Goodman GMEC80 Operating instructions

RS6621005
October 2019
This manual is to be used by qualied, professionally trained HVAC technicians only. Goodman does not as-
sume any responsibility for property damage or personal injury due to improper service procedures or services
performed by an unqualied person. The material in this manual does not supercede manufacturers installation
and operation instructions.
Copyright© 2019 Goodman Company, L.P.
Service Instructions
Goodman®Brand GMEC80/GCEC80
& Amana®Brand AMEC80/ACEC80
Two Stage Furnace
with multi-speed ECM Motor
®
is a registered trademark of Maytag Corporation or its related companies
and is under license to Goodman Company, L.P., Houston, TX, USA. All rights reserved.
®
Only personnel that have been trained to install, adjust, ser-

in this manual should service the equipment. The manufac-
turer will not be responsible for any injury or property dam-
age arising from improper service or servide procedures.
If you service this unit, you assume responsibility for any
injury or property damage which may result. In addition, in
jurisdictions that require one or more licenses to service the

should servise the equipment.
Improper installation, adjustment, servicing or repair of the
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manual without proper training may result in product dam-
age, property damage, personal injury or death.
WARNING
-
www.P65Warnings.ca.gov
PROP 65 WARNING
FOR CALIFORNIA CONSUMERS
0140M00517-A
WARN ING

2
IMPORTANT INFORMATION
Pride and workmanship go into every product to provide our customers with quality products. It is possible, however,
that during its lifetime a product may require service. Products should be serviced only by a qualied service technician
who is familiar with the safety procedures required in the repair and who is equipped with the proper tools, parts, testing
instruments and the appropriate service manual. REVIEW ALL SERVICE INFORMATION IN THE APPROPRIATE
SERVICE MANUAL BEFORE BEGINNING REPAIRS.
IMPORTANT NOTICES FOR CONSUMERS AND SERVICERS
RECOGNIZE SAFETY SYMBOLS, WORDS AND LABELS
TABLE OF CONTENTS
IMPORTANT INFORMATION ...............................2
PRODUCT IDENTIFICATION ..............................6
ACCESSORIES....................................................7
SYSTEM OPERATION. ........................................9
ACCESSORY WIRING DIAGRAMS ..................16
SERVICING ........................................................17
TROUBLESHOOTING .......................................20
SERVICING ........................................................23
MAINTENANCE .................................................35
WIRING DIAGRAMS ..........................................36
ELECTRICAL SHOCK, FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly could result in dan-
gerous operation, serious injury, death or property damage.
Improper servicing could result in dangerous operation, seri-
ous injury, death or property damage.
• Before servicing, disconnect all electrical power to
furnace.
• When servicing controls, label all wires prior to discon-
necting.
Reconnect wires correctly.
• Verify proper operation after servicing.
WARNING
FIRE, EXPLOSION OR CARBON MONOXIDE POISONING
HAZARD

explosion or carbon monoxide poisoning.
This appliance uses NEGATIVE PRESSURE REGULATED gas
control.

the manufacturer.
WARNING
RISQUE D'INCENDIE, D'EXPLOSION OU D'INTOXICATION AU
MONOXYDE DE CARBONE
Le remplacement de ce dispositif par une commande no
conforme risque de provoquer un incendie, un explosion ou
une intoxication au monoxyde de carbone.
Cet appareil utilise une commande de gaz À RÉGULATION DE
PRESSION NÉGATIVE.
La remplacer UNIQUEMENT par un dispositif portant le

fabricant.
RISQUE D'ÉLECTROCUTION, D'INCENDIE OU D'EXPLOSION
Si les consignes de sécurité ne sont pas suivies à la
lettre, cela peut entraîner la mort, de graves blessures, un
fonctionnement dangereux ou des dommages matériels.
Un entretien inadéquat peut entraîner la mort, de graves
blessures, un fonctionnement dangereux ou des dommages
matériels.
• 󰀨
débrancher de l'alimentation électrique.
• Avant l'entretien des commandes, étiqueter tous


• 
l'entretien.
AVERTISSEMENT
AVERTISSEMENT

3
IMPORTANT INFORMATION
gas. If you then smell gas, STOP!
above on this label.
Follow "B" in the safety information
above on this label. If you don't smell
8. Move the gas control switch or knob
9. Replace control access panel.
gas, go to the next step.
technician or gas supplier.
11. Set the thermostat to the desired
12. If the appliance will not operate,
To Appliance" and call your service
5. Replace control access panel.
to "OFF". Do not force.
follow the instructions "To Turn Off Gas
4. Move the gas control switch or knob
Do not store or use gasoline or
other flammable vapors and liquids in the vicinity of this
TO TURN OFF GAS TO APPLIANCE
10. Turn on all electric power to the
FOR YOUR SAFETY
or any other appliance.
2. Turn off all electric power to the
appliance if service is to be performed.
1. Set the thermostat to its lowest setting.
3. Remove control access panel.
automatic ignition system which
4. This appliance is equipped with an
3. Turn off all electric power to the
2. Set the thermostat to lowest setting.
5. Remove control access panel.
try to light the burners by hand.
6. Move the gas control switch or knob
automatically lights the burners. Do not
to "OFF".
appliance.
setting.
appliance.
to "ON".
0140F00001P
SWITCH SHOWN
IN "ON" POSITION
GAS CONTROL
Force or attempted repair may result in
FOR YOUR SAFETY READ BEFORE OPERATING
call the fire department.
damage, personal injury or loss of life.
If you cannot reach your gas supplier,
a fire or explosion may result causing property
If you do not follow these instructions exactly,
which has been under water.
C. Use only your hand to move the gas
control switch or knob. Never use
tools. If the gas control switch or knob
D. Do not use this appliance if any part
has been under water. Immediately call
a qualified service technician to inspect
the appliance and to replace any part of
the control system and any gas control
7. Wait five (5) minutes to clear out any
will not operate, don't try to repair it,
call a qualified service technician.
is heavier than air and will settle on the
Immediately call your supplier
the gas suppliers instructions.
WHAT TO DO IF YOU SMELL GAS
Do not try to light any appliance.
Do not touch any electric switch;
do not use any telephone in your
from a neighbor's phone. Follow
1. STOP! Read the safety information
OPERATING INSTRUCTIONS
floor.
building.
a fire or explosion.
try to light the burners by hand.
smell next to the floor because some gas
the appliance area for gas. Be sure to
B. BEFORE OPERATING smell around
automatically lights the burners. Do not
is equipped with an ignition device which
A. This appliance does not have a pilot. It
This product contains
Fiberglass insulation.
instructions and local
If notWARNING:
in fuel combustion
you to substances
death or serious
which can cause
Illness.
accordance with the
and maintained in
instructions, this
product could expose
manufacturer's
installed, operated
For outdoor
PGB & PGJ
For indoor installation.
of local codes, follow
codes. In the absence
Code, ANSI Z223.1.
the National Fuel Gas
installation only.
cause injury or
consult a qualified
Refer to the user's
information manual
provided with this
property damage.
This furnace must be
or the gas supplier.
alteration, service or
maintenance can
WARNING: Improper

4
CONSIGNES DE SECURITE - LIRE
AVANT D'ALLUMER L'APPAREIL
AVERTISSEMENT: Le non-respect des instructions qui suivent peut
entrainer un risque d'incendie ou d'explosion causant des dommages,
des blessures ou la mort.
A. Cet appareil comporte pas de veilleuse. Il est muni d'un mecanisme qui allume
automatiquement le bruleur. N'allumez paz le bruleur manuellement.
B. Sentir tout autour de l'appariel AVANT D'ALLUMER afin de deceler toute fuite de gaz.
Assurez-vous de sentir tout pres du plancher car certains gaz sont plus lourds que l'air
et se deposeront sur le plancher.
SI VOUS SENTEZ UNE ODEUR DE GAZ:
Ne tentez d'allumer aucun appariel.
Ne touchez pas aux interrupteurs electriques; n'utiliser aucun telephone
dans l'edifice ou vous vous trouvez.
Appelez immediatement votre fournisseur de gaz en utilisant le telephone
d'un voisin et suivez les instructions du fournisseur.
Appelez les pompiers si vous ne parvenez pas a rejoindre votre fournisseur
de gaz.
C. N'utiliser que votre main pour pousser ou tourner le commande du gaz. N'utilisez
jamais d'outils. Si vous ne parvenez pas a pousser ou a tourner la commande, ne tentez
pas de la reparer; appelez un reparateur qualifie. Forcer la commande ou essayer de la
reparer peut entrainer un risque d'incendie ou d'explosion.
D. N'utilisez pas cet appareil si l'une de ses parties a ete dans l'eau. Si cela se produit,
demandez immediatement a un reparateur qualifie d'inspecter l'appareil et de remplacer
toute piece du systeme de controle et toute commande de gaz ayant ete dans l'eau.
0140F00002P
INSTRUCTIONS DE SERVICE
1. UN INSTANT! Lisez d'abord les consignes
2. Reglez le thermostat a son point le plus bas.
3. Coupez l'alimentation electrique de l'appareil.
4. Cet appareil est muni d'un mecanisme qui
allume automatiquement le bruleur. Ne tentez
pas d'allumer le bruleur manuellement.
5. Retirez le panneau d'acces de la commande.
6. Mettez la commande de gaz a la position
7. Attendez cinq (5) minutes afin de permettre a
tout gaz present d'etre evacue. Si vous sentez
une odeur de gaz a ce moment, ARRETEZ! et
suivez les consignes de securite donnees au
de gaz, passez a l'etape suivante.
8. Mettez la commande de gaz a la position
en place.
10. Retablissez l'alimenation electrique de l'appareil.
11. Reglez le thermostat a le temperature desiree.
12. Si l'appareil ne fonctionne pas, suivez les
instructions intitulees "Arret du gaz" et appelez un
reparateur qualifie ou votre fournisseur de gaz.
ARRET DU GAZ
1. Reglez le thermostat a son point le plus bas.
2. Coupez l'alimentation electrique de l'appareil si vous devez effectuer un entretien.
3. Retirez le panneau d'acces de la commande.
4. Mettez la commande de gaz a la position ARRET ("OFF").
5. Remettez le panneau d'acces de la commande en place.
de securite ci-dessus.
ARRET ("OFF").
paragraphe B ci-dessus. Si vous ne sentez pas
MARCHE ("ON").
9. Remettez la panneau d'acces de la commande
^^
^
^
^
^
^
^
^
^
^
^
^
Commande de
"MARCHE"
gaz en position

5
IMPORTANT INFORMATION
To locate an authorized servicer, please consult your telephone book or the dealer from whom you purchased this
product. For further assistance, please contact:
CONSUMER INFORMATION LINE
GOODMAN®BRAND PRODUCTS
TOLL FREE
1-877-254-4729 (U.S. only)
email us at:
[email protected]
fax us at: [phone]
(Not a technical assistance line for dealers.)
CONSUMER INFORMATION LINE
AMANA® BRAND PRODUCTS
TOLL FREE
1-877-254-4729 (U.S. only)
󰀨
com
fax us at: [phone]
(Not a technical assistance line for dealers.)
Outside the U.S., call 1-713-861-2500.
(Not a technical assistance line for dealers.) Your telephone company will bill you for the call.
B10259-2 16
CO can cause serious illness including permanent brain
damage or death.
Advertencia especial para la instalación de calentadores ó manejadoras
de aire en áreas cerradas como estacionamientos ó cuartos de servicio.
B10259-216
El monóxido de carbono puede causar enfermedades severas
como daño cerebral permanente ó muerte.
Las emisiones de monóxido de carbono pueden circular a través
del aparato cuando se opera en cualquier modo.
B10259-216
RISQUE D'EMPOISONNEMENT AU MONOXYDE DE CARBONE
Le monoxyde de
des
carbone peut causer des maladies graves telles que
dommages permanents au cerveau et meme la mort.
au CO pouvant survenir si un appareil produisant du monoxyde

PRODUCT IDENTIFICATION
6
The model and manufacturing number are used for positive identication of component parts used in manufacturing.
Please use these numbers when requesting service or parts information.
A M E C 8 0 0 6 0 3 B N A A
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Brand Minor Revision
A- Amana A - Initial Release
G - Goodman B - 1st Revision
Configuration
M - Upflow/Horizontal Major Revision
C - Downflow/Horizontal A - Initial Release
K - Dedicated Upflow B - 1st Revision
D - Dedicated Downflow
Nox
Motor N - Natural Gas
V - Variable Speed X - Low NOx
E - High Efficiency
S - Single Speed Cabinet Width
A - 14"
Gas Valve B - 17.5"
M - Modulating C - 21"
C - 2 Stage D - 24.5"
H - Convertible 2 Stage
S - Single Stage Maximum CFM
3 - 1200 CFM
AFUE 4 - 1600 CFM
80 - 80% AFUE 92 - 92% AFUE 5 - 2000 CFM
96 - 96% AFUE 97 - 97% AFUE
MBTU/h
030 - 30,000 BTU/h 080 - 80,000 BTU/h
040 - 40,000 BTU/h 100 - 100,000 BTU/h
060 - 60,000 BTU/h 120 - 120,000 BTU/h
Furnace Nomenclature (14 Digits)

ACCESSORIES
7
ACCESSORY DESCRIPTION
AFE18-60A
Fossil Fuel Kit. The AFE18-60A control is designed for use where the indoor coil is located above/downstream
of a gas or fossil fuel furnace when used with a heat pump. It will operate with single and two stage heat
pumps and single and two stage furnaces. The AFE18-60A control will turn the heat pump unit off when the
furnace is turned on. An anti-short cycle feature initiates a 3 minute timed off delay when the compressor goes
off.
AM11-5RA
Merv 11 Media Air Cleaner The Clean Comfort™ AM11-5RA Series of MERV 11 media air cleaners for
residential applications helps remove a wide range of airborne particles as small as 0.3 micron. Extra deep,
5¼ inch pleated filter with long filter life and low static pressure. Helps protect and prolong the operating
efficiency of the heating and cooling equipment. Space saving design for vertical installations, reduces
installation space by 6-8 inches. Eliminates the need for a 90° duct adapter, as it works as a turning vane
providing even distribution across the media filter. Includes MERV 11 media filter, rated at 492 feet/minute,
removes airborne particles down to 0.3 micron. Heavy-gauge, galvanized-steel cabinet and powdercoat paint
finish on one of the cabinet cabinet doors resist corrosion and provide trouble-free installation
AM11-45
Merv 11 Media Air Cleaner The Clean Comfort™ AM11-5RA Series of MERV 11 media air cleaners for
residential applications helps remove a wide range of airborne particles as small as 0.3 micron. Includes
MERV 11 media filter, rated at 492 feet/minute. Includes 4 1/2 inch pleated filter. Dual gasketed door for proper
air seal. Filter frame designed with dual pull tabs for easy removal.
AMP-BSRB
Bottom / Side Return Air Base Clean Comfort™ Upflow Bottom Side Return Base for gas furnaces. designed
with outer dimensions that match the furnace to lift the unit off the floor and allow for increased air flow in a
vertical installation by allowing bottom cabinet return air as well as side return air. When installed with a Clean
Comfort CleanFit™ media air cleaner, these bases expand filtered airflow. Solid one-piece wrapped cabinet
made from 20 gauge steel for support and durability. Available in A, B, C, D cabinet widths.
AMHP-250-UPD
Whole-House HEPA Air Cleaner This Clean Comfort™ product offers five stages of air treatm ent for
outstanding cleaning and sterilization of air in the home. The AMHP-250-UPD combines HEPA particulate
filtration, non-ozone producing UVC germicidal light for deactivation of viruses, bacteria and molds,
photocatalytic oxidation for reduction of airborne chemicals, and activated carbon / potassium permanganate
odor absorption -all in one air treatment system. Powerful European motor delivers up to 250 CFM of pure air,
without adding static pressure to the HVAC system. Long-life, HEPA media filter removes 99.97% of all
airborne particles 0.3 micron (1/84,000 of an inch) and larger
AMHP-300-GT
Whole-House Duct Mount HEPA Air Cleaner. The Clean Comfort® AMHP-300-GT Duct Mount HEPA bypas s air
cleaner uses True HEPA media material that is certified to remove 99.97% of all particles as small as 0.3
microns (1/84,000 of an inch) from a home's air. It also helps remove odors, such as those from cooking,
smoking or painting with the Carbon VOC Prefilter.The MERV 8 prefilter with activated carbon helps remove lint
to prolong the life of HEPA filter and unpleasant odors, such as those from cooking, smoking, painting or other
household activities. Since the AMHP-300-GT is installed in a bypass configuration, it does not add static
pressure to the HVAC system
AE14-5
Whole-House Electronic Air Cleaner The Clean Comfort AE14 Series of Electronic Air Cleaners for residential
applications helps remove a wide range of airborne particles as small as 0.01 micron (0.01 micron =
1/2,540,000 of an inch). Types of particles removed include atmospheric and household dust, coal dust,
insecticide dust, mites, pollen, mold spores, fungi, bacteria, viruses, pet dander, cooking smoke and grease
and tobacco smoke.
AE14-GM
High Efficiency Return Grille-Mount Electronic Air Cleaner The Clean Comfort™ High-Efficiency Return Grille-
Mount
Electronic Air Cleaner for residential applications helps remove a wide range of airborne particles as small as
0.06 micron (1/424,000 of an inch). Easily installs on the wall or ceiling in a ceiling box within trusses on 24-
inch centers without any
structural changes

ACCESSORIES
8
ACCESSORY DESCRIPTION
CFSB17
CFSB21
CFSB24
Counterflow Subbase Kit. For use with modulating 34.5" down flow furnace models. These kits are available
for the following furnace widths: 17.5" wide (CFSB17), 21" wide (CFSB21) and 24.5" wide (CFSB24). The kits
must be used to prevent excessive temperature from reaching combustible materials, if the furnace is installed
on a combustible floor. This subbase effectively separated the furnace base and plenum from combustible
materials. To ensure safe installation, do not install the counterflow floor base directly on carpeting, tile, or
other combustible material other than wood flooring.
DEHUM1
Dehumidistat. For use two-stage variable speed modulating furnace models. Wall mounted, 24 volt humidity
control available as a Dehumidistat used to reduce the airflow in the air conditioning mode when necessary to
lower the humidity in an occupied home to prevent dew build-up associated with high humidity levels. This
control features a moisture-sensitive nylon element and also provides positive ON-OFF settings for manual
operation. The control is a normally closed switch that opens on humidity rise causing the blower to switch to a
lower speed to control the humidity within the structure.
LPLP03
LP Gas Low Pressure Kit. Designed for application on furnaces converted to LP gas. The kit monitors gas line
pressure with a pressure switch and will open the circuit to the gas valve if the LP tank pressure gets low.
LPM-08
LP Conversion Kit Converts a 34.5" Two Stage furnace to operate on L.P. gas. The kit contains gas valve
springs for L.P. gas and a set of six L.P. 1.25 mm orifices. Includes instructions and a label to show the
furnace has been converted to L.P.
EFR0 1
External Filter Rack Kit. For use with Goodman® and Amana® Brand 80% upflow gas furnaces. This kit is
intended to provide a location, external to the furnace casing for installation of a permanent filter. The rack is
mounted over the indoor air blower compartment area of either side panel, and provide filter retention as well
as a location for attaching return air ductwork.

9
SYSTEM OPERATION
WARNING
I
F THE INFORMATION IN THESE INSTRUCTIONS IS NOT FOLLOWED EXACTLY, A
FIRE OR EXPLOSION MAY RESULT CAUSING PROPERTY DAMAGE, PERSONAL
INJURY OR LOSS OF LIFE.
–
D
O NOT STOREOR USEGASOLINE OR OTHER FLAMMABLE VAPORS AND
LIQUIDS IN THE VICINITY OFTHIS OR ANY OTHER APPLIANCE.
–
WHAT TO
DO
IF
YOU SMELL GAS
:
•
D
O NOT TRY TO LIGHT ANY APPLIANCE.
•
D
O NOT TOUCH ANY ELECTRICAL SWITCH; DO NOT USEANY
PHONE IN YOUR BUILDING.
•
I
MMEDIATELY CALL YOUR GAS SUPPLIER FROMANEIGHBOR’S
PHONE.
F
OLLOWTHE GAS SUPPLIER’S INSTRUCTIONS.
•
I
FYOUCANNOT REACH YOUR GAS SUPPLIER,CALL THE FIRE
DEPARTMENT.
–
I
NSTALLATIONAND SERVICE MUST BE PERFORMED BY AQUALIFIED INSTALLER,
SERVICE AGENCY OR THE GAS SUPPLIER.
ELECTRICAL CONNECTIONS
WARNING
T
O AVOID THE RISK OF ELECTRICAL SHOCK, WIRING TO THE UNIT MUST BE
PROPERLY POLARIZED AND GROUNDED.
WARNING
HIGH VOLTAGE
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR
INSTALLING THIS UNIT.
M
ULTIPLE POWER SOURCES MAY
BE PRESENT.
F
AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
CAUTION
L ABEL ALL WIRES PRIOR TO DISCONNECTION WHEN SERVICING CONTROLS.
W
IRING ERRORS CAN COUSE IMPROPER AND DANGEROUS OPERATION.
V
ERIFY PROPER OPERATION AFTER SERVICING.
WIRING HARNESS
The wiring harness is an integral part of this furnace. Field
alteration to comply with electrical codes should not be
required. Wires are color coded for identication purposes.
Refer to the wiring diagram for wire routings. If any of the
original wire as supplied with the furnace must be replaced,
it must be replaced with wiring material having a tempera-
ture rating of at least 105° C. Any replacement wiring must
be copper conductor.
115 VOLT LINE CONNECTIONS
Before proceeding with electrical connections, ensure that
the supply voltage, frequency, and phase correspond to
that specied on the unit rating plate. Power supply to the
furnace must be N.E.C. Class 1, and must comply with all
applicable codes. The furnace must be electrically ground-
ed in accordance with local codes or, in their absence, with
the latest edition of The National Electric Code, ANSI NFPA
70 and/or The Canadian Electric Code CSA C22.1.
An electrical disconnect must be provided at the furnace
location.
NOTE: Line polarity must be observed when making eld
connections.
Connect hot, neutral, and ground wires as shown in the
wiring diagram located on the unit’s blower door. Line
polarity must be observed when making eld connections.
Line voltage connections can be made through either the
right or left side panel.
The furnace is shipped congured for a right side (left side
for counterow) electrical connection with the junction box
located inside the burner compartment. To make electri-
cal connections through the opposite side of the furnace,
the junction box must be relocated to the other side of the
burner compartment prior to making electrical connections.
NOTE: Wire routing must not interfere with circulator blower
operation, lter removal, or routine maintenance.
WARNING
TO AVOID THE RISK OF ELECTRICAL SHOCK, INJURY, OR DEATH, THE
FURNACE MUST BE ELECTRICALLY GROUNDED IN ACCORDANCE WITH LOCAL
CODES OR, IN THEIR ABSENCE, WITH THE LATEST EDITION OF THE
NATIONAL ELECTRIC CODE.
115 VOLT LINE CONNECTION OF ACCESSORIES
(ELECTRONIC AIR CLEANER)
WARNING
HIGH VOLTAGE
D
ISCONNECT
ALL
POWER BEFORE SERVICING OR
CHANGING ANY ELECTRICAL WIRING.
M
ULTIPLE POWER
SOURCES MAY BE PRESENT.
F
AILURE TO DO SO MAY CAUSE
PROPERTY DAMAGE, PERSONAL INJURY OR DEATH.
Electronic
Air Cleaner
1.0 Amp maximum at 120 VAC
Humidifier 1.0 Amp maximum at 24 VAC
ACCESSORY LOAD SPECIFICATIONS
Turn OFF power to the furnace before installing any acces-
sories. Follow the humidier or air cleaner manufacturers’
instructions for locating, mounting, grounding, and con-
trolling these accessories.
If it is necessary for the installer to supply additional line
voltage wiring to the inside of the furnace, the wiring must
conform to all local codes, and have a minimum tempera-
ture rating of 105°C. All line voltage wire splices must be
made inside the furnace junction box.

10
SYSTEM OPERATION
The integrated control module electronic air cleaner ter-
minals (EAC) are energized with 115 volts whenever the
circulator blower is energized.
24 VOLT THERMOSTAT WIRING
NOTE: Low voltage connections can be made through
either the right or left side panel. Wire routing must not
interfere with circulator blower operation, lter removal, or
routine maintenance.
A 40 V.A. transformer and an integrated electronic control
are built into the furnace to allow use with most cooling
equipment. Consult the wiring diagram located in this
manual, the installation manual, or on the blower door for
further details of 115 Volt and 24 Volt wiring.
THERMOSTAT WIRING
The *MEC80 furnace has W1 & W2 terminals for connection
of a two stage heating thermostat. If desired, a thermostat
with only one stage of heat may be used. As shipped, the
furnace S1-1 switch is OFF; S1-2 switch is ON. This is the
correct position to use a single stage heating thermostat
with auto timing transition to high re.
R
YC
Furnace
Integrated
Control
Module
Remote Condensing Unit
(Single-Stage Cooling)
R
Thermostat - Single -Stage Heating with Single-Stage Cooling
NOTE: To apply a single-stage Heating Thermostat, the
thermostat selector switch on the Integrated Control Module
must be set on single-stage.
R
YC
Furnace
Integrated
Control
Module
Remote Condensing Unit
(Single-Stage Cooling)
R
Thermostat - Two-Stage Heating with Single-Stage Cooling
W1 W2
YFurnace
Integrated
Control
Module
Remote Condensing Unit
(Two-Stage Cooling)
Y2
W1 W2
Y2
Thermostat - Two-Stage Heating with Two-Stage Cooling
Thermostat Wiring Diagrams

A single-stage thermostat with only one heating stage
may be used to control this furnace. The application of a
single-stage thermostat o󰀨ers a timed transition from low
to high re. The furnace will run on low stage for a xed
period of time before stepping up to high stage to satisfy the
thermostat’s call for heat. The delay period prior to stepping
up can be set at either a xed 10 or 20 minute time delay
or a load based variable time between 1 and 12 minutes
(AUTO mode). If the AUTO mode is selected, the control
averages the cycle times of the previous three cycles and
uses the average to determine the time to transition from
low stage to high stage.
1 2 3 4
2 Stage Stat OFF OFF
1 Stg Stat 10 min delay ON OFF
1 Stg Stat 20 min delay ON ON
Auto
Off*ON*
90 OFF OFF
120 OFF ON
150
ON*OFF*
180 ON ON
*Factory Setting
Staging and Blower Off Delay Dip Switches PCBBF139
Heating Fan Off
Delay
S3
Dip Switch
Purpose
Switch Group
Function
Thermostat
setup
S3

Using the “TWIN” terminals and proper wiring enables
two *MEC80 furnaces of the same model and size to be
twinned. Twinning allows simultaneous operation of two
furnaces and forces the indoor blower motors of each fur-
nace to operate synchronously into a common duct system.
Using the twinning function will require only eld installed
wiring with no external kits or parts.
· The staging DIP switches and speed tap DIP switches
must be set the same on both furnaces.
NOTE: Each furnace must be connected to its own 115 VAC
power supply. The L1 connection toeach furnace must be
in phase (connected to circuit breakers on the same 115
VAC service panel phase leg). To verify that the furnaces
are in phase, check from L1 to L1 on each furnace with a
voltmeter. If the furnaces are in phase, the voltage between
both furnaces will be ZERO.
Room
Thermostat
Y2
Y
W
W2
R
G
C
Ylo
Y
W
W2
R
G
C
Ylo
Y
W
W2
R
G
C
Furnace 1 Furnace 2