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All installations and services must be performed by qualified service personnel.
Motor Blower Speed
Three interconnected blower speed outputs are provided. A "G" call for fan will provide
power to the LOW speed tap only. A "W" heat call will provide power to the Heat speed tap
only. A "Y" cooling call will provide power to the Cool speed tap only.
In the case of thermostat calls for "Y" and "W" together, blower speed selection will be
determined by the input that was first initiated. In the case where the control is in a cooling mode
with both "Y" and "W" inputs energized and then the "Y" input is removed, the cooling blower
off time will be executed prior to the control switching into a heating mode. In the case where
the control is in a heating mode with both "Y" and "W" inputs energized and then the "W" input
is removed, the heating blower off time will be executed prior to the control switching into a
cooling mode. In the case where a call for fan "G" already exists and either a "W" or a "Y" call
is initiated, the blower speed will switch to the respective "W" or a "Y" speed following the
blower on delay for that call.
The speed taps are interconnected and interlocked, only one speed may be powered at any one
time. When a speed is to be operated, the speed select relays are operated to select the path to the
motor tap and then the enable relay is operated to switch the operating power to the selected
motor speed tap. If the speed of the running motor is to be changed, first the enable relay
removes power from the motor, the new speed is selected and then power is restored to the
motor.
Blower On and Off Delays
Four Heat blower on and four blower off delays are selected by two dip switches for each
function. Refer to Table 8 for specific delay values.
Trouble Shooting - Diagnostic Features
for UT board
The control board is equipped with 4 green Input Status LEDs and 1 red Board Status LED.
These are intended to provide a quick view into furnace performance without requiring a
voltmeter.
The green Input Status LEDs are driven by the "Y", "W", "G", and "DEHUM" inputs and are
located directly below those inputs. They will light to indicate the presence of these signals.
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