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TYPICAL WIRING SCHEMATIC
LEGEND
AHA —
Adjustable Heat Anticipator
AWG —
American Wire Gage
C —
Contactor, Compressor
CAP —
Capacitor
CB —
Circuit Breaker
CC —
Cooling Capacitor
CH —
Crankcase Heater
COMP —
Compressor Motor
D —
Diode
DB —
Defrost Board
DFT —
Defrost Thermostat
EC —
Enthalpy Control
ECON —
Economizer
EPS —
Emergency Power Supply
(Nine-Volt Battery)
ER —
Economizer Relay
FSS —
Filter Status Switch
FPT —
Freeze-Up Protection Thermostat
FU —
Fuse
GND —
Ground
HC —
Heater Contactor (Strip Heat)
HPS —
High-Pressure Switch
HR —
Heater Relay
IFC —
Indoor-Fan Contactor
IFM —
Indoor-Fan Motor
LPS —
Low-Pressure Switch
LSM —
Limit Switch (Manual Reset)
MTR —
Motor
OAT —
Outdoor-Air Thermostat
OFM —
Outdoor-Fan Motor
P —
Plug
PL —
Plug Assembly
QT —
Quadruple Terminal
R —
Relay
RAT —
Return-Air Thermostat
RVS —
Reversing Valve Solenoid
SAT —
Supply-Air
Thermostat
ST —
Start Thermistor
SW1 —
Switch Fully Open
SW2 —
Switch Fully Closed
SW3 —
Switch Min.
Vent Position
SW4 —
Switch Max.
Vent Position
TB —
Terminal Block
TC —
Thermostat-
Cooling
TH —
Thermostat-
Heating
TRAN —
Transformer
Field Splice
Marked Wire
Terminal (Marked)
Terminal (Unmarked)
Terminal Block
Splice
Splice (Marked)
Factory Wiring
Field Control Wiring
Field Power Wiring
Accessory or
Optional Wiring
To indicate common
potential only. Not to
represent wiring.
NOTES:
1. If any of the original wire furnished
must be replaced, it must be
replaced with Type 90 C wire or its
equivalent.
2. Thermostat: HH07AT170, 172, 174.
Subbase: HH93AZ176.
3. Set heat anticipator at .8 amp for
first stage and .3 amp for second
stage.
4. Use copper conductors only.
5. Use copper, copper-clad aluminum
or aluminum conductors.
VOLTAGE
RATING
CB
MUST
TRIP
AMPS
MFG. PT. NO.
24V
POTTER &
BRUMFIELD
W28X-1024-3.2 3.2
6.
548F036-072
50TFQ004-012
548F036-120