Lennox ML296UHV Series - Page 10

Page 10
TABLE 2
Diagnostic Codes Red LED
LED Status Description
LED O󰀨
No power to control or control har-
ware fault detected.
LED On Normal operation.
1 Flash
Flame present with gas vavle de-en-
ergized.
2 Flashes
Pressure switch closed with combus-
tion air inducer de-energized.
3 Flashes
Low-re 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, buners lost ame too many
times.
9 Flashes Line voltage polarity incorrect.
TABLE 3
Control 5 Pin Terminal Designation
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
Airow Adjustments
Cooling Mode
The units are factory set for the highest airow for each
model. Adjustments can be made to the cooling airow by
repositioning the jumper plug marked COOL – A, B, C, D
(see FIGURE 3). To determine what CFM the motor is de-
livering at any time, count the number of times the amber
LED on the control board ashes. Each ash signies 100
CFM; count the ashes and multiply by 100 to determine
the actual CFM delivered (for example: 5 ashes x 100 =
500 CFM).
Fan on / o󰀨 delay
On a call for heat there is a 30 second fan on delay after
igntion.When the call for heat is satised, the gas valve
and combustion air blower shut down. The circulating air
blower continues to run for selected blower o󰀨 delay time
(60/90/120/180 sec) before ramping down and shutting
o󰀨. The fan on delay is 30 seconds and not adjustabe.
NOTE - The fan o delay on ML296-55 and earlier units is
factory set at 120 seconds and NON- ADJUSTABLE.
TABLE 4
12 Pin Terminal Designation
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
Heating Mode
These units are factory set to run at the middle of the heat-
ing 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, 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 ashes. Each
ash signies 100 CFM; count the ashes and multiply by
100 to determine the actual CFM delivered (for example:
5 ashes x 100= 500.
Adjust Tap
Airow 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 a󰀨ect both cooling and heating air-
ows. 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 airow 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 circu-
lating blower up to 50% of the cooling speed. When the
call for continuous fan is satised, the control immediately
ramps down the circulating blower.