7.8 Defrost Thermostat
The defrost thermostat is attached to the refrigerant suction tube
between the accumulator and the compressor. It will automatically
shut the compressor off if the low side refrigerant temperature
drops due to excessive frost formation on the evaporator coil.
The fan will continue to run, causing air to flow through the
evaporator coil and melt the ice. When the ice has melted, the
evaporator temperature will rise and the thermostat will restart the
compressor.
7.9 Electric Ventilation Damper
The electric ventilation damper is controlled by the ventilation timer.
The damper will open when the ventilation timer is activated to allow
fresh air into the structure through the 6" diameter fresh air inlet duct.
The electric ventilation damper will remain closed when the ventilation
timer is not activated to prevent over-ventilating the structure when
the unit is dehumidifying or recirculating the indoor air.
The electric ventilation timer operates on 24 Vac from the control
circuit. DO NOT connect high voltage to the damper motor or
damage to the motor may result. DO NOT force the blade of the
damper by hand or damage to the damper motor may result.
The damper opens in one direction only. The damper rotates very
slowly, allow sufficient time for the damper to cycle. The damper
will take approximately 1 minute to cycle from closed to open or
from open to closed.
If the electric ventilation damper fails to operate:
1. Check that the wiring is correct and that voltage is present at
the damper motor.
2. Check for any obstruction inside the damper.
If the electric ventilation damper fails to operate after performing
these checks, it must be replaced.
FOR HVAC INSTALLER AND HOMEOWNER
10
Ultra-Aire 100V Installer’s & Owner’s Manual
ULTRA-AIRE 100V ELECTRICAL SCHEMATIC
