2004 DAEWOO LACETTI Vacuum valve

ENGINE CONTROLS 1F – 625
DAEWOO V–121 BL4
EVAPORATIVE EMISSION CANISTER
The Evaporative (EVAP) Emission canister is an emission
control device containing activated charcoal granules.
The EVAP emission canister is used to store fuel vapors
from the fuel tank. Once certain conditions are met, the en-
gine control module (ECM) activates the EVAP canister
purge solenoid, allowing the fuel vapors to be drawn into
the engine cylinders and burned.
POSITIVE CRANKCASE
VENTILATION SYSTEM OPERATION
A Positive Crankcase Ventilation (PCV) system is used to
provide complete use of the crankcase vapors. Fresh air
from the air cleaner is supplied to the crankcase. The fresh
air is mixed with blowby gases which are then passed
through a vacuum hose into the intake manifold.
Periodically inspect the hoses and the clamps. Replace
any crankcase ventilation components as required.
A restricted or plugged PCV hose may cause the following
conditions:
S Rough idle
S Stalling or low idle speed
S Oil leaks
S Oil in the air cleaner
S Sludge in the engine
A leaking PCV hose may cause the following conditions:
S Rough idle
S Stalling
S High idle speed
ENGINE COOLANT TEMPERATURE
SENSOR
The Engine Coolant Temperature (ECT) sensor is a
thermistor (a resistor which changes value based on tem-
perature) mounted in the engine coolant stream. Low cool-
ant temperature produces a high resistance (100,000
ohms at –40 °F [–40 °C]) while high temperature causes
low resistance (70 ohms at 266 °F [130 °C]).
The engine control module (ECM) supplies 5 volts to the
ECT sensor through a resistor in the ECM and measures
the change in voltage. The voltage will be high when the
engine is cold, and low when the engine is hot. By measur-
ing the change in voltage, the ECM can determine the
coolant temperature. The engine coolant temperature af-
fects most of the systems that the ECM controls. A failure
in the ECT sensor circuit should set a diagnostic trouble
code P0117 or P0118. Remember, these diagnostic
trouble codes indicate a failure in the ECT sensor circuit,
so proper use of the chart will lead either to repairing a wir-
ing problem or to replacing the sensor to repair a problem
properly.
THROTTLE POSITION SENSOR
The Throttle Position (TP) sensor is a potentiometer con-
nected to the throttle shaft of the throttle body. The TP sen-
sor electrical circuit consists of a 5 volt supply line and a
ground line, both provided by the engine control module
(ECM). The ECM calculates the throttle position by moni-
toring the voltage on this signal line. The TP sensor output
changes as the accelerator pedal is moved, changing the
throttle valve angle. At a closed throttle position, the output
of the TP sensor is low, about 0.5 volt. As the throttle valve
opens, the output increases so that, at Wide Open Throttle
(WOT), the output voltage will be about 5 volts.
The ECM can determine fuel delivery based on throttle
valve angle (driver demand). A broken or loose TP sensor
can cause intermittent bursts of fuel from the injector and
an unstable idle, because the ECM thinks the throttle is
moving. A problem in any of the TP sensor circuits should
set a diagnostic trouble code (DTC) P0121 or P0122.
Once the DTC is set, the ECM will substitute a default val-
ue for the TP sensor and some vehicle performance will
return. A DTC P0121 will cause a high idle speed.
CATALYST MONITOR OXYGEN
SENSORS
Three–way catalytic converters are used to control emis-
sions of hydrocarbons (HC), carbon monoxide (CO), and
oxides of nitrogen (NOx). The catalyst within the convert-
ers promotes a chemical reaction. This reaction oxidizes
the HC and CO present in the exhaust gas and converts
them into harmless water vapor and carbon dioxide. The
catalyst also reduces NOx by converting it to nitrogen. The
engine control module (ECM) can monitor this process us-
ing the HO2S1 and HO2S2 sensor. These sensors pro-
duce an output signal which indicates the amount of oxy-
gen present in the exhaust gas entering and leaving the
three–way converter. This indicates the catalyst’s ability to
efficiently convert exhaust gasses. If the catalyst is operat-
ing efficiently, the HO2S1 sensor signals will be more ac-
tive than the signals produced by the HO2S2 sensor. The
catalyst monitor sensors operate the same way as the fuel
control sensors. The sensor’s main function is catalyst
monitoring, but they also have a limited role in fuel control.
If a sensor output indicates a voltage either above or below
the 450 mv bias voltage for an extended period of time, the
ECM will make a slight adjustment to fuel trim to ensure
that fuel delivery is correct for catalyst monitoring.
A problem with the HO2S1 sensor circuit will set DTC
P0131, P0132, P0133 or P0134 depending, on the special
condition. A problem with the HO2S2 sensor signal will set
DTC P0137, P0138, P0140 or P0141, depending on the
special condition.
A fault in the Rear Heated Oxygen Sensor (HO2S2) heat-
er element or its ignition feed or ground will result in lower
oxygen sensor response. This may cause incorrect cata-
lyst monitor diagnostic results.

1F – 626IENGINE CONTROLS
DAEWOO V–121 BL4
EXHAUST GAS RECIRCULATION
VA LV E
The Exhaust Gas Recirculation (EGR) system is used on
engines equipped with an automatic transaxle to lower
NOx (oxides of nitrogen) emission levels caused by high
combustion temperature. The EGR valve is controlled by
the engine control module (ECM). The EGR valve feeds
small amounts of exhaust gas into the intake manifold to
decrease combustion temperature. The amount of ex-
haust gas recirculated is controlled by variations in vacu-
um and exhaust back pressure. If too much exhaust gas
enters, combustion will not take place. For this reason,
very little exhaust gas is allowed to pass through the valve,
especially at idle.
The EGR valve is usually open under the following condi-
tions:
S Warm engine operation.
S Above idle speed.
Results of Incorrect Operation
Too much EGR flow tends to weaken combustion, causing
the engine to run roughly or to stop. With too much EGR
flow at idle, cruise, or cold operation, any of the following
conditions may occur:
S The engine stops after a cold start.
S The engine stops at idle after deceleration.
S The vehicle surges during cruise.
S Rough idle.
If the EGR valve stays open all the time, the engine may
not idle. Too little or no EGR flow allows combustion tem-
peratures to get too high during acceleration and load con-
ditions. This could cause the following conditions:
S Spark knock (detonation)
S Engine overheating
S Emission test failure
INTAKE AIR TEMPERATURE
SENSOR
The Intake Air Temperature (IAT) sensor is a thermistor,
a resistor which changes value based on the temperature
of the air entering the engine. Low temperature produces
a high resistance (4,500 ohms at –40°F [–40°C]), while
high temperature causes a low resistance (70 ohms at
266°F [130°C]).
The engine control module (ECM) provides 5 volts to the
IAT sensor through a resistor in the ECM and measures
the change in voltage to determine the IAT. The voltage will
be high when the manifold air is cold and low when the air
is hot. The ECM knows the intake IAT by measuring the
voltage.
The IAT sensor is also used to control spark timing when
the manifold air is cold.
A failure in the IAT sensor circuit sets a diagnostic trouble
code P0112 or P0113.
IDLE AIR CONTROL VALVE
Notice : Do not attempt to remove the protective cap to
readjust the stop screw. Misadjustment may result in dam-
age to the Idle Air Control (IAC) valve or to the throttle
body.
The IAC valve is mounted on the throttle body where it
controls the engine idle speed under the command of the
engine control module (ECM). The ECM sends voltage
pulses to the IAC valve motor windings, causing the IAC
valve pintle to move in or out a given distance (a step or
count) for each pulse. The pintle movement controls the
airflow around the throttle valves which, in turn, control the
engine idle speed.
The desired idle speeds for all engine operating conditions
are programmed into the calibration of the ECM. These
programmed engine speeds are based on the coolant
temperature, the park/neutral position switch status, the
vehicle speed, the battery voltage, and the A/C system
pressure (if equipped).
The ECM ”learns” the proper IAC valve positions to
achieve warm, stabilized idle speeds (rpm) desired for the
various conditions (park/neutral or drive, A/C on or off, if
equipped). This information is stored in ECM ”keep alive”
memories. Information is retained after the ignition is
turned OFF. All other IAC valve positioning is calculated
based on these memory values. As a result, engine varia-
tions due to wear and variations in the minimum throttle
valve position (within limits) do not affect engine idle
speeds. This system provides correct idle control under all
conditions. This also means that disconnecting power to
the ECM can result in incorrect idle control or the necessity
to partially press the accelerator when starting until the
ECM relearns idle control.
Engine idle speed is a function of total airflow into the en-
gine based on the IAC valve pintle position, the throttle
valve opening, and the calibrated vacuum loss through ac-
cessories. The minimum throttle valve position is set at the
factory with a stop screw. This setting allows enough air-
flow by the throttle valve to cause the IAC valve pintle to
be positioned a calibrated number of steps (counts) from
the seat during ”controlled” idle operation. The minimum
throttle valve position setting on this engine should not be
considered the ”minimum idle speed,” as on other fuel in-
jected engines. The throttle stop screw is covered with a
plug at the factory following adjustment.
If the IAC valve is suspected as the cause of improper idle
speed, refer to ”Idle Air Control System Check” in this sec-
tion.
MANIFOLD ABSOLUTE PRESSURE
SENSOR
The Manifold Absolute Pressure (MAP) sensor measures
the changes in the intake manifold pressure which result
from engine load and speed changes. It converts these to
a voltage output.

ENGINE CONTROLS 1F – 627
DAEWOO V–121 BL4
A closed throttle on engine coast down produces a rela-
tively low MAP output. MAP is the opposite of vacuum.
When manifold pressure is high, vacuum is low. The MAP
sensor is also used to measure barometric pressure. This
is performed as part of MAP sensor calculations. With the
ignition ON and the engine not running, the engine control
module (ECM) will read the manifold pressure as baromet-
ric pressure and adjust the air/fuel ratio accordingly. This
compensation for altitude allows the system to maintaindriving performance while holding emissions low. The
barometric function will update periodically during steady
driving or under a wide open throttle condition. In the case
of a fault in the barometric portion of the MAP sensor, the
ECM will set to the default value.
A failure in the MAP sensor circuit sets a diagnostic trouble
code P0107 or P0108.
The following tables show the difference between absolute pressure and vacuum related to MAP sensor output, which
appears as the top row of both tables.
MAP
Volts4.94.43.83.32.72.21.71.10.60.30.3
kPa1009080706050403020100
in. Hg29.626.623.720.717.714.811.88.95.92.90
VACUUM
Volts4.94.43.83.32.72.21.71.10.60.30.3
kPa0102030405060708090100
in. Hg02.95.98.911.814.817..720.723.726.729.6
ENGINE CONTROL MODULE
The engine control module (ECM), located inside the pas-
senger kick–panel, is the control center of the fuel injection
system. It constantly looks at the information from various
sensors and controls the systems that affect the vehicle’s
performance. The ECM also performs the diagnostic func-
tions of the system. It can recognize operational problems,
alert the driver through the Malfunction Indicator Lamp
(MIL), and store diagnostic trouble code(s) which identify
problem areas to aid the technician in making repairs.
There are no serviceable parts in the ECM. The calibra-
tions are stored in the ECM in the Programmable Read–
Only Memory (PROM).
The ECM supplies either 5 or 12 volts to power the sensors
or switches. This is done through resistances in the ECM
which are so high in value that a test light will not come on
when connected to the circuit. In some cases, even an or-
dinary shop voltmeter will not give an accurate reading be-
cause its resistance is too low. You must use a digital volt-
meter with a 10 megohm input impedance to get accurate
voltage readings. The ECM controls output circuits such
as the fuel injectors, the idle air control valve, the A/C
clutch relay, etc., by controlling the ground circuit through
transistors or a device called a ”quad–driver.”
FUEL INJECTOR
The Multiport Fuel Injection (MFI) assembly is a solenoid–
operated device controlled by the engine control module
(ECM). It meters pressurized fuel to a single engine cylin-
der. The ECM energizes the fuel injector or the solenoid
to a normally closed ball or pintle valve. This allows fuel toflow into the top of the injector, past the ball or pintle valve,
and through a recessed flow director plate at the injector
outlet.
The director plate has six machined holes that control the
fuel flow, generating a conical spray pattern of finely atom-
ized fuel at the injector tip. Fuel from the tip is directed at
the intake valve, causing it to become further atomized
and vaporized before entering the combustion chamber.
A fuel injector which is stuck partially open will cause a loss
of fuel pressure after the engine is shut down. Also, an ex-
tended crank time will be noticed on some engines. Diesel-
ing can also occur because some fuel can be delivered to
the engine after the ignition is turned OFF.
KNOCK SENSOR
The knock sensor detects abnormal knocking in the en-
gine. The sensor is mounted in the engine block near the
cylinders. The sensor produces an AC output voltage
which increases with the severity of the knock. This signal
is sent to the engine control module (ECM). The ECM then
adjusts the ignition timing to reduce the spark knock.
ROUGH ROAD SENSOR
The engine control module (ECM) receives rough road in-
formation from the VR sensor. The ECM uses the rough
road information to enable or disable the misfire diagnos-
tic. The misfire diagnostic can be greatly affected by
crankshaft speed variations caused by driving on rough
road surfaces. The VR sensor generates rough road infor-
mation by producing a signal which is proportional to the
movement of a small metal bar inside the sensor.
If a fault occurs which causes the ECM to not receive
rough road information between 30 and 80 mph (50 and
132 km/h), DTC P1391 will set.

SECTION : 4C
POWER BOOSTER
TABLE OF CONTENTS
SPECIFICATIONS4C–1 . . . . . . . . . . . . . . . . . . . . . . . . . .
Fasrener Tightening Specifications 4C–1. . . . . . . . . .
DIAGNOSIS4C–1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Booster Functional Check 4C–1. . . . . . . . . . . .
MAINTENANCE AND REPAIR4C–2 . . . . . . . . . . . . . . . ON–VEHICLE SERVICE 4C–2. . . . . . . . . . . . . . . . . . . . .
Vacuum Hose 4C–2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Booster Assembly 4C–2. . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION4C–6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Booster 4C–6. . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPECIFICATIONS
FASRENER TIGHTENING SPECIFICATIONS
ApplicationNSmLb–FtLb–In
Booster–to–Bracket Nuts (Right–Hand Drive)2216–
Booster–to–Dash Panel Nut (Left–Hand
Drive)2216–
Booster Hex Nut and Pushrod Clevis1813–
Brake Line Fittings1612–
DIAGNOSIS
POWER BOOSTER FUNCTIONAL
CHECK
1. With the engine stopped, eliminate vacuum in the
booster by pumping the brake pedal several times.
2. Push the pedal down and hold in this position.
3. Start the engine.4. The booster is OK if the pedal drops further be-
cause of extra force produced.
If the brake pedal does not drop, the vacuum system (vac-
uum hoses, check valve, etc.) is probably defective and
should be checked.
If no defect is revealed by checking the vacuum system,
the defect is in the booster itself.

4C – 6IPOWER BOOSTER
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
POWER BOOSTER
This booster is a single or tandem diaphragm, vacuum–
suspended unit. In a normal operating mode, with the ser-
vice brakes in the release position, a vacuum–suspended
booster operates with a vacuum on both sides of its dia-phragm. When the brakes are applied, air at atmospheric
pressure is admitted to one side of the diaphragm to pro–
vide the power assist. When the brakes are released, at-
mospheric air is shut off from that side of the dia–phragm.
The air is then drawn from the booster through the vacuum
check valve by the vacuum source.
Important : If any hydraulic component is removed or dis-
connected, it may be necessary to bleed all or part of the
brake system.

5A1 – 50IZF 4 HP 16 AUTOMATIC TRANSAXLE
DAEWOO V–121 BL4
TCC shudder should only occur during the APPLY and/or
RELEASE of the Lock up clutch.
While TCC Is Applying Or Releasing
If the shudder occurs while TCC is applying, the problem
can be within the transaxle or torque converter.
Something is not allowing the clutch to become fully en-
gaged, not allowing clutch to release, or is trying to release
and apply the clutch at the same time. This could be
caused by leaking turbine shaft seals, a restricted release
orifice, a distorted clutch or housing surface due to long
converter bolts, or defective friction material on the TCC
plate.
Shudder Occurs After TCC Has Applied :
In this case, most of the time there is nothing wrong with
the transaxle! As mentioned above, once the TCC has
been applied, it is very unlikely that will slip. Engine prob-
lems may go unnoticed under light throttle and load, but
become noticeable after TCC apply when going up a hill
or accelerating, due to the mechanical coupling between
engine and transaxle.
Important : Once TCC is applied there is no torque con-
verter assistance. Engine or driveline vibrations could be
unnoticeable before TCC engagement.
Inspect the following components to avoid misdiagnosis of
TCC shudder and possibly disassembling a transaxle and/
or replacing a torque converter unnecessarily :
S Spark plugs – Inspect for cracks, high resistance or
broken insulator.
S Plug wires – Lock in each end, if there is red dust
(ozone) or black substance (carbon) present, then
the wires are bad. Also look for a white discolor-
ation of the wire indicating arcing during hard accel-
eration.
S Distributor cap and rotor – look for broken or un–
crimped parts.
S Coil – look for black on bottom indication arcing
while engine is misfiring.
S Fuel injector – filter may be plugged.
S Vacuum leak – engine won’t get correct amount of
fuel. May run rich or lean depending on where the
leak is.S EGR valve – valve may let it too much unburnable
exhaust gas and cause engine to run lean.
S MAP sensor – like vacuum leak, engine won’t get
correct amount of fuel for proper engine operation.
S Carbon on intake valves – restricts proper flow or
air/fuel mixture into cylinders.
S Flat cam – valves don’t open enough to let proper
fuel/air mixture into cylinders.
S Oxygen sensor – may command engine too rich or
too lean for too long.
S Fuel pressure – may be too low.
S Engine mounts – vibration of mounts can be multi-
plied by TCC engagement.
S Axle joints – checks for vibration.
S TPS – TCC apply and release depends on the TPS
in many engines. If TPS is out of specification, TCC
may remain applied during initial engine starting.
S Cylinder balance – bad piston rings or poorly seal-
ing valves can cause low power in a cylinder.
S Fuel contamination – causes poor engine perfor-
mance.
TCM INITIALIZATION PROCEDURE
When one or more operations such as shown below are
performed, all learned contents which are stored in TCM
memory should be erased after the operations.
S When A/T H/W is replaced in a vehicle,
S When a used TCU is installed in other vehicle,
S When a vehicle condition is unstable (engine RPM
flare, TPS toggling and so on; at this kind of unsta-
ble conditions, mis–adaptation might be done).
1. Connect the Scan 100 with a DLC connector in a
vehicle.
2. Turn ignition switch ON.
3. Turn the power on for the Scan 100.
4. Follow the ”TCM LEARNED INITIALIZE” procedure
on the Scan 100 menu.
Notice : Before pushing ”Yes” Button for TCM initialization
on the Scan 100 screen, make sure that the condition is
as follows:
Condition :
1. Engine idle.
2. Select lever set ”P” range.

7B – 16IMANUAL CONTROL HEATING, VENTILATION AND AIR CONDITIONING SYSTEM
DAEWOO V–121 BL4
SYMPTOM DIAGNOSIS
PRESSURE TEST CHART (R–134A SYSTEM)
Test ResultsRelated SymptiomsProbable CauseRemedy
Discharge (high)
pressure abnormally
highAfter stopping the compres-
sor, the pressure drops
about 299 kPa (28 psig)
quickly, then falls gradually.Air in the system.Recover, evacuate and re-
charge the system with the
specified amount of refrig-
erant.
The condenser is exces-
sively hot.Excessive refrigerant in the sys-
tem.Recover, evacuate and re-
charge the system with the
specified amount of refrig-
erant.
Reduced or no airflow
through the condenser.Condenser or the radiator fins are
clogged.Clean the condenser or the
radiator fins.
Condenser or the radiator fan is
not working properly.Check the voltage and the
fan rpm.
Check the fan direction.
Line to the condenser is ex-
cessively hot.Restricted flow of refrigerant in
the system.Locate and repair the re-
striction.
Discharge pressure
abnormally lowThe condenser is not hot.Insufficient refrigerant in the sys-
tem.Check the system for a
leak.
Charge the system.
High and low pressures are
balanced soon after stop-
ping the compressor.Faulty compressor pressure relief
valve.Repair or replace the com-
pressor.
Low–side pressure is high-
er than normal.Faulty compressor seal.
The outlet of the expansion
valve is not frosted.Faulty expansion valve.Replace the expansion
valve.
Low pressure gauge indi-
cates vacuum.Moisture in the system.Recover, evacuate, and re-
charge the system.
Suction (low) pres-
sure abnormally lowCondenser is not hot.Insufficient refrigerant in the sys-
tem.Repair the leaks.
Recover, evacuate, and re-
charge the system.
The expansion valve is not
frosted and the lowpressure
line is not cold.Faulty expansion valve.Replace the expansion
valve.
Low–Pressure gauge indi-
cates a vacuum.Frozen expansion valve.
Discharge temperature is
low and the airflow from the
vents is restricted.Evaporator is frozen.Clear the restricted evapo-
rator case drain.
The expansion valve is
frosted.Expansion valve is clogged.Clean or replace the expan-
sion valve.
The receiver–dryer outlet is
cool and the inlet is warm.Receiver–dryer is clogged.Replace the receiver–dryer.
Suction pressure ab-
normally highLow–pressure hose and
check joint are cooler than
the temperature around the
evaporator.Expansion valve is opened for too
long.Replace the expansion
valve.
Capillary tube is loose.

7B – 20IMANUAL CONTROL HEATING, VENTILATION AND AIR CONDITIONING SYSTEM
DAEWOO V–121 BL4
S Dip new O–rings in clean polyalkaline glycol refrig-
erant oil before installation.
MAINTAINING CHEMICAL STABILITY
IN THE REFRIGERATION SYSTEM
The efficient operation and the life of the air conditioning
(A/C) system is dependent upon the chemical stability of
the refrigeration system. When foreign materials, such as
dirt, air, or moisture, contaminate the refrigeration system,
they will change the stability of the refrigerant and the poly-
alkaline glycol (PAG) compressor oil. They will also affect
the pressure–temperature relationship, reduce efficient
operation, and can possibly cause interior corrosion and
abnormal wear of moving parts.
Observe the following practices to ensure chemical stabil-
ity in the system:
S Wipe away dirt or oil at and near any connection
before opening that connection. This will reduce the
chance of dirt entering the system.
S Cap, plug, or tape both sides of a connection as
soon as possible after opening the connection. This
will prevent the entry of dirt, foreign material, and
moisture.
S Keep all tools clean and dry, including the manifold
gauge set and all replacement parts.
S Use a clean and dry transfer device and container
to add polyalkaline glycol refrigerant oil. This will
ensure that the oil remains as moisture–free as
possible. Refer to ”Discharging, Adding Oil, Eva-
cuating, and Charging Procedures for A/C System”
in this section.
S Have everything you need ready to allow you to
perform all operations quickly when opening an A/C
system. Do not leave the A/C system open any lon-
ger than necessary.
S Evacuate and recharge any A/C system that has
been opened. Refer to ”Discharging, Adding Oil,
Evacuating, and Charging Procedures for A/C Sys-
tem” in this section for the instructions to perform
this procedure properly.
All service parts are dehydrated and sealed before ship-
ping. They should remain sealed until just before making
connections. All the parts should be at room temperature
before uncapping. This prevents condensation of mois-
ture from the air from entering the system. Reseal all parts
as soon as possible.
DISCHARGING, ADDING OIL,
EVACUATING, AND CHARGING
PROCEDURES FOR A/C SYSTEM
CAUTION : Use only refillable refrigerant tanks that
are authorized for the charging station being used.
The use of other tanks may cause personal injury or
void the warranty. Refer to the manufacturer’s in-
structions for the charging station.CAUTION : To avoid personal injury, always wear
goggles and gloves when performing work that in-
volves opening the refrigeration system.
A charging station discharges, evacuates, and recharges
an air–conditioning (A/C) system with one hookup. Filter-
ing the refrigerant during the recovery cycle together with
filtering during the evacuation cycle ensures a supply of
clean, dry refrigerant for A/C system charging.
S Never use the R–134a charging station on a sys-
tem charged with R–12. The refrigerants and the
oils from each system are not compatible with
those from the other system and must never be
mixed, even in the smallest amount. Mixing refriger-
ant residue will damage the equipment.
S Never use adapters which convert from one size
fitting to another. Such use allows contamination,
which may cause system failure.
Charging Station Setup and Maintenance
There are many charging stations available. All perform
the various tasks required to discharge the system and re-
cover refrigerant, evacuate the system, add a measured
amount of oil, and recharge an A/C system with a mea-
sured amount of refrigerant. Refer to the manufacturer’s
instructions for all initial setup procedures and all mainte-
nance procedures.
Control Panel Functions
A charging station will have controls and indicators to allow
the operator to control and monitor the operation in prog-
ress. Refer to the manufacturer’s instructions for details.
These can be expected to include the following:
1. Main Power Switch
S Supplies electrical power to the control panel.
2. Display
S Shows the time programmed for vacuum.
S Shows the weight of the refrigerant programmed
for recharging.
S Refer to the manufacturer’s instructions for de-
tailed programming information.
3. Low–Side Manifold Gauge
S Shows the system’s low–side pressure.
4. High–Side Manifold Gauge
S Shows the system’s high–side pressure.
5. Controls Panel
S Controls the various operating functions.
6. Low–Side Valve
S Connects the low side of the A/C system to the
unit.
7. Moisture Indicator
S Shows whether the refrigerant is wet or dry.
8. High–Side Valve
S Connects the high side of the A/C system to the
unit.