The Signature Series is NOT designed for amateur installation. Installation SHOULD be performed by an authorized technician.
Please read this manual carefully before installation and keep it for future reference.
Owner & Installation
Manual
Signature Series
MPG*S*M414A Residential Package
The Signature Series is NOT designed for amateur installation. Installation SHOULD be performed by an authorized technician.
Please read this manual carefully before installation and keep it for future reference.
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
WARNING
If this unit is to be installed in a mobile or manufactured
home application, the duct system must be sized to
achieve static pressures within the manufacturer’s
guidelines. All other installation guidelines must also
be followed. Failure to do so may result in equipment
damage, personal injury, and improper performance of
the unit.
INSTALLATION AND MAINTENANCE
INSTRUCTIONS
MPG*S*M414A SERIES UNITS
RESIDENTIAL PACKAGED UNITS
Gas/Electric
507295-02C
4/2019
Table of Contents
Installation ...................................................................2
Venting.........................................................................4
Duct System ................................................................5
Filters...........................................................................5
Condensate Drain........................................................5
Gas Piping...................................................................6
Electrical Wiring ..........................................................7
Heating Start-Up .........................................................8
Operation...................................................................10
Maintenance..............................................................11
WARNING
Do not store combustible materials, including gasoline
vent pipe, or warm air ducts. Such actions could cause
property damage, personal injury, or death.
WARNING
Improper installation, adjustment, alteration, service, or
maintenance can cause injury or property damage. Refer
to this manual. For assistance or additional information,
consult a licensed professional (or equivalent), HVAC
installer, service agency, or the gas supplier.
Manufactured By
MRCOOL LLC
Hickory, KY 42051
*F507295-C*
(P) 507295-02C
CAUTION
The installation of the unit, wiring, warm air ducts, venting, etc. must conform to the requirements of the National Fire
Protection Association; the National Fuel Gas Code, ANSI Z223.1 (latest edition) and the National Electrical Code, ANSI/
NFPA No. 70 (latest edition) in the United States; the Canadian Installation Codes CAN/CGA-B149.1 & .2 (latest edition)
and the Canadian Electrical Code Part 1, CSA 22.1 (latest edition) in Canada; and any state or provincial laws, local
ordinances, or local gas utility requirements. Local authorities having jurisdiction should be consulted before installation
is made. Such applicable regulations or requirements take precedence over the general instructions in this manual.
Save these instructions for future reference
507295-02C Page 1 of 13mrcool.com
Installation
These instructions must be saved for future reference.
These units are single package air conditioners with gas
heat designed for outdoor installation on a rooftop or a
slab.
Inspection
As soon as the unit is received, it should be inspected
for possible damage during transit. If damage is evident,
the extent of the damage should be noted on the carrier’s
freight bill. A separate request for inspection by the carrier’s
agent should be made in writing.
The units are completely assembled. All piping, refrigerant
charge, and electrical wiring are factory installed and
tested. The units require only electric power, gas piping,
condensate drain, and duct connections, plus installation
of the vent cover at the point of installation.
If components are to be added to a unit to meet local codes,
they are to be installed at the dealer’s and/or customer’s
expense.
The size of unit for the proposed installation should be
based on heat loss/heat gain calculation made according
to the methods of Air Conditioning Contractors of America
(ACCA).
WARNING
In the State of Massachusetts:
This product must be installed by a licensed Plumber
maximum length shall not exceed 36”. When lever-type
gas shutoffs are used, they shall be T-handle type.
These installation instructions are intended as a
contractor.
Inc.:
• For use as a forced air furnace with cooling unit.
• For outdoor installation only.
• For installation on combustible material.
• For use with natural gas or propane gas. (Conversion
kit required for propane gas application.)
These units are not suitable for use with conventional
venting systems.
Location
Use the following guidelines to select a suitable location
for these units.
1. Unit is designed for outdoor installation only. Unit must
be installed so all electrical components are protected
from water.
2. Condenser coils must have an unlimited supply of air.
3. For ground level installation, use a level prefabricated
pad or use a level concrete slab. Do not tie the slab to
the building foundation.
4. Maintain level within a tolerance of 1/4” maximum
across the entire length or width of the unit.
CAUTION
5. Do not locate the unit where the combustion air supply
will be exposed to any of the following substances:
• Permanent wave solutions
• Chlorinated waxes and cleaners
• Chlorine-based swimming pool chemicals
• Water softening chemicals
• Deicing salts or chemicals
• Carbon tetrachloride
• Halogen-type refrigerants
• Cleaning solvents (such as perchloroethylene)
• Printing inks, paint removers, varnishes, etc.
• Cements and glues
• Antistatic fabric softeners for clothes dryers
• Masonry acid washing materials
• Chlorinated laundry products
• Hydrochloric acid
Page 2 of 13 507295-02Cmrcool.com
Clearances
All units require certain clearances for proper operation
and service. Refer to Table 1 for the minimum clearances
to combustibles, servicing, and proper unit operation. In
made from wood or class A, B, or C roof covering material.
Units must be installed outdoors.
Do not permit overhanging structures or shrubs to
obstruct condenser air discharge outlet, combustion
air inlet, or vent outlet.
Clearance to
Combustibles
Front of unit 0 in. 24 in.
Back of unit 0 in. 0 in.
Left side 0 in. 24 in.
Right side (from
vent hood)
Base of unit 0 in. 0 in.
Top of unit 0 in. 48 in.
temperatures. For any future service, installer must provide
access to screws of top and rear panels.
12 in. 24 in.
Clearance for
Service Access
Table 1. Minimum Clearances
Roof Curb Installation
If a roof curb is used, follow the manufacturer’s Installation
Instructions and be sure that all required clearances are
observed (see Clearances section).
Rigging Unit
Exercise care when moving the unit. Do not remove any
packaging until the unit is near the place of installation.
An optional lifting lug kit may be purchased separately for
use in rigging the unit for lifting. Spreaders whose length
exceeds the unit depth dimension by 6 inches MUST be
used across the top of the unit.
Units may also be moved or lifted with a forklift while still in
the factory supplied packaging. The lengths of the forks
of the forklift must be a minimum of 42 inches.
Figure 1.
CAUTION
Before lifting a unit, make sure that the weight is
distributed equally on the cables so that it will lift evenly.
Unpacking
Carefully remove outer packaging material and discard.
Locate the four (4) shipping brackets that attached the
unit to the wood pallet and remove. Locate the supply duct
corner and seal the shipping openings in the base from
the underside with silicone or other approved sealant to
prevent air leakage during unit operation.
Service Access
Access to all serviceable components is provided by four
removable panels: upper access panel (for blower, ID coil,
panel, and compressor access.
CAUTION
As with any Mechanical equipment, personal injury can
result from contact with sharp sheet metal edges. Be
careful when you handle this equipment.
507295-02C Page 3 of 13mrcool.com
WARNING
This unit is charged with HFC-410A refrigerant.
Operating pressures for units charged with HFC-410A
are higher than pressures in units charged with HCFC-
22. All service equipment MUST be rated for use with
HFC-410A refrigerant.
Venting
The vent outlet must be installed in a location as to prevent
building degradation and must be consistent with the
National Fuel Gas Code, Z223.1 or CAN/CGA-B149.1 &
.2.
The products of combustion are discharged through
a screened opening on the gas heat side panel. The
horizontal vent system shall terminate at least 4 feet below,
4 feet horizontally from, or 1 foot above any door, window,
or gravity air inlet into the building. The vent system shall
terminate at least 3 feet above any forced air inlet located
within 10 feet.
The unit shall be installed in a manner such that snow
Minimum horizontal clearance of 4 feet from electric meters,
gas meters, regulator, and relief equipment is required.
In addition to the above requirements, consideration must
be given to prevent unwanted ice buildup from the vent
condensate. The vent should not be located on the side of
a building where the prevailing winter winds could trap the
moisture, causing it to freeze on the walls or on overhangs
(under eaves). The vent should not be located over a
sidewalk, patio, or other walkway where the condensate
could cause the surface to become slippery.
The products of combustion must not be allowed to
be recirculated.
Vent Hood Installation
The unit is shipped with the vent hood inside the control
compartment. Locate the vent hood and attach to side of
utility panel with screws provided in the instruction bag
(see Figure 2).
NOTE:
If an existing gas furnace is being removed from a
common venting system when this packaged unit is
installed, then read and follow the instructions in the
“Removal of Unit from Common Venting System” section
that follows. Otherwise, you may skip this section.
Removal of Unit from Common Venting System
When an existing furnace is removed from a common
venting system serving other appliances, the venting
system is likely to be too large to properly vent the
remaining attached appliances. The following test
should be conducted with each appliance while the other
appliances connected to the common venting system are
not in operation.
1. Seal any unused openings in the common venting
system.
2. Visually inspect the venting system for proper size and
horizontal pitch and determine there is no blockage
which could cause an unsafe condition.
3. Insofar as is practical, close all building doors and
windows between the space in which the appliances
remaining connected to the common venting system
are located and other spaces in the building. Turn on
clothes dryers and any appliance not connected to the
common venting system. Turn on exhaust fans, such
as range hoods and bathroom exhausts, so they will
operate at maximum speed. Do not operate a summer
4. Following the lighting instructions, place the unit being
inspected in operation. Adjust the thermostat so the
appliance will operate continuously.
5. Test for spillage at the draft control relief opening after
6. Follow the preceding steps for each appliance
7. After it has been determined that each appliance
8. If improper venting is observed during any of the
Figure 2. Installing the Vent Cover
Page 4 of 13 507295-02Cmrcool.com
a match or candle.
connected to the common venting system.
remaining connected to the common venting system
properly vents when tested as outlined above, return
and any other fuel burning appliance to their previous
condition of use.
above tests, the common venting system must be
corrected. See National Fuel Gas Code, ANSI Z223.1
(latest edition) or CAN/CGA B149.1 & .2 Canadian
Installation Codes to correct improper operation of
common venting system.
Duct System
The duct system should be designed and sized according
to the methods in Manual Q of the Air Conditioning
Contractors of America (ACCA).
A closed return air duct system shall be used. This shall
not preclude use of economizers or outdoor fresh air
intake. It is recommended that supply and return air duct
The supply and return air duct systems should be designed
for the CFM and static requirements of the job. They
should not be sized by matching the dimensions of the
duct connections on the unit.
connections). Before attaching side ducts, bend perforated
duct tabs out to assist with duct alignment and attachment.
Duct attachment screws are intended to go into the duct
panel. Duct to unit connections must be sealed and
weather proofed.
Filters
NOTE:
the unit in applications where access to the rear panel
is limited.
Unit Model Filter 1 Filter 2
24, 30, 36 14 X 20 20 X 20
42, 48, 60 20 X 20 20 X 20
kit is required, and the following conversion is required.
1. Using a knife, cut following the marked cut lines on
the unit base insulation to access bottom metal covers
underneath the insulation.
2. Remove the screws securing the bottom covers, and
discard the bottom covers (supply and return).
3. Remove screws located between the supply and return
air openings that attach the blower deck to the base,
and discard these screws. These screws can interfere
with bottom duct connections or roof curb seals.
4.
conversion kit over the side duct openings (use
dimples on back panel to locate cover attachments).
5.
Table 2. Unit Air Filter Sizes - inches
Condensate Drain
This package unit is equipped with a 3/4” FPT coupling
for condensate line connection. Plumbing must conform
to local codes. Use a sealing compound on male pipe
threads.
Do not operate unit without a drain trap. The condensate
drain is on the negative pressure side of the blower;
therefore, air being pulled through the condensate line will
prevent positive drainage without a proper trap.
The condensate drain line must be properly trapped,
routed to a suitable drain and primed prior to unit
commissioning.
NOTE: Install drain lines and trap so they do not block
service access to the unit.
See Figure 3 for proper drain arrangement. The drain line
must pitch to an open drain or pump to prevent clogging
of the line. Seal around the drain connection with suitable
material to prevent air leakage into the return air system.
To prime trap, pour several quarts of water into drain,
507295-02C Page 5 of 13mrcool.com
CAUTION
Drain lines should be hand-tightened only. Do not use
WARNING
MINIMUM PITCH
1 IN (25) PER 10” (3048
MM) OF LINE
OPEN
VENT
Trap must be deep enough to offset maximum static difference
(generally, 3 inches (76 mm) minimum). In addition, the drain line
must be supported if longer than 10 feet.
Trap must be primed at start-up.
UNIT
MOUNTING
FRAME
Figure 3. Typical Condensate Drain Connection
causing injury or death may occur.
•
must be disconnected from the gas supply piping
system during any pressure testing of that system at
test pressures in excess of 1/2 PSIG (3.48kPa).
• A 1/8” N.P.T. plugged tapping, accessible for test
gauge connections, must be installed immediately
upstream of the gas supply connection to the furnace.
Gas Connection
The gas supply line is routed through the gas entry
location on the side of the unit (see Figure 4). A grommet is
provided in the instruction bag and should be used to seal
gas supply line to gas entry of control compartment.
Gas Piping
Proper sizing of a gas piping depends on the cubic feet per
length of run. National Fuel Gas Code Z223.1 latest edition
should be followed in all cases unless superseded by local
codes or gas company requirements. In Canada, refer to
CAN/CGA B.149.1 & .2 (latest edition).
The heating value of the gas may differ with locality. The
value should be checked with the local gas utility. For
temperature rise of unit, see unit rating plate.
Gas Piping Recommendations
• A drip leg and a ground joint union must be installed in
the gas piping. A ground joint union is recommended
by the manifold/valve.
• When required by local codes, a manual shutoff valve
may have to be installed outside of the unit.
• Use pipe thread sealing compound resistant to
propane gas sparingly on male threads.
• The gas supply should be a separate line and installed
in accordance with all safety codes listed on Page
1. After the gas connections have been completed,
open the main shutoff valve admitting normal gas
pressure to the mains. Check all joints for leaks
with soapy solution or other material suitable for the
purpose.
Figure 4.
WARNING
The furnace must be isolated from the gas supply piping
during any pressure testing of gas supply piping system
at test pressures equal to or less than 1/2 psig or 14”
w.c. If the piping system is to be tested at pressures in
excess of 1/2 psig, the furnace and its individual shutoff
valve must be disconnected from the gas supply piping
system.
NOTE: LPG/Propane Units, Tanks, and Piping
Units are shipped equipped for use with natural gas,
approved licensed technician. If conversion is required,
use the approved conversion kit.
Page 6 of 13 507295-02Cmrcool.com
When converting a low NOx unit (designated by an L in
some model numbers) to propane, the NOx inserts must
be removed.
All LPG/propane gas equipment must conform to the safety
standards of the National Fire Protection Association.
For satisfactory operation, LPG/propane gas pressure
must be a minimum of 11” w.c. at the unit under full load.
Complete information regarding tank sizing for
vaporization, recommended regulator settings, and pipe
sizing is available from most regulator manufacturers and
LPG/propane gas suppliers.
Check all connections for leaks when piping is completed,
using a soapy, non-chlorine based solution. Some soaps
used for leak detection are corrosive to certain metals.
Carefully rinse piping thoroughly after completing
leak detection.
WARNING
of the type shown on the wiring diagram. Electrical wiring
must be sized to carry minimum circuit ampacity marked
on the unit. Use copper conductors only. Each unit must
be wired with a separate branch circuit and be properly
fused.
FIELD-SUPPLIED FUSED
CONTACTOR
If 208 Volt is supplied, transformer connection must be
changed
GROUND
LUG
OR CIRCUIT BREAKER
DISCONNECT
SINGLE PHASE
POWER SUPPLY
Figure 5. 208/230 Line Voltage Wiring
Danger of explosion. Can cause injury or product or
or other sources of ignition to check for leaks.
CAUTION
the authority that has jurisdiction, black iron pipe shall
be installed at the gas valve and must extend outside
between the black iron pipe and the gas supply line.
Electrical Wiring
See Figure 4 and Figure 5
All wiring should be done in accordance with the National
Electrical Code, ANSI/NFPA No. 70 (latest edition);
Canadian Electrical Code Part 1, CSA C22.1 (latest
edition); or local codes where they prevail. Use wiring with
a temperature limitation of 75°C minimum. Run the 208 or
230 volt, 60 hertz electric power supply through a fused
disconnect switch to the control box of the unit and connect
as shown in the wiring diagram located on the inside of the
control access panel.
CAUTION
When connecting electrical power and control wiring
to the unit, waterproof type connectors must be used
so that water or moisture cannot be drawn into the unit
during normal operation.
Thermostat
The room thermostat should be located on an inside
wall where it will not be subject to drafts, sun exposure,
manufacturer’s instructions enclosed with thermostat for
general installation procedure. Color-coded insulated wires
(#18 AWG) should be used to connect the thermostat to
the unit.
Four wires are required for cooling. The heat anticipator
setting is 0.75 amp.
Compressor
Units are shipped with compressor mountings factoryadjusted and ready for operation.
CAUTION
Do not loosen compressor mounting bolts.
Power supply to the unit must be N.E.C. Class 1, and must
comply with all applicable codes. A fused disconnect switch
separate from all other circuits. If any of the wire supplied
with the unit must be replaced, replacement wire must be
507295-02C Page 7 of 13mrcool.com
Red
Blue
Yellow
White
Green
4. Turn on electrical power to the unit.
5. Set the room thermostat to the desired temperature.
(If the thermostat “set” temperature is above room
temperature after the pre-purge time expires, main
burners will light.)
To Shut Down Main Burners
1. Turn off electrical power to unit.
2. Slide the gas valve switch to the “OFF” position (see
Figure 7).
Regulator
Adjustment
Figure 7. Gas Valve
75
Figure 6. Typical Wiring Connections
Heating Start-Up
For Your Safety, Read Before Lighting
CAUTION
Furnace is equipped with a direct ignition control. Do
not attempt to manually light the burners.
Pre-Start Checklist
Complete the following checks before starting the unit:
1. Check the type of gas being supplied. Be sure it is the
same as listed on the unit nameplate.
2. Make sure that the vent cover has been properly
installed.
To Light Main Burners
1. Turn off electrical power to unit.
2. Turn the thermostat to lowest setting.
3. Slide the gas valve switch to the “ON” position (see
Figure 7).
Post-Start Checklist
After the entire control circuit has been energized and the
heating section is operating, make the following checks:
1. Check for gas leaks, using soapy solution, in the unit
piping as well as the supply piping.
2. Check for correct manifold gas pressures (see Manifold
Gas Pressure Adjustment Regulator sections).
3. Check the supply gas pressure. It must be within the
limits shown on the rating plate. Supply pressure
should be checked with all gas appliances in the
pressure exceed 13” w.c., nor the operation pressure
drop below 5” w.c. for natural gas units or 11” w.c. for
propane gas. If gas pressure is outside these limits,
contact the gas supplier for corrective action.
4.
rating plate.
Manifold Gas Pressure Adjustment Regulator – Natural
Gas
For purpose of input adjustment, the minimum permissible
gas supply pressure is 5” w.c. for natural gas.
Gas input must never exceed the input capacity shown on
the rating plate. The furnace is equipped for natural gas
rated inputs with manifold pressure of 3.5” w.c.
The manifold pressure can be measured by shutting off
the gas, removing the pipe plug in the downstream side
of the gas valve, and connecting a water manometer
or gauge.
manifold pressure vary more than 0.3” w.c. from the
Page 8 of 13 507295-02Cmrcool.com
To adjust the regulator, turn
the adjusting screw on the regulator clockwise to increase
pressure and input or counterclockwise to decrease
pressure and input. See Figure 7 to assist in locating the
regulator on the gas valve.
Check the furnace rate by observing the gas meter, making
sure all other gas appliances are turned off. The test hand
on the meter should be timed for at least one revolution,
noting the number of seconds per revolution. The heating
value of the gas can be obtained from the local utility.
Cubic Feet per
BTU/HR
Input
=
Revolution
# Seconds per
Revolution
x 3600 x
Heating
Value
For example, by actual measurement, it takes 38 seconds
for the hand on the 1-cubic foot dial to make a revolution
with a 100,000 BTU/HR furnace running. The result is
99,750 BTU/HR, which is close to the 100,000 BTU/HR
rating of the furnace.
Manifold Gas Pressure Adjustment Regulator – LPG/
Propane Gas
LPG/propane units require a LPG regulator on both the
gas valve and on the LPG/propane tank.
IMPORTANT: For purpose of input adjustment, the
minimum permissible gas supply pressure (inlet side of
gas valve) is 11” w.c. for LPG/propane.
If at any time ignition is slow and burner does not seem to
be operating correctly, check manifold pressure (outlet side
of the gas valve). It should be 10” to 10.5” w.c. pressure
for LPG/propane.
The furnace is designed to obtain rated input at 10”
w.c. manifold pressure for propane.
High Altitude
The input rate shown on the rating plate is for elevations
up to 2000 feet. For elevations from 2001 to 4500 feet,
the input rate is reduced by 5%. For elevations above
4500 feet, refer to the National Fuel Gas Code Z223.1
(latest edition) or the Canadian Installation Codes CAN/
CGA-B149.1 & B149.2 for further details.
To check this pressure:
1. Slide the gas valve switch to the “OFF” position (see
Figure 7).
2. Remove plug on valve marked “OUTLET PRESSURE.”
3. Install a water manometer.
4. Slide the gas valve switch to the “ON” position and
initiate a call for heat.
If manifold pressure must be
adjusted, remove cap from pressure regulator and
turn adjustment screw clockwise to increase pressure
or counterclockwise to reduce pressure.
5. After checking pressure, turn gas off, remove
cap.
6. Put furnace in operation and check plug for leaks
using soapy solution.
1. Close the main manual gas shutoff valve and turn
off all power to unit.
2. Remove the burner access panel.
3. Disconnect the union in the gas supply line upstream
of the gas valve and downstream of the manual shutoff
valve.
4. Label wires going to the gas valve, then disconnect
the wires.
5.
a. Remove screws that fasten the manifold to the
burner box assembly and remove the manifold.
b.
c. To reassemble: Reverse above steps, making
on the back end of the burners, and that burners
are level and centered on each burner opening in
the vest panel.
6. To remove or service burners:
a. Label and disconnect the wires to the rollout switch
at the ignition control.
b. Remove the screws that secure the burner box
assembly to the vest panel and remove the
assembly from the unit.
c. Remove the screws that fasten the burner rack
and bottom shield assembly to the burner box.
Burners are now accessible for removal.
d. To Reassemble: Reverse above steps.
7. After reassembly of all parts is complete and all wires
are reconnected, open the main manual gas shutoff
valve; check for and correct any gas leaks. Turn
electrical power on, initiate a call for heat, and check
for proper burner operation.
8. Install burner access panel.
Heat Anticipator
The heat anticipator setting is 0.75 amp. It is important
that the anticipator setpoint be correct. Too high of a setting
will result in longer heat cycles and a greater temperature
swing in the conditioned space. Reducing the value below
the correct setpoint will give shorter “ON” cycles and
may result in the lowering of the temperature within the
conditioned space.
507295-02C Page 9 of 13mrcool.com
Operation
Cooling System
The cooling system is factory-charged with HFC-R-410A.
The compressor is hermetically sealed and base-mounted
with rubber-insulated bolts.
Cooling Sequence of Operation
When the thermostat calls for cooling, R is closed to Y (see
the wiring diagrams). This action completes the low voltage
control circuit, energizing the compressor, condenser fan
motor, and blower motor.
Unit compressors have internal protection. In the event there
is an abnormal rise in the temperature of the compressor,
the protector will open and cause the compressor to stop.
Cooling System Performance Values
Model
2 Ton 13
2.5 Ton 16
3 Ton 14
3.5 Ton 14
4 Ton 16
5 Ton 17
Based on outdoor ambient temperature of 82°F, and indoor
entering air of 80°F db, 67°F wb.
Suction
Superheat +/- 3°
Liquid
Subcooling +/- 2°
Table 3.
Blower Delay – Cooling
The circulating air blower is controlled by a timing circuit
in the integrated blower/ignition control. Timings are not
adjustable. Blower “ON” delay is 5 seconds after the
compressor starts and blower “OFF” timing is 60 seconds
after the compressor shuts down.
NOTE: There is no blower OFF delay when there is a call
for G (fan only).
Cooling System Performance
This equipment is a self-contained, factory-optimized
refrigerant system. The unit should not require adjustments
to system charge when properly installed. If unit
performance is questioned, perform the following checks.
Ensure unit is installed per manufacturer’s instructions and
for proper performance value. The indoor metering device
varies by model. When checking performance of a unit
value to judge performance. When checking performance
of a unit that uses an expansion valve for metering, refer
to the subcooling value to judge system performance. If
the measured performance value varies from table value
allowance, check internal seals, service panels and duct
work for air leaks, as well as restrictions and blower
speed settings. If unit performance remains questionable,
remove system charge, evacuate to 500 microns, and
weigh in refrigerant to nameplate charge. It is critical that
the exact charge is re-installed. Failure to comply will
compromise system performance. If unit performance is
still questionable, check for refrigerant-related problems,
such as blocked coil or circuits, malfunctioning metering
device or other system components.
Heating System
With the proper thermostat and sub-base, continuous
blower operation is possible by closing the R to G circuit.
Cooling blower delay is also functional in this mode.
Heating Sequence of Operation
When the thermostat calls for heating, R is closed to W. The
following describes the gas heating sequence of operation.
1. A call for heat from the room thermostat starts the
combustion air blower and the circulating air blower.
2. When the speed of the combustion air blower reaches
proper RPM, the pressure switch closes, initiating a
pre-purge period (30 seconds nominal).
3. When the pre-purge period has expired, the ignition
control energizes the main gas valve and spark
electrode for a period of 10 seconds.
4.
been established in the 10-second interval, then the
ignition control will de-energize the gas valve, and
begins a 30 second inter-purge period, then initiates
another trial for ignition.
5. The ignition control is designed to repeat this “trial
for ignition” a total of three times. If, at the end of the
ignition control will try to light again 1 hour later. The
reset by interrupting the unit power or the thermostat
circuit.
6.
air blower is energized after a 30 second blower on
delay.
7.
blower and gas valve are de-energized. The circulation
air blower will continue to run for a short period after
the furnace is shut down.
Page 10 of 13 507295-02Cmrcool.com
Blower OFF Delay – Heating
• The circulating air blower “OFF” delay is 120 seconds
after shutting down the burners. This delay is not
adjustable.
• The circulating air blower “ON” delay is 120 seconds
after “W” signal is received to allow the furnace to
warm up.
Safety Controls
The control circuit includes the following safety controls:
Limit Control
This control is located inside the heating compartment
and is designed to open at abnormally high circulating
air temperatures. It resets automatically. The limit control
operates when a high temperature condition, caused by
Pressure Switch
If the combustion air blower should fail, the pressure
switch prevents the spark electrode and gas valve from
being energized.
Maintenance
Periodic inspection and maintenance normally consists of
coil. On occasion, other components of the furnace may
also require cleaning.
WARNING
Shut off all electrical power to the unit before conducting
any maintenance procedures. Failure to do so could
cause personal injury.
Filters
Filters are not supplied with the unit. Inspect once a month.
Replace disposable or clean permanent type as necessary.
Do not replace permanent type with disposable.
Motors
Indoor and outdoor fan and vent motors are permanently
lubricated and require no maintenance.
Flame Sensor
If the ignition control does not receive a signal from the
ignition period.
Rollout Switch
The switch is located on the top of the burner box. In the
event of a sustained main burner rollout, the rollout switch
shuts off the ignition control and closes the main gas valve.
To reset, push the button on top of the switch.
Secure Owner’s Approval
When the system is functioning properly, secure the owner’s
approval. Show the owner the location of all disconnect
switches and the thermostat. Instruct the owner on how
to start and stop the unit and how to adjust temperature
settings within the limitations of the system.
Indoor fans are equipped with a permanent magnet
constant torque motor. These motors remain energized and
are controlled by 24V signals. For high static applications,
use Tap 3 for cooling speed and Tap 5 for heating speed.
Outdoor Coil
Dirt and debris should not be allowed to accumulate on
the outdoor coil surface or other parts in the air circuit.
Cleaning should be as often as necessary to keep coil
clean. Use a brush, vacuum cleaner attachment, or other
suitable means. If water is used to clean the coil, be sure
the power to unit is shut off prior to cleaning. Care should
not damaged.
Do not permit the hot condenser air discharge to be
obstructed by overhanging structures or shrubs.
Burners
section. Vacuum and/or brush as required.
Vent Outlet
Visually inspect vent outlet periodically to make sure that
there is no buildup of soot or dirt. If necessary, clean to
507295-02C Page 11 of 13mrcool.com
Heat Exchanger
With proper combustion adjustment, the heat exchanger
of a gas appliance is highly irregular and once cleaned,
the cause of the sooting must be determined. If the heat
exchanger should become sooted, it can be cleaned as
follows:
1. Remove the burner assembly as outlined in the Burner
2. Remove the combustion blower.
3. At the bottom of the heating section, remove the screws
collector box without ripping the adjacent insulation.
4.
inside of each heat exchanger from the burner inlet
Control System Diagnostics
LED Status Flashing Rate Fault Description
Slow Flash
Fast Flash
2 Flash
3 Flash 1.5 seconds with
4 Flash
second
second
second with
1-second pause
1-second pause
2 seconds with
1-second pause
Normal operation:
No call for heat
Normal operation:
Call for heat
System lockout:
Failed to detect or
Pressure switch senses
incorrect pressure or gas
valve coil is open.
High limit or rollout
switch open
5.
6. Run the wire brush down the heat exchanger tubes
7. If soot buildup is excessive, remove the vent motor and
clean the wheel and housing. Run the wire brush down
8. After brushing is complete, blow all brushed areas with
5 Flash
Steady --
2.5 seconds with
1-second pause
Table 4. Fault Codes
Flame sensed and gas
valve not energized
Internal failure:
Micro-controller failure;
self-check
air. Vacuum as needed.
9. Replace parts in the reverse order they were removed
in Steps 1 through 3.
10.
not to tear the adjoining insulation.
11. Assure that all joints on the vent side of the combustion
system are air tight. Apply a high temperature (+500°F)
sealing compound where needed.
Table 5. Cooling Performance - Gas/Electric Models
80 DB / 67 WB Deg.
Return Air
Cooling
Input
(1000 BTU)
24
30 135 137 140 142 143 145 147 150 152 154 155 157
36 135 137 140 142 143 144 147 149 151 152 154 155
42 129 132 135 139 140 141 143 145 146 147 148 149
48 132 136 139 143 144 145 146 147 149 151 152 154
60 130 131 133 134 135 136 139 141 144 146 149 152
24
30 247 269 292 314 323 336 358 380 406 432 457 483
36 250 275 301 326 336 351 375 399 423 446 470 493
42 248 271 293 316 325 339 362 385 411 436 462 487
48 265 286 308 329 338 352 376 400 427 455 482 509
60 256 276 296 316 324 340 365 386 415 438 473 503
Pressure 65° 70° 75° 80° 82° 85° 90° 95° 100° 105° 110° 115°
135 136 137 139 139 141 143 146 148 150 152 154
Suction
250 266 282 298 304 318 340 363 388 413 438 463
Liquid
Air Temperature Entering Outdoor Coil, Degree F
Page 12 of 13 507295-02Cmrcool.com
LINE VOLTAGE FIELD INSTALLED
S4
S1
A3
GV1
S18
S47
S10
B6
B4
K1-2
C12
B1
K1-1
A3
E1
S79
S173
P1-11
P1-12
208/230-1-60
POWER SUPPLY WITH MIN.
C COPPER WIRE
75
HR1
(IF USED)
HEATER
CASE
CRANK
BLK
COMPRESSOR
CONTACTOR
L2
FAN MOTOR
T2
GRY
CONDENSER
BLK W/ WHT
BLK W/ WHT
PRESSURE
J1: PLUG THROUGH CONTROL PANEL (12 PIN)
ONLY, MIN 75
SWITCH
GAS VALVE
NOTE:
IF ANY OF THE ORIGINAL
WIRE IS REPLACED THE
SAME SIZE AND TYPE WIRE
MUST BE USED.
USE COPPER CONDUCTOR
COMPRESSOR
RED
5 FLASH Flame sensed and gas valve not energized.
STEADY Internal failure (micro-controller failure; self check)
R
YEL
H
C
ORG
J1-2
J1-1
J1-3
BLOWER
AIR
WHT
BLK W/ WHT
ROLLOUT
SWITCH
4 FLASH Main limit open or rollout switch open.
SWITCH
WHT
FLAME SENSE
SLOW FLASH Normal operation, no call for heat.
FAST FLASH Normal operation, call for heat.
3 FLASH Pressure switch senses incorrect pressure,
aux. limit is open or gas valve coil is open
C WIRE
BLK
S
C
BLK
CAPACITOR
F
T1
DUAL
COMPRESSOR
CONTACTOR
L1
PUR
BLK
BLK
BLK
COMB.
BLK
GRN
N
LIMIT
MAIN
WHT
W/ RED
The following ignition control board LED codes will
indicate normal or abnormal operations:
BRN
BRN
PUR
PUR
BLU
RED
INDOOR
BLOWER
MOTOR
L
24V
GRN
C
Y
YEL
BLK
TRANSFORMER
GROUND
LED
G
W
WHT
GRN
BLU
FUSE
B3
208V
240V
T1
BLU
1
6 2 5
3
4
FLAME
SPARK
DRK BLU
BLK
BLK
RED
24VAC
IGNITION CONTROL
R
WHT
RED
L1
IGNITION CONTROL
CMB BLWR
ACB
COOL
ACB
HEAT
LOW PRESSURE SWITCH
(IF USED)
BLU
THERMAL PROTECTION
SWITCH (IF USED)
CONTACTOR
KI
SINGLE PHASE
BLU
HIGH PRESSURE
SWITCH
YEL
5
4
3
2
1
NOTE: TAP 1 FOR FAN ONLY
TAP2: COOLING
TAP3: HIGH STATIC COOLING
TAP4: HEATING
TAP5: HIGH STATIC HEATING
GAS/ELECTRIC (CONSTANT TORQUE BLOWER)
CONNECTION DIAGRAM
BLOWER MOTOR TERMINAL BLOCK
N
G L C
WARNING-
ELECTRIC SHOCK HAZARD. UNIT
MUST BE GROUNDED IN ACCORDANCE
WITH NATIONAL AND LOCAL CODES.
537659-01
Figure 8. Wiring Diagram – Single Phase CT
507295-02C Page 13 of 13mrcool.com
FLOAT SWITCH (IF USED)
GRN
YEL
GRN
WHT
RED
Y G
W1
R
C
CONTROL CIRCUIT
WIRING TO BE 24 VOLT,
N.E.C. CLASS 2
THERMOSTAT
HEAT ANTICIPATION SETTING: 0.75 AMP
Signature Series
MPG*S*M414A Residential Package
ELECTRICIAN and /or HVAC TECHNICIAN:
LICENSE #:
INSTAL LATION DAT E:
INSTALLATION LOCATION:
SERIAL NUMBER:
The design and specifications of this product and/or manual are subject to change without prior notice.
Consult with the sales agency or manufacturer for details.
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