COMFORT-AIRE Century GUH96T045B3M, Service Manual

Page: 7 / 52

508183-01 Issue 2114 Page 7 of 52
CFM LED
An amber LED is provided on the control board to display
CFM. To determine what CFM the motor is delivering
at any time, count the number of times the amber LED
flashes. Each flash signifies 100 CFM; count the flashes
and multiply by 100 to determine the actual CFM delivered
(for example: 5 flashes x 100 = 500 CFM).
LED Status Description
LED Off No demand for high heat
LED On HIgh heat demand, operating normally
LED Flashing
High heat demand, high pressure
switch not closed
Table 1. High Heat State Green LED
LED Status Description
LED Off
No power to control or control hardware
fault detected
LED On Normal operation
1 Flash Flame present with gas valve de-energized
2 Flashes
Pressure switch closed with combustion air
inducer de-energized
3 Flashes
Low-fire pressure, rollout or limit switch
open
4 Flashes Primary limit switch open
5 Flashes Not used
6 Flashes Pressure switch cycle lockout
7 Flashes Lockout, burners fail to light
8 Flashes Lockout, burners lost flame too many times
9 Flashes Line voltage polarity incorrect
Table 2. Diagnostic Codes Red LED
Pin # Function
1 Ignitor (Hot)
2 Combustion Air Inducer High Speed
3 Combustion Air Inducer Low Speed
4 Combustion Air Inducer Neutral
5 Ignitor Neutral
Table 3. Control 5-Pin Terminal Designation
Airflow Adjustments
Cooling Mode
The units are factory set for the highest airflow for each
model. Adjustments can be made to the cooling airflow
by repositioning the jumper plug marked COOL – A, B,
C, D (see Figure 3). To determine what CFM the motor is
delivering at any time, count the number of times the amber
LED on the control board flashes. Each flash signifies 100
CFM; count the flashes and multiply by 100 to determine
the actual CFM delivered (for example: 5 flashes x 100 =
500 CFM).
Pin # Function
1 Gas Valve Second Stage
2 Second Stage Prove Switch
3 Rollout Switch In
4 Ground
5 24V Hot
6 Primary Limit In
7 Gas Valve First Stage
8 Gas Valve Common
9 24V Neutral
10 Ground
11 Rollout Switch Out
12 First Stage Prove Switch
Table 4. 12-Pin Terminal Designation
Heating Mode
These units are factory set to run at the middle of the
heating rise range as shown on the unit rating plate. If
higher or lower rise is desired, reposition the jumper plug
marked HEAT - A, B, C, C (see Figure 3). To determine
what CFM the motor is delivering at any time, count the
number of times the amber LED on the control board
flashes. Each flash signifies 100 CFM; count the flashes
and multiply by 100 to determine the actual CFM delivered
(for example: 5 flashes x 100= 500.
Adjust Tap
Airflow amounts may be increased or decreased by 10%
by moving the ADJUST jumper plug (see Figure 3) from
the NORM position to the (+) or (-) position. Changes to the
ADJUST tap will affect both cooling and heating airflows.
The TEST position on the ADJUST tap is not used.
Continuous Blower Operation
The comfort level of the living space can be enhanced
when using this feature by allowing continuous circulation
of air between calls for cooling or heating. The circulation
of air occurs at half the full cooling airflow rate.
To engage the continuous blower operation, place the
fan switch on the thermostat into the ON position. A call
for fan from the thermostat closes R to G on the ignition
control board. The control waits for a 1 second thermostat
delay before responding to the call for fan by ramping
the circulating blower up to 50% of the cooling speed.
When the call for continuous fan is satisfied, the control
immediately ramps down the circulating blower.