![background image](http://html.mh-extra.com/html/carrier/weathermaker-48a2020/weathermaker-48a2020_controls-start-up-operation-service-and-troubleshooting-instructions_2560305055.webp)
55
Table 56 — Staged Gas Heat Control Steps (
Configuration
HEAT
SG.CT
HT.ST
= 3)
Table 57 — Staged Gas Heat Control Steps (
Configuration
HEAT
SG.CT
HT.ST
= 4)
INTEGRATED GAS CONTROL BOARD LOGIC
All gas heat units are equipped with one or more integrated gas
control (IGC) boards. This board provides control for the igni-
tion system for the gas heat sections. On size 020-050 low heat
units there will be one IGC board. On size 020-050 high heat
units and 060 low heat units there are two IGC boards. On size
060 high heat units there are three IGC boards. When a call for
gas heat is initiated, power is sent to W on the IGC boards. For
standard 2-stage heat, all boards are wired in parallel. For
staged gas heat, each board is controlled separately. When en-
ergized, an LED on the IGC board will be turned on. See Table
58 for LED explanations. Each board will ensure that the roll-
out switch and limit switch are closed. The induced-draft mo-
tor is then energized. When the speed of the motor is proven
with the Hall Effect sensor on the motor, the ignition activation
period begins. The burners ignite within 5 seconds. If the burn-
ers do not light, there is a 22-second delay before another 5-
second attempt is made. If the burners still do not light, this se-
quence is repeated for 15 minutes. After 15 minutes have
elapsed and the burners have not ignited then heating is locked
out. The control will reset when the request for W (heat) is
temporarily removed. When ignition occurs, the IGC board
will continue to monitor the condition of the rollout switch,
limit switches, Hall Effect sensor, and the flame sensor. Forty-
five seconds after ignition has occurred, the IGC will request
that the indoor fan be turned on. The IGC fan output (IFO) is
connected to the indoor fan input on the MBB which will indi-
cate to the controls that the indoor fan should be turned on (if
not already on). If for some reason the overtemperature limit
switch trips prior to the start of the indoor fan blower, on the
next attempt the 45-second delay will be shortened by 5 sec-
onds. Gas will not be interrupted to the burners and heating
will continue. Once modified, the fan delay will not change
back to 45 seconds unless power is reset to the control. The
IGC boards only control the first stage of gas heat on each gas
valve. The second stages are controlled directly from the MBB
board. The IGC board has a minimum on-time of 1 minute. In
modes such as Service Test where long minimum on times are
not enforced, the 1-minute timer on the IGC will still be fol-
lowed and the gas will remain on for a minimum of 1 minute.
Table 58 — IGC LED Indicators
NOTES:
1. There is a 3-second pause between error code displays.
2. If more than one error code exists, all applicable error codes will be
displayed in numerical sequence.
3. Error codes on the IGC will be lost if power to the unit is inter-
rupted.
RELOCATE SAT (SUPPLY AIR TEMPERATURE) SENSOR
FOR HEATING IN LINKAGE APPLICATIONS
On CCN installations employing ComfortID™ terminals, the
factory SAT location must be changed to a new location down-
stream of the unit’s heating system. The ComfortID terminal
controls read the SAT value for their “proof-of-heat” sequence
before terminals open to Minimum Heating positions during
unit heating sequence.
Determine a location in the supply duct that will provide a fair-
ly uniform airflow. Typically this would be a minimum of
STAGE
RELAY OUTPUT
CAPACITY
%
Heat 1
Heat 2
Heat 3
Heat 4
Heat 5
Heat 6
MBB-RLY8
MBB-RLY7
SCB-RLY1
SCB-RLY2
SCB-RLY3
SCB-RLY4
IGC1
MGV1
IGC2
MGV2
IGC3
MGV3
0
OFF
OFF
OFF
OFF
OFF
OFF
0
1
ON
OFF
OFF
OFF
OFF
OFF
25
2
ON
ON
OFF
OFF
OFF
OFF
33
3
ON
OFF
ON
OFF
OFF
OFF
50
4
ON
ON
ON
OFF
OFF
OFF
58
5
ON
ON
ON
ON
OFF
OFF
67
6
ON
OFF
ON
OFF
ON
OFF
75
7
ON
OFF
ON
ON
ON
OFF
83
8
ON
ON
ON
ON
ON
OFF
92
9
ON
ON
ON
ON
ON
ON
100
STAGE
RELAY OUTPUT
CAPACITY
%
Heat 1
Heat 2
Heat 3
Heat 4
Heat 5
Heat 6
MBB-RLY8
MBB-RLY7
SCB-RLY1
SCB-RLY2
SCB-RLY3
SCB-RLY4
IGC1
MGV1
IGC2
MGV2
IGC3
MGV3
0
OFF
OFF
OFF
OFF
OFF
OFF
0
1
ON
OFF
OFF
OFF
OFF
OFF
19
2
ON
ON
OFF
OFF
OFF
OFF
25
3
ON
OFF
OFF
OFF
ON
OFF
38
4
ON
ON
OFF
OFF
ON
OFF
44
5
ON
ON
OFF
OFF
ON
ON
50
6
ON
OFF
ON
OFF
OFF
OFF
57
7
ON
ON
ON
OFF
OFF
OFF
63
8
ON
OFF
ON
OFF
ON
OFF
76
9
ON
OFF
ON
ON
ON
OFF
88
10
ON
ON
ON
ON
ON
OFF
94
11
ON
ON
ON
ON
ON
ON
100
LED INDICATION
ERROR CODE
On
Normal Operation
Off
Hardware Failure
1 Flash
Fan On/Off Delay Modified
2 Flashes
Limit Switch Fault
3 Flashes
Fame Sense Fault
4 Flashes
Five Consecutive Limit Switch Faults
5 Flashes
Ignition Lockout Fault
6 Flashes
Ignition Switch Fault
7 Flashes
Rollout Switch Fault
8 Flashes
Internal Control Fault
9 Flashes
Software Lockout
Summary of Contents for WEATHERMAKER 48A2020
Page 112: ...112 Fig 20 Typical Main Control Box Wiring Schematic 48 50A Units ...
Page 113: ...113 Fig 21 Typical Auxiliary Control Box Wiring Schematic ...
Page 114: ...114 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown ...
Page 115: ...115 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown TO NEXT PAGE ...
Page 116: ...116 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont ...
Page 117: ...117 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown ...
Page 118: ...118 Fig 25 Typical Controls Option Wiring Schematic SW1 SW2 OR DEHUMIDIFY SWITCH ...
Page 119: ...119 Fig 26 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown ...
Page 120: ...120 Fig 27 Typical Power Schematic of Greenspeed Low Ambient Option 48 50A 060 Unit Shown ...
Page 121: ...121 Fig 28 Typical Small Chassis Component Location Size 020 035 Units ...
Page 122: ...122 Fig 29 Typical Large Chassis Component Locations Size 040 060 Units ...
Page 185: ...185 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716 ...