Why does my lasko 5842 model keep kicking off and I keep the filter clean

Answer is in instructions
Save-Smart®
Press () to activate the Save-Smart®Function.
1.Set the thermostat to desired temperature using the +/-
buttons (Note: The default Save-Smart®temperature is 72 ? F)
2.When you reach the temperature at which you want to
set the unit, the set temperature will flash several times
and then the display will return to indicate the current
room temperature and will gradually change as the
room temperature changes.
3.When the air temperature is less than the set temperature,
the heater will run in HIGH heat.
4.Once the thermostat reaches the set temperature the heater
will automatically switch to LOW heat to save energy.
5.When the air temperature reaches 4? above the set temperature,
the heater will turn off. The Heater will cycle off and on in the LOW
mode to maintain the set temperature.
All this happens automatically with Lasko Save-Smart®Technology.
To deactivate the Save-Smart®function, press Save-Smart®
again or (hi/lo) for continuous high/low heat.

AUTOMATIC TEMPERATURE CONTROL(Figure 3)
The automatic temperature function will only operate on "High" heat.
You cannot set the temperature automatically when the unit is in the low heat mode.
1.To set the room at a specific temperature press the () or()buttons
to the desired temperature. The display will now reflect the () and the temperature will be flashing. The Heater is now in Auto Temperature Mode.
2.When you reach the temperature at which you want to set the unit, the set temperature will flash several times and then the display will return to indicate the current room temperature and will gradually change as the room temperature changes. NOTE: the temperature display does not indicate the temperature of the heated air being emitted by the heater.
3.Once the room temperature reaches 2 degrees above the set temperature, the Heater will shut off. Once the room temperature reaches 1 degree below the set temperature, the Heater will turn back on and continue to cycle off and on to maintain the set temperature.
4.This function will cancel if the ()button is pressed. The Heater will now be in High heat and run continuously.
NOTE:It is normal for the Heater "fan" to run for approximately 15 seconds when the Heater shuts off after reaching the set temperature.Press the () and() buttons at the same time to change the display to ° Celsius. Press the same two buttons together again to change the display
back to ° Fahrenheit.