5. AC/HP TIME DELAY (GRY) - Four motor operation delay
options are provided to customize system operation. See
listing below:
Unit Controls— All compressors have the following internal-
protection controls.
1. High-Pressure Relief Valve - This valve opens when the
pressure differential between the low and high side becomes
excessive.
2. Compressor Overload - This overload interrupts power to
the compressor when either the current or internal tempera-
ture become excessive, and automatically resets when the
internal temperature drops to a safe level.
This overload may require up to 60 minutes (or longer) to
reset; therefore, if the internal overload is suspected of
being open, disconnect the electrical power to the unit and
check the circuit through the overload with an ohmmeter or
continuity tester.
I.
COOLING SEQUENCE OF OPERATION
PSC BLOWER MOTOR UNITS (024–042)
NOTE: With the FAN switch in the ON position, 24-v is supplied
to the IFR through the G terminal on the thermostat. This voltage
energizes the coil of the contactor, closing the normally-open set of
contacts which provide continuous power to the indoor (evapora-
tor) fan motor (IFM). Moving the FAN switch back to the AUTO.
position, providing there is not a call for cooling, deenergizes the
IFR, opens the IFR contacts, and deenergizes the IFM. The FAN
switch in AUTO. position cycles upon a call for cooling.
On a call for cooling, 24 v is supplied to the compressor contactor
(C) and IFR simultaneously through the Y and G terminals of the
thermostat, respectively. On units with a compressor time delay
relay, there is a built-in, 5-minute (± 45 seconds) delay between
compressor starts. Energizing the contactor closes the normally-
open set of contacts supplying power to both the compressor and
outdoor (condenser) fan motor (OFM). Energizing the IFR closes
the normally-open set of contacts providing power to the IFM. On
the loss of the call for cooling, 24 v is removed from both the Y
and G terminals of the thermostat (providing the FAN switch is in
the AUTO. position), deenergizing both the contactor and IFR and
opening both the contacts supplying power to compressor/OFM
and IFM.
ECM BLOWER MOTOR UNITS (048–060)
Indoor Fan - With the fan switch in the ON position, 24-v is
supplied to the ECM motor through the ’’G’’ terminal on the
thermostat. This voltage provides continuous power to the indoor
(evaporator) fan motor (IFM). If the fan switch is moved back to
the AUTO position and there is not a call for heating or cooling,
24-v is removed from the ’’G’’ terminal and the indoor fan
TABLE 5—TERMINAL CONFIGURATION
TERMINAL
1
2
3
4
Available
Airflow (CFM)
1365
1470
1680
1840
Fig. 29—Easy Select Interface Board for Units 048-060 with ECM Blower Motor
C95024
AUX HEAT
RANGE
VIO
1
2
3
4
BLU
1
2
3
4
AC/HP SIZE
BRN
AC
HPC
H P
TYPE
BLK
LO
MED
H I
AC/HP CFM ADJUST
GR Y
AC/HP TIME DELAY
1
2
3
4
RED
JW1
JW2
D4
D5
P1
1
W3
W2
E
/W
1
G
Y1 Y /Y2
O
C
R
L
1
P2
JW3
Y1
G
W2
Y/Y2
JW 4
JW 5
R1
R2
R3
IFO
O
SEC-1
SEC-2
L
D3
D1
D2
F1
5 AMP FUSE
5
TABLE 6—CFM ADJUST (PERCENT OF CFM)
MODE
FAN ONLY
COOLING
HEATING
LO-Adjust
–15
–10
–10
HI-Adjust
15
10
10
—22—
