Mitsubishi CITY MULTI PUD-P250YMF-C How to use

AIR CONDITIONERS CITY MULTI
Models < Outdoor unit >
PUD-P250YMF-C
< Iutdoor unit >
PFD-P250VM-A
PFD-P500VM-A
Service Handbook
Service Handbook PUD-P250YMF-C
PFD-P250VM-A
PFD-P500VM-A
Issued in Jun. 2004 MEE03K207-A
Printed in Japan
New publication effective Jun. 2004
Specifications subject to change without notice.
HEAD OFFICE: MITSUBISHI DENKI BLDG., 2-2-3, MARUNOUCHI, CHIYODA-KU, TOKYO 100-8310, JAPAN
Service Handbook Close Control PUD-P250YMF-C/PFD-P250, P500VM-A

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Contents
Please Read Before Servicing the Unit
1Check Before Servicing the Unit .................................................. 8
[1] Find out the model type and refrigerant type of the unit to be serviced .. 8
[2] Principal System Components .............................................. 8
[3] Check the symptoms of the unit requiring service ................ 9
[4] Be sure to read Read Before Servicing at the beginning of this manual .. 9
[5] Prepare necessary tools ........................................................ 9
[6] If the refrigerant circuit is opened (to repair gas leak etc.),
the drier needs to be replaced .............................................. 9
[7] Preparing the connecting pipes: When relocating or replacing
the unit, find out what types of refrigerant is used for the unit .... 9
[8] If there is a gas leak or if the remaining refrigerant is exposed to an open flame,
a noxious gas hydrofluoric acid may form. Provide adequate ventilation .......... 9
2Necessary Tools and Materials .................................................... 10
[1] List of Tools and Materials Necessary for Units that Use R407C
(and adaptability of tools that have been used with units that use R22) ...... 10
3Piping Materials .......................................................................... 11
4Storage of Piping Materials.......................................................... 12
[1] Storage Location .................................................................... 12
[2] Pipe sealing before storage.................................................... 12
5Machining Pipes .......................................................................... 13
6Brazing ........................................................................................ 14
7Testing Air Tightness.................................................................... 15
8Vacuum Drying (Evacuating) ...................................................... 16
9Charging the Circuit with Refrigerant .......................................... 17
0What to Do When Refrigerant Leaks .......................................... 19
AReplacing the Drier ...................................................................... 19
11. Restrictions
1System Restrictions and System Configuration .......................... 20
[1] Switch Setting ........................................................................ 20
2Restrictions on Transmission Lines.............................................. 22
[1] Electrical Wiring ...................................................................... 22
3Restrictions on Refrigerant Pipe Length...................................... 38
[1] Refrigerant Piping .................................................................. 38
22. Components of the Unit
1Internal Structure ........................................................................ 39
2Control Box .................................................................................. 42
3Main Board .................................................................................. 44
33. Electrical Wiring Diagrams
1Outdoor Unit ................................................................................ 49
2Indoor Unit.................................................................................... 50
44. Refrigerant Circuit
1Refrigerant Circuit Diagram ........................................................ 52
2List of Major Component Functions ............................................ 53

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55. Control
1Dip Switch Functions and Factory Settings ................................ 56
[1] Outdoor Unit .......................................................................... 56
[2] Indoor Unit .............................................................................. 57
2Controlling the Outdoor Unit ........................................................ 58
[1] Initial Control .......................................................................... 58
[2] Control at startup .................................................................... 58
[3] Bypass control ........................................................................ 58
[4] Frequency Control .................................................................. 59
[5] Oil-Return Control .................................................................. 60
[6] Outdoor Unit Fan .................................................................... 60
[7] Subcool Coil Control (Linear Expansion Valve (LEV1)).......... 60
[8] Circulating composition sensor (CS circuit)............................ 60
[9] Emergency Operation Mode .................................................. 61
[10] Capacity Control Between Outdoor Units (For P500 Type Only) .. 61
[11] Control-Block Diagram.......................................................... 62
[12] Operation Modes .................................................................. 62
3Controlling the Indoor Unit .......................................................... 63
[1] Thermostat Functions ............................................................ 63
[2] Actuator Control...................................................................... 64
[3] Temperature Setting Range .................................................... 64
[4] Emergency Operation Mode .................................................. 64
[5] Three-minute restart-suspension mode.................................. 65
[6] Anti-Freeze Control ................................................................ 65
[7] Operation during Electrical Power Failure .............................. 65
4Operation Flow Chart .................................................................. 66
[1] Mode Selection Flow Chart .................................................... 66
[2] Operation in each Mode ........................................................ 68
66. Refrigerant Amount Adjustment
1Operating Characteristics and Refrigerant Amount .................... 69
[1] Operating Characteristics/Refrigerant Amount ...................... 69
2Checking and Adjusting Refrigerant Amount .............................. 69
[1] Symptoms .............................................................................. 69
[2] Refrigerant Volume ................................................................ 69
[3] Amount of Refrigerant to Be Added ...................................... 70
3Refrigerant-Adjustment Operation Mode .................................... 71
[1] Procedures (only for air-cooled outdoor units) ...................... 71
77. Troubleshooting
1List of Check Code ...................................................................... 73
2Intermittent Fault Check Code (outdoor units only) .................... 74
3Self-Diagnosis and Problem-Solving Using Check Codes .......... 75
[1] Mechanical.............................................................................. 75
[2] Communication / System........................................................ 86
[3] System error .......................................................................... 93
[4] Troubleshooting using information on problems
with Remote Control, Input from External Source ................ 95
4Transmission Wave Pattern and Noise Check ............................ 99
[1] M-NET Transmission .............................................................. 99
[2] MA Remote Controller Transmission ...................................... 100
5Troubleshooting............................................................................ 102
[1] Principal Parts ........................................................................ 102

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88. LED Monitor Display
1How to Read the Service Monitor LED........................................ 115
[1] How to read the LED .............................................................. 115
[2] Outdoor Unit Control LED Monitor.......................................... 116
99. Test Run
1Before a Test Run ........................................................................ 124
2Test-Run Method.......................................................................... 124
3Not to Be Alarmed When the Following Symptoms Appear ........ 125
4Standard Operation (reference data) .......................................... 126
[1] Cooling Operation .................................................................. 126
[2] Operation under Other Conditions.......................................... 126
00. When Refrigerant Leaks
1Repairing Leaks: Preparation, making repairs, and recharging
the system with refrigerant .......................................................... 127
[1] Location of leaks: Extension piping or indoor unit .................. 127
[2] Location of leaks: Outdoor unit .............................................. 127
0011
. Circulating Composition Analysis
1Check the Composition of the Refrigerant .................................. 128

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Warning
Safety Precautions
Warning: Failure to follow all instructions may result in serious personal injury or death.
Caution: Failure to follow all instructions may result in personal injury or damage to the unit.
sAfter reading this handbook, hand it over to those who will be using the unit.
sThe user of the unit should keep this manual at hand and make it available to those who will be
performing repairs, to those who will be relocating the unit, and to new users.
Have the unit professionally installed.
• Improper installation by an unqualified person may result in
water leak, electric shock, or fire.
Only use specified cables for wiring. Securely connect
each cable, and make sure that the cables are not
straining the terminals.
• Cables not connected securely and properly may generate
heat and cause fire.
Do not make any changes or modifications to the unit. In
case of problems, consult the dealer.
• Inadequate repairs may result in water leak, electric shock,
or file.
Only use Refrigerant R407C.
• The use of any other refrigerant or the introduction of air
into the unit circuit may damage the unit.
Have all electrical work performed by a licensed
electrician according to the local regulations and the
instructions given in this manual.
Secure a circuit designated exclusively to the unit.
• Improper installation or a lack of circuit capacity at the
power source presents a risk of electric shock or fire.
Be sure to carefully follow each step in this handbook
when installing the unit.
• Improper installation may result in water leak, electric
shock, or fire.
Securely attach the terminal cover (panel) on the unit.
• If installed improperly, dust and/or water may enter the unit
and fire or electric shock may result.
When relocating the air conditioner, consult the dealer or
a specialist.
• Improper installation may result in water leak, electric
shock, or fire.
After completing service work, check for refrigerant gas
leaks.
• If leaked refrigerant gas is exposed to a heart source, such
as fan heater, stove, and electric grill, noxious gases may
form.
Only use specified parts, and have the unit professionally
installed.
• Improper installation may result in water leak, electric
shock, or fire.
When installing the unit in a small room, safeguard
against hypoxia, which is caused by the leaked refrigerant
exceeding the threshold level.
• Consult the dealer for necessary measures to take.
When a gas leak is detected, provide adequate ventilation
to the room.
• If leaked refrigerant gas is exposed to a heat source,
noxious gases may form.
Do not try to defeat the safety features of the devices, and
do not change the settings.
• Defeating the safety features such as the ones on pressure
switch and temperature switch or using parts other than
those specified by Mitsubishi Electric may result in fire or
explosion.
Place the unit on a stable, level surface that will withstand
the weight of the unit to prevent the unit from toppling
over.
Take necessary safety measures against typhoons and
earthquakes to prevent the unit from toppling over.
Do not touch the fins on the heat exchanger with bare
hands: they are sharp and dangerous.
sBefore installing the unit, be sure to read all the “Safety Precautions” very carefully.
sThey provide very important information regarding safety. Be sure to take these precautions to ensure safety.

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Caution
Precautions for Devices that Use R407C Refrigerant
Do not use existing refrigerant piping.
•The old refrigerant and refrigerator oil in the existing piping
contain a large amount of chlorine, which will deteriorate
the refrigerator oil in the new unit.
Use refrigerant pipes made of C1220 phosphorus
deoxidized copper categorized under H3000 (Copper and
Copper Alloy Seamless Pipes and Tubes), a standard set
by JIS.
•Keep inner and outer surfaces of the pipes clean and free
of contaminants, such as sulfur, oxides, dust/dirt, shaving
particles, oils, and moisture. Contaminants inside the
refrigerant piping will deteriorate the refrigerant oil.
Store the piping to be used during installation indoors,
and keep both ends of the piping sealed until immediately
before brazing. (Keep elbows and other joints wrapped in
plastic.)
•If dust, dirt, or water enters the refrigerant circuit,
deterioration of the oil or compressor problems may result.
Use a small amount of ester oil, ether oil, or alkylbenzene
to coat flares and flange connections.
•Refrigerator oil will deteriorate if it is mixed with a large
amount of mineral oil.
Be especially careful when managing tools.
•Exercise caution so that tools do not introduce dust, dirt,
and water into the refrigerant cycle.
Use liquid refrigerant to charge the circuit.
•Charging the unit with gas refrigerant will cause the
refrigerant in the cylinder to change its composition and will
lead to a drop in performance.
Only use R407C refrigerant.
•The use of other refrigerants containing chlorine (i.e. R22)
will deteriorate the refrigerant.
Do not use the following tools that have been used with
the existing refrigerators.
(Gauge manifold, charge hose, gas-leak detector, reverse-
flow-check valve, refrigerant charge base, vacuum gauge,
and refrigerant recovery equipment.)
•If refrigerant and / or refrigerant oil left on these tools are
mixed in with R407 or if water is mixed with R407C
refrigerant, the refrigerant will deteriorate.
•Since R407C does not contain chlorine, gas-leak detectors
for conventional refrigerators will not work.
Do not use a charging cylinder.
•The use of charging cylinder will change the composition of
the refrigerant and lead to power loss.
Use a vacuum pump with a reverse-flow-check valve.
•If other types of valves are used, the vacuum pump oil will
flow back into the refrigerant circuit and deteriorate the
refrigerator oil.

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Caution
Before Installing the Unit
Do not use the unit to preserve food, animals, plants, or
artifacts, or for other special purposes.
•The unit is not designed to provide adequate conditions to
preserve the quality of these items.
Use a closed circulating water circuit (which does not
release water in the air) as a heat source.
Do not install the unit in a place where there is a
possibility of flammable gas leak.
•Leaked gas accumulated around the unit may start a fire.
Do not use the unit in an unusual environment.
•Installing the unit in a place where a large amount of oil,
steam, or sulphurous gas is present may lead to a
remarkable drop in performance and/or damage to the unit.
Ground the unit.
•Do not connect the grounding on the unit to the grounding
terminals of gas pipes, water pipes, lightning rods, or
telephones. Improper grounding presents a risk of electric
shock.
Heat-Source Unit is only to be installed indoors (including
mechanical rooms). Make sure that the temperature
around the heat-source unit does not exceed 40˚CDB and
that it is out of direct sunlight.
•A sharp rise in the temperature inside the unit may damage
the unit.
When installing draining pipes, follow the instructions in
the manual and make sure that they properly drain water
as to prevent dew condensation.
•If not installed properly, water may leak and damage the
furnishings.
Make sure that the quality of circulating water meets the
standards set by Mitsubishi based on the Guidelines for
the Quality of Water for Refrigeration and Air Conditioning
established by the Japan Refrigeration and Air
Conditioning Industry Association.
•Using low-quality water may result in decreased
performance of the water-heat exchanger or corrosion.
Do not place the unit on or over things that should not get
wet.
•When humidity level exceeds 80% or when the drainage
system is clogged, indoor units may drip water. Installation
of a centralized drainage system for the heat-source unit
may also need to be considered to prevent water drips.
When installing the unit in hospitals, take necessary
measures against noise interference.
•High-frequency medical devices may interfere with the
normal operation of the air conditioning unit or vice versa.
•Water in an open circulating water circuit may become
contaminated when exposed to air and lead to a drop in
water-heat exchanger performance. It may also corrode the
exchanger.
Use breakers and fuses with proper current capacity. Do
not use large-capacity fuses, steel wire, or copper wire,
for they may damage the unit or cause fire.
For electrical wiring, use standard wires with proper
current capacity to prevent electric leak, overheating, and
fire.
Caution
Before Installing (Relocating) the Unit or Performing Electrical Work
Make sure the wires are not subject to tension.
•If the wires are too taut, they may generate heat and cause
fire.
Install a leak breaker at the power source to avoid the risk
of electric shock.
Do not spray water on air conditioners. Spraying the unit
presents a risk of electric shock.
Periodically check the platform on which the unit is placed
for damage to prevent the unit from toppling over.

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Caution
Before Installing (Relocating) the Unit or Performing Electrical Work
Turn on the unit at least 12 hours before the test run, and
keep the unit on throughout the season.
•If the unit is turned off during the season, problems may
occur.
Do not turn off the power immediately after stopping the
unit.
•Wait for at least five minutes; otherwise, the unit may leak
water or experience other problems.
Do not touch refrigerant piping with bare hands during
and immediately after operation.
•Depending on the state of the refrigerant in the system,
refrigerator parts such as piping and compressor may
become very hot or cold and may subject the person to
frost bites or burning.
Do not operate the unit without panels and safety guards
in their proper places.
•They are provided to keep the users from injury from
accidentally touching rotating, high-temperature, or high-
voltage parts.
Properly dispose of packing materials.
•Things such as nails and wood pieces may be included in
the package. Dispose of them properly to prevent injury.
•Plastic bags present a choking hazard to children. Tear up
the plastic bags before disposing of them to prevent
accidents.
Exercise caution when transporting products.
•Do not try to move equipments over 20kg (approx. 44 lbs.)
alone.
•Do not use the PP bands used on some packages for
transportation.
•Wear protective gloves to avoid injury caused by coming in
contact with the fins on the heat exchanger.
•When using suspension bolt to transport heat-source unit,
use four-point suspension. Three-point suspension does
not provide adequate stability and presents a risk of injury.
Caution
Before the Test Run
To prevent the risk of electric shock, do not operate
switches with wet hands.
Do not operate the unit without air filters.
•Dust particles in the air may clog the system.

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Please Read Before Servicing the Unit
11Check Before Servicing the Unit
[1] Find out the model type and refrigerant type of the unit to be serviced.
[2] Principal System Components
PUD-P250YMF-C
10HP(downward flow): PFD-P250VM-A(-H)
20HP(downward flow): PFD-P500VM-A(-H)
✻ '-H' in the indoor units indicates that the unit pipes come out of the top of the unit (50/60Hz, fit to order).
✻ PFD-type indoor units cannot be connected to outdoor units other than the ones specified above.
✻ PFD-type indoor units and other types of indoor units cannot coexist in the same refrigerant system.
} Outdoor Unit
} Indoor Unit
<10HP System>
<20HP System>
When using a PFD-P500VM-A as an indoor unit, connect 2 PUD-P250YMF-C outdoor units to each
indoor unit and operate with a built-in remote control for the indoor unit.
✻1: Bold line indicates refrigerant piping (gas/liquid). This system consists of 2 refrigerant circuits.
✻2: Indicates TB3-type transmission line that connects the indoor and outdoor units.
This system consists of 2 refrigerant circuits.
✻3: Indicates TB7-type transmission line that allows the unit to communicate with the controller.
When using a PFD-P250VM-A as an indoor unit, connect an outdoor unit PUD-P250YMF-C to
each indoor unit and operate with a built-in remote control for the indoor unit.
✻1: Bold line indicates refrigerant piping (gas/liquid). This system consists of one refrigerant circuit.
✻2: Indicates TB3-type transmission line that connects the indoor and outdoor units.
This system consists of 1 refrigerant circuit.
✻3: Indicates TB7-Type transmission line that allows the unit to communicate with the controller.
Outdoor Unit
G-50A
PUD-P250YMF-C
Indoor Unit
PFD-P250VM-A
TB7 TB3 ✻2✻3
✻1
12V DC
M-NET
PAC-SC50KUA
UP
POWERRATING
MODEL
WEIGHT
SERIALNo.
2.11kg
POWERSUPPLYUNIT
MITSUBISHIELECTRICCORPORATION
PAC-SC50KUA
Outdoor Unit
PUD-P250YMF-C
Indoor Unit
PFD-P500VM-A
TB7 TB3 ✻2
✻1
TB3
PUD-P250YMF-C
TB7
✻3
G-50A
12V DC
M-NET
PAC-SC50KUA
UP
POWERRATING
MODEL
WEIGHT
SERIALNo.
2.11kg
POWERSUPPLYUNIT
MITSUBISHIELECTRICCORPORATION
PAC-SC50KUA

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[3] Check the symptoms of the unit requiring service.
Refer to this service manual for problems related to Freezer Cycle.
[4] Be sure to read Read Before Servicing at the beginning of this manual.
[5] Prepare necessary tools.
Do not use the same tools for units that use different types of refrigerant (especially gauze manifold and
charge hose). Doing so may cause problems. Use a vacuum pump with a reverse-flow check valve or use a
reverse flow check adapter.
[6] If the refrigerant circuit is opened (to repair gas leak etc.), the drier needs to be
replaced.
Only use the drier designed specifically for the unit. The use of other driers may result in malfunctions. Refer to
section 11 of this manual for information regarding how to change the drier.
✻Replace the drier after completing refrigerant circuit repairs.
(If left exposed to air, the drier will absorb moisture. Replace the drier as quickly as possible after removing
the old one.)
[7] Preparing the connecting pipes: When relocating or replacing the unit, find out what
types of refrigerant is used for the unit.
Use refrigerant pipes made of C1220 phosphorus deoxidized copper categorized under H3000 (Copper and
Copper Alloy Seamless Pipes and Tubes), a standard set by JIS. Keep inner and outer surfaces of the pipes
clean and free of contaminants, such as sulfur, oxides, dust/dirt, shaving particles, oils, and moisture.
Contaminants inside the refrigerant piping will deteriorate the refrigerant oil.
[8] If there is a gas leak or if the remaining refrigerant is exposed to an open flame, a
noxious gas hydrofluoric acid may form. Provide adequate ventilation.
.Caution
1. As soon as the old parts are removed, put in the new ones. Keep moisture from entering pipes while cooling.
2. Using refrigerant containing chlorine (such as R22) will result in the deterioration of oil in the new unit.

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NotesUseTools
Identification of dedicated use with
R407C: Record refrigerant name
and put a brown belt on the upper
part of the cylinder.
Use a small amount of ester oil,
ether oil, or alkybenzene.
The ones with sight glass are useful.
Can also be used with R134a.
Gauge Manifold
Refrigerant Collector
Gas Leak Detector
Charge Hose
Refrigerant Cylinder
Application Oil
Evacuating, refrigerant
charging and operation check
Gas leak detection
Refrigerant collection
Refrigerant charging
Applied to flares and flanges
Attach a reverse-flow-check adaptor
Refrigerant Cylinder Intake Refrigerant charging Replace the packing with the one
for R407C
Modifications to Be MadeUseTools
Vacuum Pump Vacuum drying
Vacuum Pump with a Check valve
Vacuum Gauze
Refrigerant Charging Meter
Welder and Nitrogen Cylinder
Pipe Cutter
Torque Wrench
Bender
Flare Tool Flaring pipes
Checking vacuum degree
Refrigerant charging
Welding pipes
Cutting pipes
Tightening flare nuts
Bending pipes
NotesUseTools
Must not be used with R407C-type
units
NotesUse (with R22)Tools
Charging Cylinder Refrigerant Charging
22Necessary Tools and Materials
Prepare the following tools and materials. Some of the tools should be marked for use only with units that use
R407C refrigerant.
[1] List of Tools and Materials Necessary for Units that Use R407C (and adaptability of
tools that have been used with units that use R22)
(1) To be used with R407C Only (not to be used if used with R22)
(2) Tools that may be used for R407C if necessary modifications are made
(3) Tools that are used with R22 that can also be used with R407C
(4) Tools that must not be used for R407C
Tools for R407C must be handled with special care.

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Do not use the piping that have been used for R22.
<Reason>
A large amount of chlorine residues from conventional refrigerator oil and refrigerant found inside the existing
piping deposit sludge in the new piping system.
<Caution>
1. When replacing the air conditioner, also replace the piping.
2. Use refrigerant pipes made of C1220 phosphorus deoxidized copper categorized under H3000 (Copper and
Copper Alloy Seamless Pipes and Tubes), a standard set by JIS. Keep inner and outer surfaces of the pipes
clean and free of contaminants, such as sulfur, oxides, dust/dirt, shaving particles, oils, and moisture.
3. Contaminants inside the refrigerant piping may deteriorate the refrigerant oil.
33Piping Materials
NOOK
New Piping Existing Piping
Do not use the existing piping!

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44Storage of Piping Materials
[1] Storage Location
NONO
OKOK
NONO
OKOK
Store the pipes to be used indoors (i.e. warehouse).
Storing them outdoors may cause dirt, waste, or water to infiltrate.
[2] Pipe sealing before storage
Both ends of the pipes should be sealed until immediately before brazing.
Wrap elbows and T’s in plastic for storage.
✻The new refrigerator oil is ten times more hygroscopic than conventional refrigerator oils (such as Suniso).
Water infiltration in the refrigerant circuit will deteriorate the oil or cause a compressor failure. Exercise more
caution when handling piping materials for R407C air conditioners than you would when handling piping
materials for conventional units.

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55Machining Pipes
Use a small amount of ester oil, ether oil, or alkylbenzene as refrigerator oil to coat flares and flange connections.
<Caution>
Use only the smallest possible amount of oil necessary.
Do not use oils other than ester oil, ether oil, or alkylbenzene.

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<Items to be strictly observed>
1. Do not conduct piping work outdoors on a rainy day.
2. Apply non-oxide brazing.
3. Use brazing material (BCuP-3), which requires no flux when brazing copper pipe or brazing a copper pipe and
copper coupling.
4. If the installed refrigerant pipes are not immediately connected to the unit, braze and seal both ends of the
pipes.
<Rationale>
1. The new refrigerant oil is ten times more hygroscopic than conventional oils. Special care must be taken to
keep moisture out of the system.
2. Flux generally contains chlorine. A residual flux in the refrigerant circuit may deposit sludgy materials in the
pipes.
<Caution>
Because the residue found in commercially available antioxidants may have adverse effects on the unit, use
nitrogen when performing non-oxide brazing.
66Brazing
Although there are no changes from the conventional method, special care must be taken to keep contaminants
(i.e. oxide scale, water, dirt etc.) from entering refrigerant circuit.
Example: Inside a brazed section
Brazed with materials other than non-oxide
brazing material Brazed with non-oxide brazing material

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NO NO
77Testing Air Tightness
There are no changes from the conventional method. Note that a refrigerant leak detector for R22 will not work
for R407C.
<Items to be strictly observed>
1. Pressurize the equipment with nitrogen up to the design pressure, and then measure the equipment’s air-tight-
ness, taking temperature variations into account.
2. When investigating locations of leaks using a refrigerant, be sure to use R407C.
3. Make sure that R407C is in a liquid state when charging the circuit.
<Rationale>
1. Use of oxygen to pressurize the equipment may cause an explosion.
2. If gas refrigerant is used, the composition of the remaining refrigerant in the cylinder will change and become
unusable.
<Caution>
A leak detector for R407C is commercially available, and it should be acquired.
Halide Torch R22 Leak Detector

- 16 -
[1] Vacuum pump with a check valve (See photo 1)
A vacuum pump with a check valve is required to prevent the vacuum pump oil from flowing back into the
refrigerant circuit when the power supply is cut off unexpectedly due to power outage.
A check valve may be added to a vacuum pump that is not equipped with one.
[2] Standard degree of vacuum for the vacuum pump
Use a pump that does not exceed 65Pa after 5 minutes of operation. Be sure to use a vacuum pump that has
been properly maintained and oiled with specified oil. If the vacuum pump is not properly maintained, desired
degree of vacuum may not be achieved.
[3] Necessary Accuracy of the Vacuum Gauge
Use a vacuum gauge that can measure 650Pa and in the increments/decrements of 130Pa. Do not use gauge
manifolds that cannot measure a vacuum of 650Pa. (Recommended vacuum gauze shown in Photograph 2
above)
[4] Vacuuming time
Evacuate the equipment for one hour after reaching 650Pa. (Moisture in the air will be removed by a thorough
evacuation.)
After evacuating, leave the equipment for one hour and make sure that degree of vacuum does not rise higher
than 130Pa. Refer to section 6 “Special Vacuuming Method”if it exceeds 130Pa.
[5] How to Stop the Vacuum Pump
In order to prevent a backflow of the vacuum pump oil, open the relief valve on the vacuum pump or loosen the
charge hose to draw in air before stopping the operation. The same operating procedure should be followed
when using a vacuum pump with a check valve.
[6] Special Vacuuming Method
Water infiltration or leakage is suspected when the degree of vacuum does not go below 650Pa after running
the vacuum pump for more than 3 hours. Check for leakage and water infiltration.
If water infiltration is the suspected cause, break vacuum with nitrogen. Then, pressurize nitrogen gas to
0.05MPa and try evacuating again. Repeat the procedure until the degree of vacuum goes below 650Pa or
until the pressure stops rising.
Be sure to use nitrogen to break vacuum. (The use of oxygen may cause an explosion)
Photograph 1 Photograph 2
Photograph 1 Recommended Vacuum Gauge : ROBINAIR 14010 Thermistor Vacuum Gauge
88Vacuum Drying (Evacuating)

- 17 -
99Charging the Circuit with Refrigerant
R407C must be in a liquid state when charging the circuit because it is a non-azeotropic refrigerant.
<Rationale>
1. R407C is a mixture of three refrigerants, each with a different evaporation temperature. If the equipment is
charged with R407C gas, only the refrigerant that evaporates most easily is charged, while the rest of the
refrigerants remain in the cylinder.
<Caution>
Do not use cylinders with a siphon upside-down.
When using a cylinder with a siphon, R407C is charged in a liquid state without the cylinder being turned upside-
down. Check the label on the cylinder for information about the type of cylinder before the operation. (Cylinders
with siphons manufactured by Asahi Glass are shown on Page 18)
cylinder with a siphon
Cylinder color R407C-Brown
Cylinder
Cylinder
cylinder without a siphon
Use liquid refrigerant
Valve Valve
Liquid Liquid

- 18 -
Enlargement
Valve
Liquid
R407C Cylinder with siphon: Manufactured by Asahi Glass
.Caution
The cylinders shown below are equipped with siphons.
When using this type of cylinders, place the cylinder
with the siphon facing up.

- 19 -
Drier
Direction of the flow Top to bottom
ø 9.52
Flare connection
ø 12.7
Flare connection
,
AAReplacing the Drier
==What to Do When Refrigerant Leaks
As with conventional air-conditioning units, refrigerant can be added to what remains in the circuit, for the unit is
equipped with a CS circuit (Circulating-Refrigerant-Composition-Detector) Refer to section X of this handbook for
more information.
✻When using water-cooled heat-source unit, please note that CS circuit is only found on the inverter side, but not
on the constant-rate side.
1. Replace the drier when the refrigerant circuit is opened. Only use the drier specified for this unit. The use of any
other drier will cause malfunctions.
2. Install the drier as shown in the photograph below. Do not attach driers to a pipe;
doing so may cause problems.
3. Do not leave the refrigerant circuit open for longer than one hour after removing the old drier. The replacement of
the drier should be performed last when performing multiple jobs.