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SPECIFICATIONS Magic-Pak: HW/HWC
2-30
SRM-HW/HWC 2/99
3. The unit continues cooling as long as both Y and G
are energized. When the cooling call is satisfied,
the circuit between Y, G and R is interrupted. The
contactor immediately opens, interrupting power to
the compressor and the outdoor cooling fan.
4. With the low voltage signal to terminal G on the
blower control board interrupted, the board starts
a countdown to blower “off”. After approximately 90
seconds, the cooling speed relay opens and the
circulating air blower shuts down (see note at the
end of this section).
Low Voltage
1. On a call for cooling, the thermostat closes the
circuit between R and terminals G and Y.
2. The 24-volt signal energizes terminal G on the
blower control board, starting the fan “on” timer.
After approximately 15 seconds, the relay closes
(see note at the end of this section). This sends line
voltage to the COOLING speed terminal on the
board, which starts the circulating air blower.
3. The signal from Y energizes the contactor, starting
the compressor and the outdoor cooling fan.
4. When the cooling call is satisfied, both G and Y de-
energize. The contactor opens immediately,
causing the compressor and the outdoor cooling
fan to stop.
5. The circulating air blower stops approximately 90
seconds after the G terminal on the blower control
board de-energizes (see note at the end of this
section).
FAN ON
Low Voltage
1. When the switch on the thermostat is moved to the
“FAN ON” position, a 24-volt signal is sent to the G
terminal on the blower control board.
2. With G energized, the blower control board starts
a countdown to fan “on”. Approximately 15 seconds
later (or immediately - see note at the end of this
section), the fan starts.
3. The blower control board closes a relay on the
board, sending line voltage to the terminal on the
board marked COOL. This starts the circulating
air blower.
4. When the switch at the thermostat is moved to the
“OFF” position, the 24-volt signal to the blower
control board is interrupted. With no signal at the
G terminal, the blower control board starts a
countdown to fan “off”. Approximately 90 seconds
later, a relay on the blower control board opens
(see note at the end of this section). This interrupts
the power to and stops the circulating air blower.
Note: Heatcraft blower control boards have a G “on”
delay of 15 seconds and an “off” delay of 90
seconds. Tridelta blower control boards have no
“on” time delay and a 60 -130 second “off” delay.