Terex TS14G, Maintenance Manual

Page: 315 / 376

Section 260-0130
SM 1787 Rev1 03-04
1
DESCRIPTION
Temperature Control Switch
A thermostat switch senses the temperature of the
evaporator and engages or disengages the compressor
clutch. The control for this switch is located in the cab.
Compressor
The compressor is designed to compress vapour and
can be damaged by non-compressibles such as dirt,
moisture, liquid refrigerant (R-134a), etc. The
compressor draws vaporized R-134a from the
evaporator (which maintains the low pressure
necessary for proper evaporation) and compresses the
vapour to a high pressure, which is necessary for
condensation. The high pressure vapour then moves
into the condenser where heat can be radiated to
change the R-134a back to liquid.
Note: R-134a designates the type of refrigerant used in
heavy duty vehicle air conditioning systems.
Compressor Drive Clutch
The R-134a compressor systems use an electronically
actuated clutch to engage and disengage drive to the
compressor. The 'V' belt pulley is mounted on a bearing
and is free to rotate without turning the compressor
crankshaft any time electrical power is disconnected. The
compressor is not operating when the pulley is
freewheeling. The field coil is energized by supplying
electrical current to the exposed wire. The other end of the
coil winding is grounded to the compressor and equipment
frame. Energizing the coil creates a magnetic force that
locks the driven disk to the pulley and drives the
compressor.
Condenser
The purpose of the condenser is to radiate enough heat
energy from the compressed high pressure vaporized
R-134a so that the R-134a changes from vapour to
liquid. During normal operation all the high pressure
section of the system will be warm or hot, but large
quantities of heat should be radiating from the
condenser. Nothing should be permitted to stop or slow
Fig. 1 - Typical Air Conditioning Flow Diagram
SM - 572
1 - Compressor
2 - Condenser 3 - Receiver Drier
4 - Expansion Valve 5 - Evaporator
6 - Sensing Bulb
OPERATORS COMPARTMENT - Air Conditioning
Courtesy of Machine.Market