2003 DAEWOO MATIZ low oil pressure

7B–2 MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
SYSTEM COMPONENTS
–FUNCTIONAL
Compressor
All compressors are belt–driven from the engine crank-
shaft through the compressor clutch pulley. The com-
pressor pulley rotates without driving the compressor
shaft until on electromagnetic clutch coils energized.
When voltage is applied to energize the clutch coil, the
clutch plate and hub assembly are drawn toward the
pulley. The magnetic force locks the clutch plate and
pulley together as one unit to drive the compressor
shaft.
Condenser Core
The condenser assembly in front of the radiator consists
of coils which carry the refrigerant and cooling fins that
provide the rapid transfer of heat. The air passing
through the condenser cools the high–pressure refriger-
ant vapor and cause it to condense into a liquid.
Expansion Valve
The expansion valve is located on the passenger
compartment side of the dash panel. The expansion
valve can fail in three different positions: open, closed,
or restricted. An expansion valve that fails in the open
position will result in a noisy A/C compressor or no cool-
ing. The cause can be a broken spring, a broken ball, or
excessive moisture in the A/C system. If the spring or
the ball is found to be detective, replace the expansion
valve. If excessive moisture is found in the A/C system,
recycle the refrigerant. An expansion valve that fails in
the closed position will result in low suction pressure and
no cooling. This may be caused by a failed power done
or excessive moisture in the A/C system. If the power
dome on the expansion valve is found to be defective,
replace the expansion valve. If excessive moisture is
found in the A/C system, recycle the refrigerant.
A restricted expansion valve will result in low suction
pressure and no cooling. This may be caused by debrisin the refrigerant system. If debris is believed to be
cause, recycle the refrigerant, replace the expansion
valve, and replace the receiver/dryer.
Evaporator Core
The evaporator is device which cools and dehumidifies
the air before it enters the vehicle. High–pressure liquid
refrigerant flows through the expansion tube (orifice)
and becomes a low–pressure gas in the evaporator. The
heat in the air passing through the evaporator core is
transferred to the cooler surface of the core, which cools
the air. As the process of heat transfer from the air to the
evaporator core surface is taking place, any moisture
(humidity) in the air condenses on the outside surface of
the evaporator core and is drained off as water.
Receiver–Dryer
The sealed receiver–dryer assembly is connected to the
evaporator outlet pipe. It acts as a refrigerant storing
container, receiving liquid and some vapor and refriger-
ant oil from the evaporator.
At the bottom the receiver–dryer is the desiccant, which
acts as a drying agent for the moisture that may have
entered the system. The receiver–dryer is serviceable
only as an assembly.
Dual Cut Switch
The dual cut switch controls compressor operation when
the cycling refrigerant pressure is dropped or surged.
Evaporator Thermistor
A semiconductor which resistance is noticeably changed
as the change of temperature. When the refrigerant tem-
perature of the evaporator drops to 0
C (32
F) and be-
low, the evaporator cores get stuck with frost or ice,
reducing the airflow, lowering the cooling capacity. The
thermistor is a sensor which is used to prevent from frost-
ing or icing.
The thermistor is installed on the evaporator.

7B–6 MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO M-150 BL2
PRESSURE-TEMPERATURE RELATIONSHIP OF R-134A


TEMPERATURE

C (
F)*

PRESSURE
kPa (psig)*

TEMPERATURE

C (
F)*

PRESSURE
kPa (psig)*
–8.89 (16) 105.70 (15.33) 37.78 (100) 856.84 (124.27)
–7.78 (18) 114.87 (16.66) 38.89 (102) 886.56 (128.58)
–6.67 (20) 124.32 (18.03) 40.00 (104) 916.35 (132.98)
–5.56 (22) 134.11 (19.45) 41.11 (106) 947.92 (137.48)
–4.44 (24) 144.24 (20.92) 42.22 (108) 979.64 (142.08) –3.33 (26) 154.65 (22.43) 43.33 (110) 1012.11 (146.79) –2.22 (28) 165.48 (24.00) 44.44 (112) 1045.21 (151.59)
–1.11 (30)

176.65 (25.62)

45.56 (114)

1079.14 (156.51)
0.00 (32) 188.16 (27.29) 46.67 (116) 1113.75 (161.53)
1.11 (34) 200.02 (29.01) 47.78 (118) 1149.12 (166.66)
2.22 (36) 212.30 (30.79) 48.89 (120) 1185.18 (171.89)
3.33 (38) 224.98 (32.63) 50.00 (122) 1222.07 (177.24)
4.44 (40) 238.08 (34.53) 51.11 (124) 1259.72 (182.70)
7.22 (45) 272.49 (39.52) 52.22 (126) 1298.12 (188.27)
10.00 (50) 309.58 (44.90) 53.33 (128) 1337.35 (193.96) 12.77 (55) 349.51 (50.69) 54.44 (130) 1377.35 (199.76) 15.56 (60) 392.33 (56.90) 57.22 (135) 1480.91 (214.78)
18.33 (65)

438.18 (63.55)

60.00 (140)

1589.57 (230.54)
21.11 (70) 487.27 (70.67) 62.78 (145) 1703.62 (247.08)
23.89 (75) 539.67 (78.27) 65.56 (150) 1823.04 (264.40)
26.67 (80) 609.38 (88.38) 68.33 (155) 1948.04 (282.53)
29.44 (85) 655.09 (95.01) 71.11 (160) 2078.77 (301.49)
32.22 (90) 718.39 (104.19) 73.89 (165) 2215.29 (321.29)
35.00 (95) 785.61 (113.94) 76.67 (170) 2357.81 (341.96)
* All values rounded to two decimal places.
EVAPORATOR RANGE: From –6.67 to 7.22
C (20 to 45
F), the temperatures represent the gas temperatures inside
the coil and not on the coil surfaces. Add 1.67 to 5.56
C (3 to 10
F) the temperature for coil and air-off temperatures.
CONDENSER RANGE: From 110 to 160
F, temperatures are not ambient. Add 19.4 to 22.2
C (35 to 40
F) for proper
heat transfer, then refer to the pressure chart.
Example: 32
C (90
F) ambient temperature
+22

C (40
F)
54
C (130
F)
Condenser temperature = 1379 kPa (200 psig)
Based on 48.3 km/h (30 mph) air flow.

7B–8 MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO M-150 BL2
AIR CONDITIONING SYSTEM DIAGNOSIS
INSUFFICIENT COOLING DIAGNOSIS
Step Action Value(s) Yes No
1Can you verify the customer complaint?–Go to Step 2System OK
2
1. Check the fuses Ef14, Ef19, and Ef12.
2. Check the blower fan operation.
3. Check the engine cooling fan operation.
4. Check the A/C compressor belt.
5. Check the A/C condenser for restricted air flow.
6. Check the slippage of the compressor clutch.
7. Repair or replace any components as needed.
8. Check the A/C system operation.
Is the A/C system operation normal?
–
System OKGo to Step 3
3
1. Turn the ignition switch OFF.
2. Connect the high and the low pressure gauges.
Are both pressures within the value specified?
Low SideGo to Step 8Go to Step 6
4Are both pressures above the specified value?Pressure:Go to Step 5–
5Are both pressures within the specified value?200 kPa
(29 Psi)Go to Step 8–
6Are both pressure below the specified value?
(29 Psi)
Go to Step 7Go to Step 4
7
1. Add the refrigerant R–134a.
2. Check the A/C system for leaks.
3. Repair any refrigerant leaks as needed.
4. Recover, evacuate, and recharge the A/C system.
Are both pressure within the specified value?High Side
Pressure:
1,500 kPa
(217.5 Psi)
Go to Step 8
–
8
1. Start the engine and allow it to run at idle.
2. Set the A/C controls to following positions.
The A/C switch to the ON position.
The fresh air control switch to fresh air.
The blower motor to 4.
The temperature to full cold.
Does the A/C compressor clutch engage?
–
Go to Step 9Go to Step 11
9
1. Check for a knocking noise from the A/C
compressor.
2. Cycle the A/C compressor ON and OFF in order
to verify the source of the noise.
Do you hear a loud knocking noise?
–
Go to Step 10Go to Step 14
10
1. Recover the A/C system refrigerant.
2. Replace the A/C compressor.
3. Evacuate and recharge the A/C system.
4. Check the A/C system for leaks.
Is the repair complete?
–
Go to Step 14
–
11
1. Turn the ignition switch OFF.
2. Disconnect the A/C compressor clutch coil
connector.
3. Connect a jumper wire from ground to one A/C
compressor clutch coil terminal.
4. Connect a fused jumper wire from the positive
battery terminal to the other A/C compressor
clutch coil terminal.
Does the A/C clutch engage?
–
Go to Step 12Go to Step 13

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7B–9
DAEWOO M-150 BL2
Insufficient Cooling Diagnosis (Cont’d)
Step Action Value(s) Yes No
12
Repair the electrical circuit to the A/C compressor
clutch coil.
Does the A/C clutch engage?
–
Go to Step 20Go to Step 13
13Replace the A/C compressor clutch coil.
Does the A/C clutch engage?–Go to Step 9Go to Step 10
14
Important: Perform this test under garage condi-
tions; 21-32
C (70-90
F) and no sun load. Follow
this test carefully for accurate results.
1. Close all of the windows and the doors of the
vehicle.
2. Set the A/C controls to the following positions:
The A/C switch to the ON position.
The fresh air control switch to fresh air.
The blower motor to 4.
The temperature to full cold.
3. Start the engine and follow it to run at idle for
5 minutes.
4. Feel the evaporator inlet and outlet pipes.
Is there a noticeable difference in the temperature of
the evaporator inlet and outlet pipes?
–
Go to Step 16Go to Step 15
15
1. Recover the A/C system refrigerant.
2. Replace the expansion valve as needed.
3. Evacuate and recharge the A/C system.
4. Check the A/C system for leaks.
5. Note the discharge air temperature with the A/C
ON.
Is the discharge temperature normal?
–
Go to Step16Go to Step 18
16
Feel the liquid pipe between the condenser and the
expansion valve.
Is the pipe cold?
–
Go to Step 19Go to Step 17
17
1. Remove the restriction of the high pressure side.
2. Check the A/C system for leaks.
Is the repair complete?
–
System OK
–
18
1. Recover the A/C system refrigerant.
2. Evacuate and recharge the A/C system.
3. Check the A/C system for leaks.
Is the repair complete?
–
System OK
–
19
1. Run the engine at 3,000 rpm.
2. Close all of the windows and doors of the vehicle.
3. Set the A/C controls to the following positions:
The A/C switch to the ON position.
The fresh air control switch to fresh air.
The blower motor to 4.
The temperature to full cold.
4. Turn the A/C switch ON and OFF every
20 seconds for 3 minutes.
Are the A/C compressor high and the low side
pressures within the specified value of each other?
Low Side
Pressure:
200 kPa
(29 psi)
High Side
Pressure:
1,500 kPa
(217.5 psi)
System OKGo to Step 22

7B–12 MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO M-150 BL2
Pressure Test Chart (R-134a System) (Cont’d)
Condition Related Symptons Probable Cause Correction

Suction Pressure
Abnormally High
Low pressure hose and
check joint are cooler
The expansion valve is
opened for too long.
Replace the expansion
valve.

Abnormally High

check joint are cooler
than the temperature
around the evaporator.

opened for too long.

valve.








Suction pressure is
lowered when the con-
denser is cooled by
water.



There is excessive
refrigerant in the system.



Recover, evacuate, and
recharge the system.
Suction and Dis-
charge Pressure Reduced airflow
through the condenser. The condenser or the
radiator fins are clogged. Clean the condenser and
the radiator.




Abnormally High







The radiator cooling fans
are not working properly.




Check the voltage and
the radiator cooling fan
rpm.
Check the fan direction.




Condenser is
excessively hot.

There is excessive
refrigerant in the system.

Recover, evacuate, and
recharge the system.



Suction and Dis-
charge Pressure
Abnormally Low


Low pressure hose and
metal end areas are
cooler than the
evaporator.


Clogged or kinked low
pressure hose.


Repair or replace the low
pressure hose.








Temperature around the
expansion valve is low
compared to that
around the
receiver/drier.



The high pressure line is
clogged.



Repair or replace the
high pressure line.


Refrigerant Leaks

The compressor clutch
is dirty.

The compressor shaft seal
is leaking.

Repair or replace the
compressor.
The compressor bolts
are dirty. Leaking around a
compressor housing bolt. Tighten the bolt(s) or
replace the compressor.



The compressor gasket
is wet with oil.

The compressor gasket is
leaking.

Repair or replace the
compressor.



–

Poor tightening in the
system.
Retighten the connection
(coupling, bolt etc.)
– O–ring is faulty. Replace the O–ring.

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7B–13
DAEWOO M-150 BL2
REPAIR INSTRUCTIONS
ON-VEHICLE SERVICE
GENERAL A/C SYSTEM
SERVICE PROCEDURES
O-RING REPLACEMENT
Important: Even though O-rings may look identical, it is
extremely important that only recommended service re-
placement air conditioning O-rings be used, or exces-
sive leakage of refrigerant may occur.
Important: Always slip the O-ring onto the flange tube
to ensure proper locating and sealing.
Install new DAEWOO-approved service replacement air
conditioning O-rings whenever a joint or a fitting is disas-
sembled, except when the O-rings are provided on new
components.
When replacing O-rings on an air conditioning compo-
nent or a joint connection, the fitting design should be
identified to ensure installation of the correct air condi-
tioning service replacement O-ring.
Before installation, verify that both O-rings and fittings
have not been nicked or deformed. Deformed or nicked
parts must be replaced. Failure to use the proper service
replacement parts and procedures may result in exces-
sive refrigerant leakage.
HANDLING REFRIGERANT
Caution: Always work in a well-ventilated area and
avoid breathing any refrigerant fumes. If you have
difficulty breathing, seek medical attention immedi-
ately. If refrigerant comes in contact with any part of
your body, flush the exposed area with water. If a
rash or pain develops, seek medical attention.
Air conditioning systems contain refrigerant. This is a
chemical mixture which requires special handling proce-
dures to avoid personal injury.
Always wear goggles and wrap a clean cloth around the
fittings, the valves and the connections when performing
work that involves opening the refrigerant system. Do
not weld or steam clean on or near any vehicle-installed
air conditioning lines or components.
All refrigerant drums are shipped with a heavy metal
screw cap. The purpose of the cap is to protect the valve
and the safety plug from damage. It is good practice to
replace the cap after each use of the drum.
If it is necessary to transport or carry any container of
refrigerant in a vehicle, do not carry it in the passenger
compartment.
HANDLING OF REFRIGERANT LINES
AND FITTINGS
Notice: Using too low or too high torque when tightening
a fitting can result in loose joints or deformed joint parts.
Both conditions can result in refrigerant leakage.
Keep all metal tubing lines free of dents or kinks. Any
line restrictions will cause the loss of system capacity.
Never bend a flexible hose line to a radius of less than
four times the diameter of the hose.
Never allow a flexible hose line to come near the ex-
haust manifold.
Inspect flexible hose lines regularly for leaks or brittle-
ness.
Replace flexible hose lines with new lines if you find
signs of deterioration or leaking.
Discharge the refrigeration system of all refrigerant
before disconnecting any fitting in the refrigeration
system.
Proceed very cautiously regardless of the gauge
readings.
Open the fittings very slowly.
Keep your face and your hands away from the fitting
so that you will not be injured if there happens to be
liquid refrigerant in the line.
If you notice pressure when you loosen a fitting, allow
the pressure to bleed off as described under “Dis-
charging, Adding Oil, Evacuating and Charging Pro-
cedures for A/C System” in this section.
Cap or tape any refrigerant line immediately after it is
opened. This will prevent the entrance of moisture
and dirt, which can cause internal compressor wear
or plugged lines in the condenser, the evaporator
core, the expansion valve or the compressor inlet
screens.
Important: Use two proper wrenches to connect the O-
ring fittings.
Back up the opposing fitting to prevent distortion of
the connecting lines or the components.
Back up both the swaged fitting on the flexible hose
connections and the coupling to which it is attached
with two wrenches to prevent turning the fitting and
damaging the ground seat.
Keep the O-rings and the seats in perfect condition. A
burr or a piece of dirt may cause a refrigerant leak.
Dip new O-rings in clean PAG refrigerant oil before
installation.

7B–14 MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM
DAEWOO M-150 BL2
MAINTAINING CHEMICAL STABILITY
IN THE REFRIGERATION SYSTEM
The efficient operation and life of the air conditioning
system is dependent upon the chemical stability of the
refrigeration system. When foreign materials, such as
dirt, air, or moisture, contaminate the refrigeration sys-
tem, they will change the stability of the refrigerant and
the PAG compressor oil. They will also affect the pres-
sure-temperature relationship, reduce efficient opera-
tion, and can possibly cause interior corrosion and
abnormal wear of moving parts.
Observe the following practices to ensure chemical sta-
bility in the system:
Wipe away dirt or oil at and near any connection be-
fore opening that connection. This will reduce the
chance of dirt entering the system.
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 mois-
ture.
Keep all tools clean and dry, including the manifold
gauge set and all replacement parts.
Use a clean and dry transfer device and container to
add PAG refrigerant oil. This will ensure that the oil
remains as moisture-free as possible. Refer to “Dis-
charging, Adding Oil, Evacuating and Charging Pro-
cedures for A/C System” in this section.
Have everything you need ready to allow you to per-
form all operations quickly when opening an A/C sys-
tem. Do not leave the A/C system open any longer
than necessary.
Evacuate and recharge any A/C system that has
been opened. Refer to “Discharging, Adding Oil, Eva-
cuating and Charging Procedures for A/C System” in
this section for the instructions to perform this proce-
dure 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 tempera-
ture before uncapping. This prevents condensation of
moisture from the air from entering the system. Reseal
all parts as soon as possible if the caps have been re-
moved but the connections cannot be made promptly.
DISCHARGING, ADDING OIL,
EVACUATING, AND CHARGING
PROCEDURES FOR A/C SYSTEMS
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 re-
charges an air conditioning system with one hook-up.
Filtering during the recovery cycle together with filtering
during the evacuation cycle ensures a supply of clean,
dry refrigerant for A/C system charging.
Notice:
Never use the R-134a charging station on a system
charged with R-12. The refrigerants and the oils are
not compatible and must never be mixed in even the
smallest amount. Mixing refrigerant residue will dam-
age the equipment.
Never use adapters which convert from one size fit-
ting to another. This will allow contamination which
may cause system failure.
Charging Station Setup and Maintenance
Refer to the manufacturer’s instructions for all initial set-
up procedures and all maintenance procedures. 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 air conditioning system
with a measured amount of refrigerant.
Control Panel Functions
A charging station will have controls and indicators to al-
low the operator to control and monitor the operation in
progress. Refer to the manufacturer’s instructions for
details. These can be expected to include:
1. Main Power Switch: The main power switch supplies
electrical power to the control panel.
2. Display: The display shows the time programmed for
vacuum and the weight of the refrigerant pro-
grammed for recharging. Refer to the manufacturer’s
instructions for detailed programming information.
3. Low Side Manifold Gauge: This gauge shows the
system’s low side pressure.
4. High Side Manifold Gauge: This gauge shows the
system’s high side pressure.
5. Controls: This will contain the controls that control
various operating functions.
6. Low Side Valve: This valve connects the low side of
the A/C system to the unit.
7. Moisture Indicator: This indicator shows if the refrig-
erant is wet or dry.
8. High Side Valve: This valve connects the high side of
the A/C system to the unit.

MANUAL CONTROL HEATING, VENTILATION, AND AIR CONDITIONING SYSTEM 7B–15
DAEWOO M-150 BL2
Refrigerant Recovery
Important: Use only a refrigerant tank that is designed
for the charging station in use. The unit’s overfill limita-
tion mechanism is calibrated specifically for use with this
tank. The tank’s valves are also specifically for this unit.
1. Attach the high side hose with the quick disconnect
coupler to the high side fitting of the vehicle’s A/C
system.
2. Open the coupler valve after attachment.
3. Attach the low side hose with the quick disconnect
coupler to the low side fitting of the vehicle’s A/C
system.
4. Open the coupler valve after attachment.
5. Check the high side and the low side gauges on the
unit’s control panel in order to ensure that the A/C
system has pressure. If there is no pressure, there
is no refrigerant in the system to recover.
Important: If there is no refrigerant in the system, do
not continue with the recovery operation. This will draw
air into the recovery tank.
6. Open both the high side and the low side valves.
7. Open the gas and the liquid valves on the tank.
8. Drain any oil that may be in the oil separator.
9. Close the oil drain valve.
10. Plug the unit into the proper voltage outlet.
11. Turn on the main power switch.
Notice: Never reuse refrigerant oil. Damage to the A/C
system may result. Dispose of the refrigerant oil proper-
ly.
12. Begin the recovery process. Refer to the manufac-
turer’s instructions for the charging station in use.
Important: Some A/C system PAG lubricating oil may
be removed with the refrigerant during recovery. The
amount of oil removed varies. A charging station sepa-
rates the oil from the refrigerant and allows a means of
determining how much oil was removed. Replace the
same amount of oil when you recharge the system. Re-
fer to the manufacturer’s instructions for the charging
station in use.
13. Wait 5 minutes. Check the control panel low side
gauge. If the A/C has maintained vacuum, the re-
covery is complete.
14. There is more refrigerant in the system if the low
side gauge pressure rises above zero. Recover the
additional refrigerant. Repeat this step until the sys-
tem maintains vacuum for two minutes.
Important: If the control indicator shows that the refrig-
erant tank is full during the recovery process and the unit
shuts off, install an empty unit tank to store the refriger-
ant needed for steps later in the procedure. Do not use
any other type of tank.
Evacuation
The unit tank must contain a sufficient amount of R-134a
refrigerant for charging. Check the amount of refrigerant
in the tank. If there is less than 3.6 kg (8 pounds) of re-
frigerant, add new refrigerant to the tank. Refer to the
manufacturer’s instructions for adding refrigerant.
1. Verify that the high side and the low side hoses are
connected to the A/C system. Open both the high
side and the low side valves on the unit’s control pan-
el.
2. Open both the gas and the liquid valves on the tank.
Important: Refer to the manufacturer’s instructions for
the charging station in use. It is necessary to evacuate
the system before recharging it with new or recycled re-
frigerant.
3. Start the vacuum pump and begin the evacuation
process. Non-condensable gases (mostly air) are au-
tomatically vented from the tank during the recycling
process. You may hear the pressure being released.
4. Check for leaks in the system. Refer to the manufac-
turer’s instructions for the charging station in use.
Important:
Change the vacuum pump oil frequently. Refer to the
manufacturer’s instructions for the charging station in
use.
A/C System Oil Charge Replenishing
Any oil removed from the A/C system during the recov-
ery process must be replenished at this time.
1. Use the correct graduated bottle of polyalkaline glycol
(PAG) oil for the R-134a system.
Important:
Keep the oil bottles tightly capped at all times to pro-
tect the oil from moisture and contamination.
Never open the oil injection valve while there is posi-
tive pressure in the A/C system. This will result in oil
blow-back through the bottle vent. You must have
A/C system vacuum for this operation.
Never let the oil level drop below the pick-up tube
while charging or replenishing the system. This will
allow air into the A/C system.
2. Refer to the manufacturer’s instructions for the charg-
ing station in use. Add the proper amount of PAG oil
to the system.
3. Close the valve when the required oil charge has
been pulled into the system.
Charging
Important: Evacuate the air conditioning system before
charging.
1. Close the low side valve on the control panel.
2. Open the high side valve on the control panel.