Page 32
10−Blower Contactor K3 (all units)
Blower contactor K3, used in all units, is a three-pole-double-
break contactor with a 24VAC coil used to energize the indoor
blower motor B3 in response to blower demand. K3 is ener-
gized by main control panel (A55).
11−Outdoor Fan Relay K10, K68, K149, K150,
K152, K153
Outdoor fan relays K10, K68, K149, K150, K152 and K153
used in all units, are DPDT relays with a 24VAC coil. In all
units, K10 (energized by A55) K68 (eneregized by A57),
K149, K150, K152 and K153 (energized by A59) energize
condenser fans B4 (fan 1), B5 (fan 2), B21 (fan 3), B22 (fan
4), B23 (fan 5) and B24 (fan 6) respectively, in response to
thermostat demand. On all units condenser fans B4, B5 and
B21 energize on first stage cool demand (Y1). Condensr fans
B22, B23 and B24 energize on second stage cool demand
(Y2). On 360H units with three compressors, condenser fans
B4, B5, B21, B22, B23 and B24 energize on first stage cool
demand (Y1).
12−Combustion Air Inducer Relay K13
(LGA/LGC units − first burner section)
Combustion air inducer relay K13, used in all LGA and LGC
units, is a DPDT relay with a 24VAC coil. K13 is energized by
the main control module A55 after a first stage heating de-
mand from the thermostat. K13 remains energized through-
out the heating demand. When energized, K13 N.O. con-
tacts close to energize combustion air blower and begin a
heating sequence. Prove switch S18, located in the com-
pressor compartment, closes as combustion air static
pressure falls to prove" combustion air inducer opera-
tion. When S18 closes, the ignition controls and gas
valves are energized to begin a heating sequence.
13−Combustion Air Inducer Relay K19
(LGA/LGC units − second burner section)
Combustion air inducer relay K19, used in all LGA and LGC
units, is a DPDT relay with a 24 VAC coil. K19 is energized by
the gas valve control module A58 after a first stage heating de-
mand from the thermostat. K19 remains energized through-
out the first stage heating demand. When energized, K19
N.O. contacts close to energize the second heat section com-
bustion air inducer and begin second section heating se-
quence. Prove switch S45, located in the compressor
compartment, closes as combustion air static pressure falls to
prove" combustion air inducer operation. When S45 closes,
the second section of the ignition control and gas valve are
energized to begin the second section heating sequence.
14−Burner Controls A3 & A12 (LGA units)
All LGA and LGC units have two burner controls. A3 controls
gas heat section one, while A12 controls gas heat section two.
The first gas heat section and the second gas heat section
burner controls are identical. Both burner controls are factory
set and are not adjustable. The control makes three attempts
at ignition and then locks out the system if ignition is not ob-
tained after the third trial. Reset after lockout requires only
breaking and remaking thermostat demand. The control
shuts off gas flow immediately in the event of a gas or pow-
er failure. Upon restoration of gas and power, the control
will restart the ignition sequence and continue until flame
is established or system locks out. For a more detailed de-
scription see the Gas Heat Components section.
15−Power Exhaust Relay K65 (PED units)
Power exhaust relay K65 is a N.O. DPDT relay with a
24VAC coil. K65 is used in all LGA/LGC/LCA/LCC units
equipped with the optional power exhaust dampers.
K65 is energized by the economizer control panel (A56),
after the economizer dampers reach 50% open (adjust-
able in ECTO). When K65 closes, the exhaust fans B10,
B11 and B12 are energized.
16−Blower Motor Overload Relay S42 (units
with high efficiency motors & standard
efficiency motors of 7.5 HP and above)
The blower motor overload relay is used in all L series units
equipped with high efficiency motors, as well as units with
standard efficiency motors 7.5 HP and higher. The relay (S42)
is connected in line with the blower motor to monitor the cur-
rent flow to the motor. When the relay senses an overload con-
dition, a set of normally closed contacts open to de−energize
pin #9 in plug 110 of the A55 main control module. A55 de−en-
ergizes all outputs. Early model units have been equipped with
a control manufactured by Telemecanique which is detailed in
figure 5. Units built after November 21, 1997, are equipped
with a relay manufactured by Siemens which is detailed in fig-
ure 6. 7.5 HP motors used in units built after late 1998, will
have an internal overload relay.
To Next Page
Loading...
Need help?
General
