TM 9-4120-399-14
2-9. OPERATION IN LO HEAT MODE. In the LO HEAT mode three thermostatically
controlled heaters are activated. To operate the unit in LO HEAT mode perform the following
steps.
a. Turn mode selector switch to LO HEAT.
b. Turn temperature control thermostat knob as far as it will go in the INCREASE (warmer)
position.
NOTE
F o r faster warmer up, start unit in HI HEAT mode. In moderate
temperature, unit can then be switched back to LO HEAT.
c. When room or enclosure temperature reaches the desired level, slowly turn the temperature
control thermostat knob toward DECREASE (cooler). Heating will stop when you reach the
approximate room temperature. Further adjustment can be made by turning the temperature
control thermostat knob slightly toward INCREASE (warmer) or DECREASE (cooler) until
desired temperature is controlled automatically.
NOTE
Should unit fail to heat the room or enclosure to the desired temperature or
fail to maintain the desired temperature with temperature control thermostat
set in maximum INCREASE position, switch to HI HEAT.
d. Adjust fresh air damper (door) to desired setting. It is normally better to keep the fresh
air damper slightly open. Damper should be closed during very cold weather and during fast
warmup periods.
e. Adjust louvers to suit. Since warm air tends to rise, it is normally better to adjust the
conditioned air outlet louvers slightly downward. The conditioned air inlet louvers should be full
open.
NOTE
An overheat thermostat located near the heating elements will turn them
off if the temperature in the heater compartment reaches an excessive
level.
Three are thermostatically controlled. Three of these heater elements operate all of the time.
To operate the unit in the HI HEAT mode, perform the following steps.
a. Turn mode selector switch to HI HEAT.
b. Turn temperature control thermostat knob as far as it will go in the INCREASE (warmer)
position.
c. When room or enclosure temperature reaches the desired level, slowly turn the temperature
thermostat knob toward DECREASE (cooler). Make small adjustments until desired temperature
is maintained.
