Lennox MPGA 050 B3, Application Manual

11. Set the thermostat to the desired setting.

12. If the furnace will not operate, follow the instructions

in 

"To Turn Off Gas to Furnace"

 and call your

service technician or gas supplier.

To Turn Off Gas to Furnace

 1. Set the thermostat to the lowest setting.

 2. Turn off all electric power to the furnace if service is

to be performed.

 3. Remove the burner compartment access panel.

 4. Move the gas control switch to "OFF" (see Figure 1).

Do not force.

 5. Replace the burner compartment access panel.

Temperature Control

There are many types and styles of thermostats. Yours
may look different from the one pictured in Figure 2,
depending on the type of thermostat and whether cooling
was installed with the system. However, almost all
thermostats perform the same basic functions described
in the following section.

Figure 2

Thermostat Operation

There are two (2) switches located on the thermostat (see
Figure 2). One switch controls the heating and cooling (if
applicable) functions. The other switch is for "FAN"
operation, either continuous or automatic. On the
thermostat is the temperature range for the heating
temperature and the cooling temperature desired.

To put the system into operation, push the switch to
either "HEAT" or "COOL" position. After you have chosen
the type of operation you desire, move the thermostat dial
or lever to select the temperature you would like the
system to maintain.

Fan Operation

You may wish to increase your comfort by setting your
system for continuous air circulation of the indoor air.
The fan switch on the thermostat permits you to do this.

With the switch in the "ON" position the fan will operate
continuously. "AUTO" position gives fan operation only
when the unit is in either heating or cooling.

What to do if your unit is not heating properly

If your furnace is operating but fails to provide complete
comfort, check the following before calling for service:

 1. Be sure the thermostat setting is correct.

 2. Check to see if the filter is clean.

 3. Be sure air can circulate freely throughout your home.

Do not block supply registers or return grilles with
furniture or rugs.

And if you also have cooling...

 4. Keep surface of the outdoor coil free from dirt, lint,

paper, or leaves.

 5. Check and clean indoor coil, if necessary. (This

check should be made at the start of each cooling
season by your service technician).

What to do if your unit fails to operate

 1. Be sure the main switch that supplies power to the

furnace is in the "ON" position.

 2. Replace any burned-out fuses or reset circuit

breakers.

 3. Be sure the thermostat is properly set.

 4. If the furnace still does not start, call your service

technician.

Should the gas supply fail to shut off or if
overheating occurs, shut off the gas valve to the
furnace before shutting off the electrical supply.

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