Factory Defaults; Major Components - Carrier R-22 Application Manual And Service Manual

balance-point POT. (See Fig. 36.) Temperatures that may be
selected are 10°, 15°, 20°, 25°, 30°, 35°, 40°, and 45°F. The POT
is factory-set at 45°F.
LOW-SPEED HEATING WITH AUXILIARY HEAT
If the system is operating in low-speed heating and there is a
demand for auxiliary heat (W2), the system changes to high-speed
operation. W2 is energized unless the low-voltage control wiring is
configured as described in Fig. 38.
TWO SPEED
THERMOSTAT
W2
Fig. 38—Low-Voltage Control Wiring
AUXILIARY HEAT (W2) LOCKOUT
In some areas, it is necessary to disable the auxiliary heat, except
for defrost, until the outdoor ambient is less than the structure's
balance point. This is accomplished by using the low-voltage
wiring as shown in Fig. 38. Wire the 24vac W2 signal from the
indoor thermostat to W3 of the control, and W2 of the control to
W2 of the indoor unit. When the outdoor ambient is less than the
setting of the balance-point POT, the 24vac signal energizes the
auxiliary heat (W2) of the indoor unit.
EMERGENCY HEAT
If the 2-speed control receives a call for auxiliary heat (W2)
without a heat-pump heating (Y1) call, the second auxiliary stage
(W3) is energized. This ensures all available heat is energized if
the indoor thermostat is switched to emergency heat.
COMPRESSOR PTC-OVERLOAD PROTECTION
The control senses the resistance of the compressor internal
positive-temperature coefficient (PTC) overloads. If the resistance
of the PTCs is out of range, the control shuts off the unit until the
resistance range is acceptable. See Table 17 for compressor PTC
ranges.
Table 17—Compressor PTC Ranges
COMPRESSOR INTERNAL-PTC RESISTANCE
Safe Range (77°F)
To trip
To reset
When the control turns off the outdoor unit due to out-of-range
PTCs, the unit remains off for 15 minutes with the outdoor fan
running. After 15 minutes, the control checks the resistance every
5 minutes until it reaches the reset range. During this time, a
malfunction signal appears on the control board. If this happens,
remove the wires on control board at S1 and S2 and measure the
resistance across the leads. When the resistance reaches 8,400 to
10,000 ohms, system operation may be resumed. If the resistance
remains outside this range, a quick check of the leads at the
compressor should be made. Loose connections can cause inaccu-
rate readings. If a PTC trip occurs 3 times, the control will lock out
the outdoor-unit operation and provide malfunction signals at both
the control and indoor thermostat.
PRESSURE SWITCH PROTECTION
FAN TWO SPEED
COIL HEAT PUMP
W2 W2
CONTROL
W3
LOGIC
W3
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1.5k to 7.8k ohms
26k to 34k ohms
8.4k to 10k ohms
The outdoor unit is equipped with high- and low-pressure
switches, wired in series. If a pressure switch opens, the control
provides a 5-minute time delay in outdoor unit operation with the
outdoor fan running. A malfunction signal appears on the control
when a pressure switch opens. If the switch remains open for 1 hr
or longer, a malfunction signal is provided at the L terminal of the
indoor thermostat.
Step 3—Factory Defaults
Factory defaults have been provided in the event of failure of the
ambient thermistor, outdoor-coil thermistor, and/or furnace inter-
face jumper. Refer to Table 18 for default and function.
Step 4—Major Components
TWO-SPEED CONTROL
The 2-speed control board controls the following functions:
• High- and low-compressor contactor operation
• Outdoor fan-motor operation
• Crankcase-heater operation
• Compressor protection
• Pressure-switch monitoring
• Second-stage latching
• Time delays
• 5-minute time-delay speedup (bypass)
Heat pumps:
• Time/temperature defrost
• Defrost-interval selection
• Furnace interface
• Electric-heat staging
HEADER-PIN HOUSING
The header-pin housing is the plastic assembly which holds the
stripped-lead ends for field connections. The 2-speed control
receives the 24vac low-voltage control-system inputs through the
housing/pins. The housing also contains jumpers which the control
uses for system configuration, such as heat pump versus air
conditioner. See Fig. 39 for header-pin housing configurations.
TWO-SPEED COMPRESSOR
C - TRANSFORMER COMMON
1
R - TRANSFORMER LINE
2
3
4
W2 - FIRST STAGE AUXILIARY HEAT
5
O - REVERSING VALVE
6
Y2 - SECOND STAGE COOLING/HEAT PUMP
7
Y1 - FIRST STAGE COOLING/HEAT PUMP
8
W3 - SECOND STAGE AUXILIARY HEAT
9
L - MALFUNCTION LIGHT
10
11
4 - TON
12
13
5 - TON
14
15
16
17
JUMPER FOR
HEAT PUMP ONLY
18
Fig. 39—Header-Pin Housing
34
IF NO JUMPER IS
INSTALLED, DEFAULT
IS 3 - TON
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