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11-Low Ambient Kit Relay (K58)
Low ambient relay K58 is a DPDT relay with a 24V coil ener
gized by a CMC1 output in the heating cycle. K58-1 closes
to allow power to reversing valves L1 and L2. K58-2 closes
to bypass S11 and S84. This allows the fan to operate dur
ing the heating demand and cycle during the cooling de
mand.
12-Blower Motor Overload Relay Switch
(S42)
The blower motor overload relay is used in all units
equipped with high efficiency motors. The relay (S42) is
connected in line with the blower motor to monitor the cur
rent flow to the motor. When the relay senses and overload
condition, a set of normally closed contacts open to de-en
ergize 24VAC power T1 transformer.
13-Terminal Block (TB1)
TB1 provides 24VAC field connections. All indoor ther
mostat connections are connected to TB1 located in the
control box.
14-Compressor Overload Relays S176, S177
(M-volt CE units)
Relays are wired in series with the appropriate compres
sor contactor and monitor the current flow to the compres
sor motor. When the relay senses an overload condition,
N.C. contacts open to de-energize the compressor. Re
lays are manufactured by Siemens; see figure 5.
15-Enthalpy Control (A6)
Refer to description in economizer section.
FIGURE 5
COMPRESSOR OVERLOAD RELAYS
SET RELAYS
TO MAXIMUM
OVERLOAD
SETTING
