Lennox MERIT ML195UH Installation Instructions Manual page 39

• The furnace integrated control requires both po-
larity and proper ground. Both polarity and proper
grounding should be checked before attempting to
operate the furnace on either permanent or tempo-
rary power.
• Generator should have a wave form distortion of
less than 5% THD (total harmonic distortion).
Thermostat
Install the room thermostat according to the instructions
provided with the thermostat. See figure 59 for thermostat
designations. If the furnace is being matched with a heat
pump, refer to the FM21 installation instruction or appro-
priate dual fuel thermostat instructions.
Indoor Blower Speeds
1 - When the thermostat is set to "FAN ON," the indoor
blower will run continuously on the heating speed
when there is no cooling or heating demand.
2 - When the ML195UH is running in the heating mode,
the indoor blower will run on the heating speed.
3 - When there is a cooling demand, the indoor blower
will run on the cooling speed.
Note - This control is equipped with a push button switch
for diagnostic code recall. The control stores the last 5
fault codes in non-volatile memory.
LED
PUSH BUTTON
TWIN
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
BLOWER OFF
DELAY JUMPER
The most recent fault code is flashed first, the oldest fault
code is flashed last. There is a 2 second pause between
codes. When the push button switch is pressed for less
than 5 seconds, the control will flash the stored fault codes
when the switch is released. The fault code history may be
cleared by pressing the push button switch for more than
5 seconds.
LED Status
LED Off
LED On
1 Flash
2 Flashes
3 Flashes
4 Flashes
5 Flashes
6 Flashes
7 Flashes
8 Flashes
9 Flashes
TERMINAL DESIGNATIONS
Humidifier (120VAC)
HUM
Input (120VAC)
LINE
Transformer (120VAC)
XFMR
Indoor Air Qality Accessory Air Cleaner (120VAC)
EAC
Blower - Cooling Speed (120VAC)
COOL
Blower - Heating Speed (120VAC)
HEAT
Dead terminals to park alternate spd taps
PARK
Continuous blower
CONT
Neutral terminals (120VAC)
NEUTRALS
Twinning Terminal (24VAC)
TWIN
FIGURE 58
Page 39
DIAGNOSTIC CODES
Description
No power to control or control
harware fault detected.
Normal operation.
Flame present with gas vavle
de-energized.
Pressure switch closed with com-
bustion air inducer e-energized.
Pressure switch open with com-
bustion air inducer energized.
Primary limit switch open.
Rollout switch open.
Pressure switch cycle lockout.
Lockout, burners fail to light.
Lockout, buners lost flame too
many times.
Line voltage polarity incorrect.