Buick LeSabre 1965 Service Manual page 781

COMPRESSOR-
COMPRESSES THE LOW
PRESSURE REFRIGERANT
TO A HIGH PRESSURE.
STV VACUUM DIAPHRAGM SETS VALVE-^
TO INCREASE EVAPORATOR PRESSURE
(DECREASE COOLINGJ.WHEN AV£
PRESENT AT DIAPHRAGM M A X .
COOLING OBTAINED.
MINIMUM COOLING OBTAINED
WHEN THERE IS NO V A C U U M
PRESENT AT DIAPHRAGM.
-BLEEDUNE PERMITS OIL AND REFRIGERANT
TO FLOW FROM BOTTOM OF EVAPORATOR
INTO S T V OUTLET AND TO COMPRESSOR
WHEN CHECK VALVE IS OPEN. TO INSURE
OH. WILL BE RETURNED TO COMPRESSOR
IF SYSTEM IS LOW ON REFRIGERANT
OR IP COMPRESSOR CAPACITY
EXCEEDS EVAPORATOR DEMANDS.
fV—TO VACUUM SOURCE
I f * — MAX. COOLING
rpz\ I VACUUM SWITCH
CHECK VALVE
( O U T OF LOCATION)
STARTS TO OPEN WHEN
EVAPORATOR INLET
PRESSURE IS 5 P.S.I
HIGHER T H A N S T V
OUTLET PRESSURE.
IS FULLY OPENED
AT I2RSJ.
CAPILLARY TUBE
-EXPANSION VALVE
SUCTION LINE
RECEIVER OEHYDRATOR-
-EVAPORATC
AIR PASSING OVER EVAPORATOR
LOSES HEAT TO LOW PRESSURE
LIQUID WHICH EVAPORATES TO A
GAS ALSO.AIR LOSES MOSTURE
TO THE COLD SURFACE OF THE
EVAPORATOR.
SUCTION THROTTLE VAIVE (STV)
AUTOMATICALLY MAINTAINS EVAPORATOR
PRESSUREt EVAPORATOR OUTLET AIR
TEMPERATURE) AND PREVENTS EVAPORATOR
CORE FREEZE - U P .
RECEIVER ACTS AS A RESERVOIR TO
x
FURNISH A SOLID COLUMN OF LIQUID
TO EXPANSION VALVE DEHYDRATOR
FILTER ABSORBS MOISTURE AND
TRAPS FOREIGN MATERIAL PRESENT
IN SYSTEM.
ilGHT GL/
USED AS SYSTEM
DIAGNOSIS AID TO
DETERMINE REFRIGERANT
SHORTAGE.
AUTOMATICALLY CONTROLS
REFRIGERANT FLOW INTO
EVAPORATOR. THE VALVE'S
PRESSURIZED BULB CONTROLS
THE OPENING OF THE VALVE TO
MAINTAIN HIGHER REFRIGERANT
TEMPERATURE AT EMVPORATOR OUTLET
TO INSURE REFRIGERANT REMAINS IN
EVAPORATOR LONG ENOUGH TO
COMPLETELY VAPORIZE AND
REMOVE HEAT FROM AIR.
• PRESSURE EQUALIZER LINE
THE EXPANSION VALVE'S PRESSURE
EQUALIZER LINE PERMITS S T V
OUTLET PRESSURE TO BE
IMPOSED ON THE VALVE'S
DIAPHRAM TO PREVENT THE S T V
OUTLET PRESSURE FROM DROPPING
BELOW A PREDETERMINED PRESSURE.
(WHEN THE COMPRESSOR CAPACITY
BECOMES GREATER THAN
EVAPORATOR LOAD. THE DROP IN THE
S T V OUTLET PRESSURE FORCES THE
EXPANSION VALVE TO FLOOD LIQUID
THROUGH EVAPORATOR AND INCREASE
EVAPORATOR OUTLET PRESSUREJ
m HIGH PRESSURE GAS
( H I HIGH PRESSURE LIQUID
HUD LOW PRESSURE LIQUID
g g g LOW PRESSURE QAS-EVAPORATOR OUTLET
E 3 LOW PRESSURE G A S - S T V OUTLET
(COMPRESSOR SUCTION)
LIQUID
LINE —
O
o
m
5
m
70
O
o
g
O
LIQUID LINE
>
o
o
m
8
70
Figure 11-58—Air Conditioner Refrigerant Circuit - 45000, 46000 and 48000 Series