3DJH
TABLE 1
BLOWER CONTROL A15 TERMINAL DESIGNATIONS
Terminal
(Designa-
tion on Wir-
ing
Diagram)
Type
Function
Y
Detachable
or Screw
Strip
Cooling Demand
G
Detachable
or Screw
Strip
Blower Demand
R
Detachable
or Screw
Strip
24VAC to Thermostat
W
Detachable
or Screw
Strip
Heating Demand
T
Detachable
or Screw
Strip
24VAC Common
To Indoor Thermostat
IBN (N)
1/4
Spade
120VAC Indoor Blower Common
N1 (N)
1/4
Spade
120VAC Neutral
(L2 Line Voltage Neutral)
CABN (N)
1/4 Spade
120VAC Combustion Air Blower
Common
XFMRN (N) 1/4 Spade
120VAC Transformer Common
HSIN (N)
1/4 Spade
120VAC Hot Surface Ignition
Common (Not Used)
CAB
1/4 Spade
Switched 120VAC to
Combustion Air Blower
L1
1/4 Spade
120VAC Line Voltage In
A
1/4 Spade
Switched 120VAC
to Blower Cooling Tap
XFMR
1/4 Spade
24VAC In From Transformer
D
1/4 Spade
Dummy Connection for
Unused Blower Leads
CF
1/4 Spade
Switched 120VAC to
Continuous Blower Tap
H
1/4 Spade
Switched 120VAC to
Blower Heating Tap
ACC
1/4 Spade
Switched 120VAC to Accessory
(Electronic Air Cleaner, Humidifier,
Etc.)
24V
(24)
3/16 or
1/4 Spade
24VAC Input From Transformer
LIMIT
(L)
1/4 Spade
24VAC In From Primary Limit. Limit
Open: Closes Gas Valve and Turns
On Blower Limit Closed: Allows
Ignition
W
1/4 Spade
24VAC Thermostat Demand Output
Through Rollout and Prove Switch
to TH Terminal of Ignition Con-
trol
VALVE
SENSE (V)
3/16 or
1/4 Spade
24VAC Input From Gas Valve
T
1/4 Spade
24VAC Common From
Ignition Control and Gas Valve
COM (C)
1/4 Spade
24VAC Common To Transformer
C-Ignition Control (-1 Through -4 Models)
G23(X) -1, -2, -3 and -4 model units use an intermittent pilot
ignition control manufactured by Johnson Controls. The igni-
tion control is located on a bracket on the upper vest panel.
Unit Operation
When there is a call for heat, the control is prevented from
beginning an ignition sequence until the pressure switch
proves combustion air blower operation. When the pressure
switch closes, the control generates a spark and opens the
pilot valve to ignite the pilot. When flame is sensed, the con-
trol opens the main gas valve and the pilot ignites the main
burners. The indoor blower starts after a 45 second delay.
Gas valve remains open and combustion air blower contin-
ues to run until demand stops, flame sensor senses loss of
flame, a limit opens or the prove switch opens. If any of these
events occur during a thermostat demand, the gas valve
closes.
The control will attempt ignition for 85 seconds. If ignition is
not successful, the control will lockout (indicated by flash-
ing LED). Within one hour the control will momentarily re-
move then reapply the thermostat signal and the ignition
sequence will begin again (Watchguard circuit). If pilot
ignition is successful, but flame is lost when the main valve
opens, the ignition sequence will retry up to 15 more times.
If ignition is not successful after the 16th try, the control will
shut-down and must be reset manually. Manual reset is
accomplished by removing then reapplying thermostat
demand for at least 30 seconds.
FIGURE 11
IGNITION CONTROL A3
SPARK
OUTPUT
SEE TABLE 2
FOR TERMINAL
DESIGNATIONS
DANGER
Shock hazard.
Spark related components contain high voltage.
Disconnect power before servicing. Control is
not field repairable. If control is inoperable, sim-
ply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.