TWO SPEED | FAN | TWO SPEED | ||||||
THERMOSTAT | COIL | HEAT PUMP | ||||||
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W2 |
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| CONTROL |
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| W3 |
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| LOGIC |
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| W3 |
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| A93572 |
PRESSURE SWITCH PROTECTION
The outdoor unit is equipped with high- and
Fig. 36—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
EMERGENCY HEAT
If the
COMPRESSOR PTC-OVERLOAD PROTECTION
The control senses the resistance of the compressor internal
TABLE 16—COMPRESSOR PTC RANGES
COMPRESSOR
Safe Range (77°F) | 1.5k to 7.8k ohms |
To trip | 26k to 34k ohms |
To reset | 8.4k to 10k ohms |
When the control turns off the outdoor unit due to
III. FACTORY DEFAULTS
Factory defaults have been provided in the event of failure of the ambient thermistor,
IV. MAJOR COMPONENTS
TWO-SPEED CONTROL
The
•High- and
•Outdoor
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•Compressor protection
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•Time delays
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Heat pumps:
•Time/temperature defrost
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•Furnace interface
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HEADER-PIN HOUSING
The
TWO-SPEED COMPRESSOR
The
The
TABLE 17—FACTORY DEFAULTS
FAILED COMPONENT | FUNCTION | DEFAULT | |
| Crankcase Heater | Energized during any off cycle | |
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| Does not function | ||
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| Balance point does not function, but | |
| Furnace Interface | interface still energizes furnace and | |
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| locks out heat pump with a call for W2 | |
Ambient Thermistor | Heating Switchover Speed Point | Unit only runs in high- | |
| compressor speed | ||
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| Defrost Initiation | Defrost is initiated based on coil | |
| temperature only | ||
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| Outdoor Thermostat for | Anytime there is a call for W2, | |
| Auxiliary Heat | W3 is also energized. | |
Outdoor Coil Thermistor | Defrost Initiation and Termination | Defrost occurs at each time interval, | |
but terminates after 5 minutes | |||
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Furnace Interface Jumper | Furnace Interface | Does not function | |
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