17
During operaon the power to the circuit board is
controlled by a temperature sensor, which is clamped to
a feeder tube entering the outdoor coil. Defrost ming
periods of 30,60 and 90 minutes may be selected by
connecng the circuit board jumper to 30, 60 and 90
respecvely. Accumulaon of me for the ming period
selected starts when the sensor closes (approximately
31° F), and when the wall thermostat calls for heat. At the
end of the ming period, the unit’s defrost cycle will be
iniated provided the sensor remains closed. When the
sensor opens (approximately 75° F), the defrost cycle is
terminated and the ming period is reset. If the defrost
cycle is not terminated due to the sensor temperature, a
ten minute override interrupts the unit’s defrost period.
WARNING
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WARNING
WARNING
CAUTION
Preventive maintenance is the best way to avoid
unnecessary expense and inconvenience. Have this
system inspected at regular intervals by qualied service
personnel, at least twice a year. Routine maintenance
should cover the following items:
1. Tighten all belts, set screws, and wire connections.
2. Clean evaporator and condenser coils mechanically
or with cold water, if necessary. Usually any fouling
is only matted on the entering air face of the coil and
can be removed by brushing.
3. Lubricate motor bearings.
4. Align or replace belts as needed.
5. Replace lters as needed (see Filters section).
6. Check for blockage of condensate drain.
7. Check power and control voltages.
8. Check running amperage.
9. Check operating temperatures and pressures.
10. Check and adjust temperature and pressure controls.
11. Check and adjust damper linkages.
12. Check operation of all safety controls.
13. Check condenser fans and tighten set screws.
CAUTION
Every application may require a dierent frequency of
replacement of dirty lters. Filters must be replaced at least
every three (3) months during operating seasons.
Dirty lters are the most common cause of inadequate
heating or cooling performance. Filter inspection should be
made at least every two months; more often if necessary
because of local conditions and usage.
Dirty throwaway lters should be discarded and replaced
with a new, clean lter.
Disposable return air lters are supplied with this unit. See
the unit Specication Sheet or Technical Manual for the
correct size and part number. To remove the lters, remove
the lter access panel on return side of the unit.
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