulley and the pressure plate together causing the compressor internals to turn, creating pressure and circulating refrigerant.

Evaporation:

Is the term used when enough heat is added to a liquid substance to change it into a vapor (gas). For example, when water is boiled.

This condition occurs within the A/C system.

Condensers:

The Condenser function is to act as a heat exchanger and allow heat to flow from the hot

refrigerant to the cooler outside air.

R134a entering the condenser will be a high-pressure high temperature vapor. As the R134a

vapor travels through the tubes of the condenser heat is given off to the cooler ambient air; the

refrigerant vapor condenses and changes to a liquid state.

At this point a large amount of heat is given off by the R134a. The refrigerant will now be a hot,

high pressure liquid.