Allied A80UH1EX Series User manual

508031-02 Issue 2135 Page 1 of 29
SERVICE MANUAL
A80UH1EX & 80G1UHEX Gas Furnace
(P) 508031-02
*P508031-02*
Table of Contents
Technical Specications ..............................................2
Blower Performance....................................................3
Parts Arrangement.......................................................5
Unit Components.........................................................6
Placement and Installation ........................................16
Start-Up .....................................................................16
Heating System Service Checks ...............................16
Typical Operating Characteristics..............................20
Maintenance..............................................................21
Wiring and Sequence of Operation ...........................24
Troubleshooting: Heating Sequence of Operation ....26
Troubleshooting: Cooling Sequence of Operation.....28
Troubleshooting: Continuous Fan Sequence of
Operation...................................................................29
A80UH1EX & 80G1UHEX series units are mid-e󰀩ciency
gas furnaces used for upow or horizontal applications
only, manufactured with heat exchangers formed of
aluminized steel. A80UH1EX & 80G1UHEX units are
available in heating capacities of 40,000 to 100,000 Btuh
and cooling applications 2 to 5 tons. Refer to Engineering
Handbook for proper sizing.
A80UH1EX & 80G1UHEX model units are equipped with a
hot surface ignition system. The A80UH1EX & 80G1UHEX
units meet the new California 14 ng/J Nitrogen Oxides
(NOx) Standards and California Seasonal E󰀩ciency
requirements. All units use a redundant gas valve to assure
safety shut-o󰀨 as required by C.S.A.
All specications in this manual are subject to change.
Procedures outlined in this manual are presented as a
recommendation only and do not supersede or replace
local or state codes. In the absence of local or state codes,
the guidelines and procedures outlined in this manual
(except where noted) are recommended only and do not
constitute code.
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, be alert to
the potential for personal injury or death.
Electric shock hazard.
Can cause injury or death. Before attempting
to perform any service or maintenance,
turn the electrical power to unit OFF at
disconnect switch(es). Unit may have
multiple power supplies.
WARNING
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves
and protective clothing.
CAUTION
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a licensed professional HVAC installer (or
equivalent), service agency or the gas supplier.
WARNING

508031-02Issue 2135Page 2 of 29
Physical and Electrical Data
Model Input
(Btuh)
Output
(Btuh)
AFUE
(ICS)
Nominal
Cooling
Capacity
Gas
Inlet
(in.)
Volts/
Hz/
Phase
Max. Time
Delay
Breaker or
Fuse
Nominal
Full Load
Amps
Trans
(VA)
Approx
Shipping
Weight
(lbs)
A80UH1E040A12X
80G1UHE040A12X 40,000 32,700 80% 3 Ton 1/2 120-60-1 15 6.8 40 100
A80UH1E060A12X
80G1UHE060A12X 60,000 49,000 80% 3 Ton 1/2 120-60-1 15 6.8 40 113
A80UH1E080B16X
80G1UHE080B16X 80,000 70,500 80% 4 Ton 1/2 120-60-1 15 8.4 40 125
A80UH1E100C20X
80G1UHE100C20X 100,000 81,500 80% 5 Ton 1/2 120-60-1 15 10.9 40 149
NOTE: For vent length and clearances to combustibles, please reference installation instructions.
Accessory List
Catalog Number Description
External Filter Rack Kits
1.841018 1 Pack (16x25)
1.841039 10 Pack (16x25)
Return Air Base
68W61 14.5", A Width
68W62 17.5”, B Width
68W63 21.0”, C Width
Horizontal Suspension Kits
51W10 80 & 90% Kit
2-Stage Compressor Relay Kit
85W66 Blower Relay Kit
Twinning Kit
16W72 Constant Torque Gas Furnace Twinning Kit
High Altitude Pressure Switches (4501 - 7500 ft.)
20K91 -040 and -100 models only
Technical Specications

508031-02 Issue 2135 Page 3 of 29
A80UH1EX / 80G1UHEX 040A*12 Performance (less lter)
External
Static
Pressure
in. w.c.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1430 243 1200 140 1025 86 945 66 945 45
0.10 1395 253 1165 151 1005 99 940 75 930 50
0.20 1370 264 1130 157 930 99 825 80 795 68
0.30 1345 278 1100 170 895 110 775 85 650 63
0.40 1320 289 1085 182 875 120 745 90 615 70
0.50 1295 302 1035 189 820 126 705 102 545 76
0.60 1245 308 1010 200 795 135 655 107 515 85
0.70 1220 320 980 210 755 147 615 115 445 87
0.80 1200 332 930 215 700 152 570 121 400 95
A80UH1EX / 80G1UHEX 060A*12 Performance (less lter)
External
Static
Pressure
in. w.c.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1410 243 1190 141 1030 86 930 73 835 55
0.10 1380 251 1165 150 990 95 890 89 790 65
0.20 1360 264 1115 158 950 99 840 78 730 68
0.30 1315 278 1090 171 910 110 790 89 660 61
0.40 1295 290 1070 182 865 122 740 93 600 71
0.50 1270 300 1025 191 825 127 695 103 545 75
0.60 1235 300 1000 197 785 136 650 108 495 84
0.70 1215 317 975 208 750 147 615 118 450 88
0.80 1185 331 920 216 700 153 555 121 390 96
Blower Performance
A80UH1EX / 80G1UHEX 080B*16 Performance (less lter)
External
Static
Pressure
in. w.c.
Air Volume / Watts at Various Blower Speeds
High Medium-High Medium Medium-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 1785 344 1570 236 1455 183 1390 161 1230 116
0.10 1745 360 1535 249 1420 194 1360 172 1190 129
0.20 1725 373 1500 266 1375 212 1310 189 1145 135
0.30 1695 386 1475 279 1340 224 1280 201 1100 146
0.40 1665 405 1440 293 1305 237 1235 208 1065 156
0.50 1640 418 1410 307 1275 250 1190 223 1015 170
0.60 1595 433 1370 323 1235 263 1160 234 970 182
0.70 1570 446 1330 336 1190 277 1120 249 930 187
0.80 1530 461 1300 349 1155 289 1095 260 900 201

508031-02Issue 2135Page 4 of 29
A80UH1EX / 80G1UHEX 100C*20 Performance (less lter)
External
Static
Pressure
in. w.g.
Air Volume / Watts at Di󰀨erent Blower Speeds
Bottom Return Air, Side Return Air with Optional Return Air
Base, Return Air from Both Sides or Return Air from Bottom and
One Side.
Single Side Return Air − Air volumes in bold require eld fabricated
transition to accommodate 20 x 25 x 1 in. air lter in order to maintain
proper air velocity.
High Med-High Medium Med-Low Low High Med-High Medium Med-Low Low
cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts
0.00 2205 623 1950 415 1710 275 1575 220 1425 160 2235 595 1945 382 1725 262 1590 202 1430 165
0.10 2175 639 1910 427 1685 287 1545 234 1400 176 2205 611 1915 397 1695 280 1550 218 1400 193
0.20 2145 658 1885 449 1635 309 1490 246 1325 181 2165 629 1885 424 1660 293 1510 235 1335 175
0.30 2100 681 1845 466 1605 327 1465 259 1275 196 2135 652 1850 441 1615 312 1475 247 1275 182
0.40 2095 700 1815 481 1565 337 1415 280 1225 204 2085 676 1800 456 1580 330 1430 261 1240 197
0.50 2045 717 1780 499 1525 356 1375 286 1195 218 2055 685 1775 474 1535 347 1395 281 1195 206
0.60 2025 737 1735 516 1500 374 1350 304 1145 230 2025 700 1755 494 1505 359 1355 300 1155 222
0.70 1995 746 1715 533 1465 389 1320 323 1090 248 1990 720 1725 515 1480 377 1310 308 1120 237
0.80 1950 769 1675 547 1430 401 1255 331 1065 259 1965 742 1685 532 1445 396 1275 325 1060 248

508031-02 Issue 2135 Page 5 of 29
Parts Arrangement
Control Box
(includes integrated control,
interlock switch and transformer)
Blower Assembly
Power Choke
(4 and 5 Ton Only)
Heat Exchanger
Combustion Air Inducer
Gas Valve
Intake Air Elbow
A
ccess Panel
Intake Screen
Figure 1.

508031-02Issue 2135Page 6 of 29
Unit Components
A80UH1EX & 80G1UHEX unit components are shown
in Figure 1. The gas valve, combustion air inducer and
burners can be accessed by removing the upper access
panel. Electrical components are in the control box (Figure
2) found in the blower section.
Electrostatic discharge can a󰀨ect
electronic components. Take precautions
to neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
CAUTION
Control Transformer (T1)
A transformer located in the control box provides power
to the low voltage section of the unit. Transformers on all
models are rated 40VA with a 120V primary and a 24V
secondary.
Door Interlock Switch (S51)
A door interlock switch is wired in series with line voltage.
When the blower door is removed the unit will shut down.
NOTE: The door interlock switch is a safety switch. Do not
by-pass or jumper switch.
DOOR INTERLOCK
SWITCH (S51)
INTEGRATED IGNITION
CONTROL
(A92)
TRANSFORMER
(T1)
CIRCUIT
BREAKER
(CB8)
Figure 2. Control Box
Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box. The
switch provides overcurrent protection to the transformer
(T1). The breaker is rated at 3A at 32V. If the current
exceeds this limit the breaker will trip and all unit operation
will shutdown. The breaker can be manually reset by
pressing the button on the face.
Integrated Control (A92)
Shock hazard.
Disconnect power before servicing. Control is not eld
repairable. If control is inoperable, simply replace entire
control.
Can cause injury or death. Unsafe operation will result
if repair is attempted.
WARNING
The hot surface ignition control system consisting of
an integrated control (Figure 3 with control terminal
designations in tables 1, 2 and 3), sensor and ignitor
(Figure 6). The integrated control and ignitor work
in combination to ensure furnace ignition and ignitor
durability. The integrated control, controls all major furnace
operations. The integrated control also features a RED
LED for troubleshooting and two accessory terminals rated
at (1) one amp. See Table 4 for troubleshooting diagnostic
codes. The nitride ignitor is made from a non-porous, high
strength proprietary ceramic material that provides long life
and trouble free maintenance.
Electronic Ignition (Figure 4)
On a call for heat the integrated control monitors the
combustion air inducer pressure switch. The control will
not begin the heating cycle if the pressure switch is closed
(bypassed). Once the pressure switch is determined to
be open, the combustion air inducer is energized. When
the di󰀨erential in the pressure switch is great enough, the
pressure switch closes and a 15-second pre-purge begins.
If the pressure switch is not proven within 2-1/2 minutes,
the integrated control goes into Watchguard-Pressure
Switch mode for a 5-minute re-set period.
After the 15-second pre-purge period, the ignitor warms
up for 20 seconds during which the gas valve opens at
19 seconds for a 4-second trial for ignition. The ignitor
remains energized for the rst 3 seconds during the 4
second trial. If ignition is not proved during the 4-second
period, the integrated control will try four more times with
an inter purge and warm-up time between trials of 35
seconds. After a total of ve trials for ignition (including the
initial trial), the integrated control goes into Watchguard-
Flame Failure mode. After a 60-minute reset period, the
integrated control will begin the ignition sequence again.

508031-02 Issue 2135 Page 7 of 29
Figure 3. Integrated Control
(Automatic Hot Surface Ignition System)
Red LED
Recall Button
Blower Off Delay
Pin # Function
1Combustion Air Inducer Line
2Ignitor Line
3Combustion Air Inducer Neutral
4Ignitor Neutral
Table 1. 4-Pin Terminal Designation
Pin # Function
1High Limit Output
2Not Used
3 24V Line
4Not Used
5Rollout Switch Out
624V Neutral
7 High Limit Input
8Ground
9Gas Valve Common
10 Pressure Switch In
11 Rollout Switch In
12 Gas Valve Out
Table 2. 12-Pin Terminal Designations
1/4” Quick Connect Terminals
120HUM Humidier 120VAC
LINE 120VAC
XFMR Transformer 120VAC
CIRC Indoor blower 120VAC
EAC Indoor air quality accessory 120VAC
NEUTRALS Common 120VAC
HUM24 Humidier 24VAC
3/16” Quick Connect Terminals
COOL Cooling tap 24VAC
HEAT Heating tap 24VAC
FAN Continuous blower 24VAC
PARK (no power) Park terminal for speed taps
FS Flame sense
24 COM Common 24VAC
Table 3.

508031-02Issue 2135Page 8 of 29
Red LED Flash Code2Diagnostic Codes / Status of Furnace
O󰀨 No power to control or board fault detected
Heartbeat1Control powered - displayed during all modes of operation if no errors are detected
Continuous Rapid Flash Call For Heat / Burner Operation
1 ash Reverse line voltage polarity
2 ashes Improper earth ground
3 ashes Burner failed to light, or lost ame during heating demand
4 ashes Low ame signal - check ame sensor
5 ashes Watchguard - burner failed to light, exceeded maximum number or retries or recycles
6 ashes Control detected igniter circuit failure. Not available on all controls.
7 ashes Primary or secondary limit open or Watchguard mode - limit switch open longer than 3 minutes
8 ashes Rollout switch open
9 ashes Pressure switch failed to close of opened during heat demand
10 ashes Watchguard - pressure switch opened 5 times during one heat demand
11 ashes Pressure switch stuck closed prior to activation or combustion air inducer
12 ashes Flame sensed without gas valve energized
13 ashes Low line voltage
1 A “Heartbeat” is indicated by a “Slow Flash” - 1 sec on 1 sec o󰀨, repeating
2 Error codes are indicated by a “rapid ash” - the LED ashes X times at ½ second on ½ second o󰀨, remains o󰀨 for 3 seconds then
repeats.
Last 10 error codes are stored in memory including when power is shut o󰀨 to the unit. - To recall, press and release button, most
recent will be displayed rst, LED o󰀨 for 3 sec, then next error code is displayed, etc. To clear error codes, depress and hold button
longer than 5 seconds.
Table 4. Diagnostic Codes

508031-02 Issue 2135 Page 9 of 29
Demand
15
ON
OFF
CAI
34
1
Pre-Purge Ignitor Warm-up Blower
“On” Delay
Post
Purge
5 SEC
80
Ignitor
Gas Valve
Indoor Blower
38
Trial for
Ignition
* Blower on time will be 30 seconds after flame is sensed. Blower off time will depend on “OFF TIME” setting.
Figure 4. Electronic Ignition
Fan Time Control
Heating Fan On Time
The fan on time of 30 seconds is not adjustable.
Heating Fan O Time
Fan o󰀨 time (time that the blower operates after the heat
demand has been satised) can be adjusted by moving
the jumper to a di󰀨erent setting. The unit is shipped with
a factory fan o󰀨 setting of 90 seconds. For customized
comfort, monitor the supply air temperature once the heat
demand is satised. Note the supply air temperature at the
instant the blower is de-energized.
Adjust the fan-o󰀨 delay to achieve a supply air temperature
between 90° - 110° at the instant the blower is de-energized.
(Longer delay times allow for lower air temperature, shorter
delay times allow for higher air temperature). See Figure 5.
Cooling Fan On Time
The fan on time is 2 seconds and is not adjustable.
Cooling Fan O Time
The control has a 45 second fan o󰀨 delay after cooling
demand has been met. This delay is factory set and not
adjustable.
To adjust fan-off timing, reposition jumper across pins to
achieve desired setting.
NO JUMPER
60 90
120
180
60 90
120
180
60 90
120
180
60 90
120
180
60 Second
off Time
90 Second
off Time
120 Second
off Time
180 Second
off Time
Figure 5. Heat Fan O󰀨 Time in Seconds

508031-02Issue 2135Page 10 of 29
Thermal Switch (Figure 6)
The auto-reset switch is located on the front of the intake
air elbow. The switch will safely shut the unit down if
excessive temperatures are detected. When the switch
senses excessive temperature, the circuit breaks and the
ignition control immediately stops ignition and closes the
gas valve.
Primary Limit Control
The primary limit (S10) is located in the heating vestibule
panel. When excess heat is sensed in the heat exchanger,
the limit will open. If the limit is open, the furnace control
energizes the supply air blower and closes the gas valve.
The limit automatically resets when unit temperature
returns to normal. The switch must reset within three
minutes or the control will go into Watchguard for one
hour. The switch is factory set and cannot be adjusted. The
switch may have a di󰀨erent set point for each unit model
number.
Flame Sensor (Figure 6)
A ame sensor is located on the top of the air gas plenum.
The sensor can be removed for service without removing
the burner. During operation, ame is sensed by current
passed through the ame and sensing electrode. The
control allows the gas valve to remain open as long as
ame signal is sensed. To check ame sense signal use
the push-button found on the integrated control and go to
Field Test Mode. The menu will display the ame signal.
See Table 5 for ame signal.
Flame Signal in Microamps
Normal Low Drop Out
1.5 greater 0.5 - 1.4 0.4 or less
Table 5.
Gas Valve (Figure 6)
The valve is internally redundant to assure safety shut-o󰀨.
If the gas valve must be replaced, the same type valve
must be used.
24VAC terminals and gas control knob are located on the
valve. A wire harness connects the terminals from the gas
valve to the electronic ignition control. 24V applied to the
terminals energizes the valve. Inlet and outlet pressure
taps are located on the valve. A regulator adjustment screw
is located on the valve.
Air Gas Plenum
Burner
Gasket
Gas Manifold
Gas Valve
Air Orifice
Sensor
Ignitor
Gas Orifice
Thermal
Switch
(location)
Intake Air Screen
Intake Air
Elbow
Figure 6. Heating Components

508031-02 Issue 2135 Page 11 of 29
Combustion Air Inducer (B6)
All A80UH1EX & 80G1UHEX units use a combustion air
inducer to move air through the burners and heat exchanger
during heating operation. The blower uses a 120VAC
motor. The motor operates during all heating operation and
is controlled by integrated control A92. The inducer also
operates for 15 seconds before burner ignition (pre-purge)
and for 5 seconds after the gas valve closes (post-purge).
Combustion Air Inducer Prove Switch (S18)
A80UH1EX & 80G1UHEX series units are equipped with
a combustion air pressure switch (Figure 7) located near
the gas valve. The switch is connected to the combustion
air inducer housing by means of a exible silicone hose. It
monitors negative air pressure in the intake air elbow.
The switch is a single-pole single-throw proving switch
electrically connected to the furnace control. The
purpose of the switch is to prevent burner operation if
the combustion air inducer is not operating or if the ue
becomes obstructed.
On heat demand the switch senses that the combustion
air inducer is operating. It closes a circuit to the integrated
control when pressure inside the combustion air inducer
decreases to a certain set point. The pressure sensed by
the switch is negative relative to atmospheric pressure. If
the ue becomes obstructed during operation, the switch
senses a loss of pressure di󰀨erence and opens the circuit
to the furnace control and gas valve. See Table 6 for set
point.
NOTE: The switch is factory set and is not eld adjustable.
It is a safety shut-down control in the furnace and must
not be by-passed for any reason. If switch is closed or
bypassed, the control will not initiate ignition at start up.
Model Make in. w.c. Break in. w.c.
All 0.35 0.20
Table 6. Prove Switch Set Points
Positive +
to air intake pipe
Negative -
to air intake
elbow
Figure 7. Combustion Air Pressure Switch
Ignitor (Figure 6)
The ignitor is made of durable silicon nitride. Ignitor
longevity is enhanced by controlling voltage to the ignitor.
The integrated control provides a regulated 120 volts to the
ignitor for a consistent ignition and long ignitor life. Ohm
value should be 39 to 70.
See Figure 8 for resistance, and voltage check.
NOTE: The A80UH1EX & 80G1UHEX furnaces contain
electronic components that are polarity sensitive. Make
sure that the furnace is wired correctly and is properly
grounded.
Burner and Orice
Burners are factory set and require no adjustment. Always
operate the unit with air gas plenum in place. The burner
has one orice located between the gas valve and the air
intake assembly (Figure 6). To check or replace the orice
remove the intake air screen, coupling and intake air elbow.
Using a 5/8” socket, go through the elbow and unscrew the
gas orice. The burner uses an orice (see Table 7) that
is precisely matched to the burner input. The burner can
be removed for service. If burner has been removed, it is
critical to replace all gaskets.
Unit Input Orice Size
040 0.0595
060
080 0.0689
100 0.0810
Table 7. Gas Orice

508031-02Issue 2135Page 12 of 29
Test 1
Meter
(set to ohms)
Remove 5-pin plug from control
Check ohms reading across terminals 1and 5
Ohm value should be between 39 - 70.
Integrated control detail
.
Test 2
Seperate the 2-pin jack plug near the manifold
and check resistance of the ignitor. If the reading
is correct, then then there is a problem with the
wiring between the jack plug and control. If the
reading is not correct the issue is the ignitor.
Meter
(set to ohms)
Test 3
Insert meter probes into the terminals 1 and 5. (Use small
diameter probes in order to not damage plug). Check
voltage during 20 second warm up period. Voltage should
read 120 volts +10%. If voltage is above these values,
check for correct supply voltage to furnace.
Integrated control detail
Integrated control detail
Meter
(set to AC volts)
Figure 8. Heating Components

508031-02 Issue 2135 Page 13 of 29
Blower Motor
Each blower is statically and dynamically balanced as
an assembly before installation in the unit.
IMPORTANT
A80UH1EX & 80G1UHEX units are equipped with a
constant torque ECM motor. It has a DC motor coupled
to an electronic control module both contained in the
same motor housing. The motor is programmed to provide
constant torque at each of the ve selectable speed taps.
Each tap requires 24 volts to energize.
Input Voltage Requirements
The circuit is designed to be operated with AC voltage. To
enable a tap requires 12 to 33 VAC. Expected current draw
will be less than 20mA.
Troubleshooting the Motor
Troubleshooting the motor is an easy process. Follow
steps below.
1. Shut o󰀨 power to unit.
2. Remove input plugs P48 and P49 from motor. See
Figure 11 for troubleshooting procedure.
If correct voltage is present in tests 1 and 2 and motor is
not operating properly, replace motor. The motor is not eld
repairable.
If replacing the indoor blower motor or blower wheel is
necessary, placement is critical. The blower wheel must
be centered in the blower housing as shown in Figure 9.
When replacing the indoor blower motor the set screw
must be aligned and tightened with the motor shaft as
shown in Figure 10.
Center Blower Wheel
in Blower Housing
Figure 9. Blower Wheel Replacement
Set Screw
Housing Hub
Motor
Shaft
Figure 10. Align and Tighten Set Screw with Flat Side
of Motor Shaft

508031-02Issue 2135Page 14 of 29
1
2
3
4
5
C
L
G
N
Multi−Meter
(set to VAC)
P48
P49
120 120
Turn on power to unit. Check for 120 volts across terminals
“L” and “N” on input plug P48. If voltage is present, continue
upstream of plug P48; proceed to test 3.
1
2
3
4
5
C
L
G
N
Multi−Meter
(set to VAC)
P48
P49 24
Switch thermostat to CONTINUOUS FAN MODE. Check for
24 volts across terminal “C” on inpult plug P48and speed tap
used for continuous fan. (1, 2, 3, 4 or 5) on input plug P49. If
24 volts is not present problem may be up stream of plug P49.
Proceed to test 4.
Multi−Meter
(set to VAC)
120 120
24
Multi−Meter
(set to VAC)
problem is with the harness. If voltage is not present,
problem may be may be with the integrated control.
Check for 120 volts across terminals “CIRC” and “Neutrals”
on the integrated control. If voltage is present, problem is
with the harness. If voltage is not present problem may be
may be with the integrated control.
Test 1
Test 2
Test 3 (if necesssary)
Test 4 (if necessary)
to test 2. If voltage is not present, problem may be
Check for 24 volts across terminals “24 COM” and “FAN”
terminals on the integrated control. If voltage is present,
Figure 11.

508031-02 Issue 2135 Page 15 of 29
Replacing the Motor Module
1. Disconnect electrical power to unit.
2. Remove unit access panel.
3. Unplug the two harnesses from the motor control
module. See Figure 12.
TWO HARNESS
CONNECTIONS
MOTOR CONTROL MODULE
MOTOR
24VAC
24VAC
24VAC
24VAC
24VAC
T1
T2
T3
T4
T5
12345
CLGN
COM
INDUCTION L1
MODEL SPECIFIC
LINE VOLTAGE
GND
L2/N
Figure 12. Unplug the Two Harness Connection
4. Remove the two hex head bolts securing the motor
control module to the motor (see Figure 13).
REMOVE BOTH HEX
HEAD BOLTS
Figure 13. Remove the Hex Head Bolts
5. Slide the motor control module away from the motor
to access and disconnect the internal three wire
connector. It is not necessary to remove blower motor
itself. Set both hex head bolts aside.
Testing the Motor (Figure 14)
If any motor fails the below tests, do not install the new
control module. The motor is defective and it also must be
replaced. The new control can fail if placed on a defective
motor.
1. Using an ohmmeter check the resistance from any
one of the motor connector pins to the aluminum end
plate of the motor. This resistance should be greater
than 100k ohms.
2. Check the resistances between each of the three motor
connector pins. These should all read approximately
the same resistance within an ohm.
3. Check to see if the blower wheel spins freely.
Figure 14. Motor Test
Scale Measurement Range in Words ohms
2 M two megohm-two million ohms 0 - 2,000,000
200 K two hundred kilo-ohm-two
hundred thousand ohms
0 - 200,000
20 K twenty kilo-ohm-twenty thousand
ohms
0 - 20,000
2 K two kilo-ohm two-thousand ohms 0 - 2,000
200 two hundred ohms 0 - 200
Table 8.
Motor Module Installation
All replacement motor control modules look similar;
however, each module is designed for a specic motor
size. It is very important to make sure that you are using the
correct replacement motor control module. USE OF THE
WRONG MOTOR CONTROL MODULE MAY RESULT IN
UNEXPECTED UNIT OPERATION.
1. Verify electrical power to unit is disconnected.
2. Connect three-wire harness from motor to control
module.
3. Mount new motor control module to motor using two
hex head bolts removed in Figure 13. Torque bolts to
22 inch pounds or 1/16th clock turn as exampled to
the right.
12
3
4
5
6
7
8
9
10
11 12
1/16
TURN

508031-02Issue 2135Page 16 of 29
4. Reconnect the two harnesses to the motor control
module.
5. The electrical connectors of the motor should be
facing down to form a drip loop (Figure 15). This will
directs moisture away from the motor and its electric
connections on the motor.
CONNECTOR
ORIENTATION
BETWEEN 4 AND 8
O'CLOCK
BACK OF CONTROL
MODULE
DRIP LOOP
Figure 15. Drip Loop
Placement and Installation
Make sure unit is installed in accordance with installation
instructions and applicable codes.
Start-Up
Heating Start-Up
Shock and burn hazard.
A80UH1EX & 80G1UHEX units are equipped with a hot
surface ignition system. Do not attempt to light manually.
WARNING
Gas Valve Operation
Figure 16. Gas Valve
NEGATIVE AIR
PRESSURE PORT POSITIVE AIR
PRESSURE PORT
MANIFOLD
PRESSURE TAP
INLET OUTLET
SUPPLY
PRESSURE
TAP
GAS VALVE SHOWN IN THE ON POSITION
1. STOP! Read the safety information at the beginning
of this section.
2. Set the thermostat to the lowest setting.
3. Turn o󰀨 all electrical power to the unit.
4. This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the
burners by hand.
5. Remove the upper access panel.
6. Move gas valve switch to OFF position. Do not force.
See Figure 16.
7. Wait ve minutes to clear out any gas. If you then
smell gas, STOP! Immediately call your gas supplier
from a neighbor’s phone. Follow the gas supplier’s
instructions. If you do not smell gas go to next step.
8. Move gas valve switch to ON position. Do not force.
See Figure 16.
9. Replace the upper access panel.
10. Turn on all electrical power to the unit.
11. Set the thermostat to desired setting.
NOTE: When unit is initially started, steps 1 through
11 may need to be repeated to purge air from gas line.
12. If the appliance will not operate, follow the instructions
“Turning O󰀨 Gas to Unit” and call the gas supplier.
Turning O Gas to Unit
1. Set the thermostat to the lowest setting.
2. Turn o󰀨 all electrical power to the unit if service is to
be performed.
3. Remove the upper access panel.
4. Move gas valve switch to OFF position. Do not force.
See Figure 16.
5. Replace the upper access panel.
Safety or Emergency Shutdown
Disconnect main power to unit. Close manual and main
gas valves.
Extended Period Shutdown
Turn o󰀨 thermostat or set to “UNOCCUPIED” mode.
Close all gas valves (both internal and external to unit) to
guarantee no gas leaks into combustion chamber. Turn
o󰀨 power to unit. All access panels and covers must be in
place and secured.
Heating System Service Checks
C.S.A. Certication
All units are C.S.A. design certied without modications.
Refer to the A80UH1EX & 80G1UHEX Installation
Instruction.

508031-02 Issue 2135 Page 17 of 29
Gas Piping
Gas supply piping should not allow more than 0.5” w.c.
drop in pressure between gas meter and unit. Supply gas
pipe must not be smaller than unit gas connection.
Compounds used on gas piping threaded joints should be
resistant to action of liqueed petroleum gases.
Testing Gas Piping
If a exible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe shall
be installed at the gas valve and extend outside the
furnace cabinet.
CAUTION
In case emergency shutdown is required, turn o󰀨 the
main shut-o󰀨 valve and disconnect the main power to
unit. These controls should be properly labeled by the
installer.
IMPORTANT
Do not over torque (800 in-lbs) or under torque (350
in-lbs) when attaching the gas piping to the gas valve.
WARNING
When pressure testing gas lines, the gas valve must be
disconnected and isolated. Gas valves can be damaged if
subjected to more than 0.5 psig (14” w.c.). See Figure 17.
If the pressure is equal to or less than 0.5 psig (14” w.c.),
close the manual shut-o󰀨 valve before pressure testing to
isolate furnace from gas supply.
MANUAL MAIN SHUT-OFF VALVE
WILL NOT HOLD TEST PRESSURE
IN EXCESS OF 0.5 PSIG (14”W.C.)
GAS VALVE
CAP
FIELD PROVIDED
LINE PRESSURE TAP
Figure 17. Gas Piping Test Procedure
When checking piping connections for gas leaks, use
preferred means. Kitchen detergents can cause harmful
corrosion on various metals used in gas piping. Use of a
specialty Gas Leak Detector is strongly recommended.
Do not use matches, candles, ame or any other source of
ignition to check for gas leaks.
Gas Pressure Adjustment
Gas Flow (Approximate)
Model
Seconds for One Revolution
Natural Gas
1 cu ft Dial 2 cu ft Dial
-040 90 180
-060 60 120
-080 45 90
-100 36 72
Natural - 1000 btu/cu ft
Table 9. Gas Meter Clocking Chart
Furnace should operate at least 5 minutes before checking
gas ow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in
Table 9. If manifold pressure matches Table 10 and rate is
incorrect, check gas orices for proper size and restriction.
Remove temporary gas meter if installed.
NOTE: To obtain accurate reading, shut o all other gas
appliances connected to meter.
Supply and Manifold Pressure
Supply Pressure Measurement
A port on the inlet side of the gas valve provides access to
the supply pressure tap. Loosen the screws and connect
a manometer to measure supply pressure. The minimum
supply line pressure is 4.5” - 13.0” w.c. for natural and 11.0
- 13.0” w.c. for LP/Propane. Tighten after measurements
have been taken.
For safety, shut unit o󰀨 and remove manometer as soon
as an accurate reading has been obtained. Take care to
replace pressure tap plug.
IMPORTANT
Manifold Pressure Measurement
To correctly measure manifold pressure, follow the steps
below.
1. Remove the threaded plug from the outlet side of the
gas valve and install a eld-provided barbed tting.
Connect measuring device “+” connection to barbed
tting to measure manifold pressure.
Start unit and allow 5 minutes for unit to reach steady
state.

508031-02Issue 2135Page 18 of 29
2. After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in Table
18. Make manifold adjustment if necessary.
3. Shut unit o󰀨 and remove manometer as soon as an
accurate reading has been obtained.
4. Restart unit and check for any gas leaks. Seal any
leaks if found.
Altitude
Unit
Natural LP / Propane
Manifold Supply Manifold Supply
0 - 4,500 ft.
040 1.6 - 2.2
4.5 - 13.0
n/a n/a
060
3.0 - 3.8
3.4 - 3.8 11.0 - 13.0
080
100 n/a n/a
4,501 - 7,500 ft.
040 1.4 - 2.0
4.5 - 13.0
n/a n/a
060
2.5 - 3.3
2.5 - 3.3 11.0 - 13.0
080 n/a n/a
100 n/a n/a
Table 10. Supply Line and Manifold Pressure
(inches w.c.)
Proper Combustion
Furnace should operate a minimum 15 minutes with correct
manifold pressure and gas ow rate before checking
combustion. Take combustion sample beyond the ue
outlet and compare to Table 11. The maximum carbon
monoxide reading should not exceed 100 ppm.
Unit CO2% for Nat CO2% for LP LP Conversion
Kit
040
6.5 - 7.5
n/a n/a
060
7.5 - 9.0
20P40
080 20P41
100 n/a n/a
Table 11.
High Altitude
Units may be installed at altitudes up to 7,500 ft. above
sea level. See Table 10 for de-rate manifold values. Units
installed at altitude of 4,501 - 7,500 feet require a pressure
switch change which can be ordered separately. Table 12
lists pressure switch requirements at high altitude.
The combustion air pressure switch is factory-set and
requires no adjustment.
Unit
High Altitude Pressure Switch
(4,501 - 7,500 ft)
Natural LP/Propane
040 20K91 N/A
060 No Change No Change
080 No Change N/A
100 20K91 N/A
Table 12.

508031-02 Issue 2135 Page 19 of 29
Proper Ground and Voltage
A poorly grounded furnace can contribute to poor ame
sense signal. Use the following procedure to check for
ground and voltage to the integrated control.
1. Measure the AC voltage between Line Neutral (spade
terminals) and “C” terminal (low voltage terminal
block) on the integrated control. See Figure 18. A wide
variation in the voltage between Line Neutral and “C”
as a function of load indicates a poor or partial ground.
Compare the readings to Table 13. If the readings
exceed the maximum shown in Table 13, make repairs
before operating the furnace.
2. In addition, measure the AC voltage from Line Hot
to Line Neutral (spade terminals) on the integrated
control. See Figure 19. This voltage should be in the
range of 97 to 132 VAC.
Furnace Status Measurement VAC
Expected Maximum
Power On Furnace Idle 0.3 2
CAI / Ignitor Energized 0.75 5
Indoor Blower Energized Less than 2 10
Table 13.
CHECK VOLTAGE BETWEEN LINE NEUTRAL
AND LOW VOLTAGE “C” TERMINAL
Figure 18.
CHECK VOLTAGE BETWEEN LINE HOT
AND LINE NEUTRAL
Figure 19.

508031-02Issue 2135Page 20 of 29
Typical Operating Characteristics
Blower Operation and Adjustment
NOTE: The following is a generalized procedure and does
not apply to all thermostat controls.
1. Blower operation is dependent on thermostat control
system.
2. Generally, blower operation is set at thermostat
subbase fan switch. With fan switch in ON position,
blower operates continuously. With fan switch in
AUTO position, blower cycles with demand or runs
continuously while heating or cooling circuit cycles.
3. Depending on the type of indoor thermostat, blower
and entire unit will be o󰀨 when the system switch is in
OFF position.
Temperature Rise (Figure 20)
Temperature rise for A80UH1EX & 80G1UHEX units
depends on unit input, blower speed, blower horsepower
and static pressure as marked on the unit rating plate.
The blower speed must be set for unit operation within the
range of “TEMP. RISE °F” listed on the unit rating plate.
Supply Air
Return Air
TEMPERATURE RISE
Supply Duct Temperature
Return Duct Temperature _
Temperature Rise =
Figure 20.
External Static Pressure
1. Tap locations shown in Figure 21.
2. Punch a 1/4” diameter hole in supply and return air
plenums. Insert manometer hose ush with inside
edge of hole or insulation. Seal around the hose with
permagum. Connect the zero end of the manometer to
the discharge (supply) side of the system. On ducted
systems, connect the other end of manometer to the
return duct as above.
3. With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blower
motor speed to deliver the air desired according to the
job requirements. For heating speed external static
pressure drop must not be more than 0.5” w.c. For
cooling speed external static pressure drop must not
be more than 0.8” w.c.
4. Seal the hole when the check is complete.
EXTERNAL STATIC PRESSURE
Supply Duct Static
Return Duct Static +
Total Duct Static =
(dry coil)
Supply Air
Return Air -
+
or
High
Low
Figure 21.
Blower Speed Taps
Blower speed tap changes are made on the integrated
control. See Figure 3. The heating tap is connected to the
“HEAT” terminal and the cooling tap is connected to the
“COOL” terminal. The continuous blower tap is connected
to the “FAN” terminal. Unused taps must be secured on
dummy terminals labeled “PARK.” To change out existing
speed tap, turn o󰀨 power and switch out speed tap with tap
connected to “PARK.” See blower speed tap table on unit
diagram for motor tap colors for each speed.