TM 9-2320-280-20-1
1-32. M997, M997A1, AND M997A2 AMBULANCE AIR-CONDITIONING
SYSTEM OPERATION
The air-conditioning system covered in this manual applies only to the M997, M997A1, and M997A2
vehicles and consists of the following major components:
COMPRESSOR - Inside the compressor, low pressure gas refrigerant is compressed into a high
pressure gas that is pushed into the condenser by the compressor.
DISCHARGE LINE - High pressure gas is carried through the discharge line from the compressor
to the condenser.
CONDENSER - Refrigerant enters the condenser as a high pressure gas. When condensed, it
gives up its heat to the outside air and becomes a high pressure liquid.
LIQUID LINE - High pressure liquid refrigerant is carried back to the evaporator by the liquid
line to repeat the evaporation/condensation cycle.
EXPANSION VALVE - High pressure liquid refrigerant enters a non-adjustable expansion valve
where the refrigerant is formed into a liquid spray.
EVAPORATOR - Refrigerant enters evaporator as a liquid spray. It absorbs heat from the air in
the patient compartment and vaporizes into a low pressure gas.
SUCTION LINE - Refrigerant in low pressure gas form is drawn from the evaporator by the
suction action of the compressor.
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