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ically check for debris which may have collected around the
unit.
Heat Pump Operation
Your new Lennox heat pump has several characteristics
that you should be aware of:
Your heat pump satisfies heating demand by delivering
large amounts of warm air into the living space. This is quite
different from gas- or oil-fired furnaces or an electric fur-
nace which deliver lower volumes of considerably hotter air
to heat the space.
Do not be alarmed if you notice frost on the outdoor coil in
the winter months. Frost develops on the outdoor coil dur-
ing the heating cycle when temperatures are below 45°F
(7°C). An electronic control activates a defrost cycle lasting
5 to 15 minutes at preset intervals to clear the outdoor coil
of the frost. During the defrost cycle, you may notice steam
rising from the outdoor unit. This is a normal occurrence.
The thermostat may engage auxiliary heat during the de-
frost cycle to satisfy a heating demand; however, the unit
will return to normal operation at the conclusion of the de-
frost cycle.
Your Lennox HPXA12 heat pump is equipped with a com-
pressor crankcase heater which protects the compressor
from refrigerant slugging during cold weather operation. If
power to your unit has been interrupted for several hours
or more, set the room thermostat selector to the Emergen-
cy Heat" setting to obtain temporary heat without the risk
of serious equipment damage. In this operating mode, all
heating demand will be satisfied by auxiliary heat. Com-
pressor operation is locked out during Emergency Heat op-
eration. After a six-hour compressor crankcase heater
warm-up period, the thermostat can be switched to the
Heat" setting and normal operation will resume.
Thermostat Operation
Though your thermostat may vary somewhat from the de-
scription below, its operation will be similar.
Temperature Setting Levers
Most heat pump thermostats have two temperature selec-
tor levers: one for heating and one for cooling. Set the lev-
ers or dials to the desired temperature setpoints for both
heating and cooling. Avoid frequent temperature adjust-
ment; turning the unit off and back on before pressures
equalize puts stress on the unit compressor.
Fan Switch
In AUTO or INT (intermittent) mode, the blower operates
only when the thermostat calls for heating or cooling. This
mode is generally preferred when humidity control is a
priority. The ON or CONT mode provides continuous in-
door blower operation, regardless of whether the compres-
sor or auxiliary heat are operating. This mode is required
when constant air circulation or filtering is desired.
System Switch
Set the system switch for heating, cooling or auto opera-
tion. The auto mode allows the heat pump to automatically
switch from heating mode to cooling mode to maintain pre-
determined comfort settings. Many heat pump thermostats
are also equipped with an emergency heat mode which
locks out heat pump operation and provides temporary
heat supplied by the auxiliary heat.
Indicating Light
Most heat pump thermostats have an amber light which in-
dicates when the heat pump is operating in the emergency
heat mode.
Temperature Indicator
The temperature indicator displays the actual room tem-
perature.
Programmable Thermostats
Your Lennox system may be controlled by a programmable
thermostat. These thermostats provide the added feature
of programmable time-of-day setpoints for both heating
and cooling. Refer to the user’s information manual pro-
vided with your particular thermostat for operation details.
Preservice Check
If your system fails to operate, check the following before
calling for service:
Check to see that all electrical disconnect switches are
ON.
Make sure the room thermostat temperature selector is
properly set.
Make sure the room thermostat system switch is proper-
ly set.
Replace any blown fuses, or reset circuit breakers.
Make sure unit access panels are in place.
Make sure air filter is clean.
Locate and record unit model number before calling.
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