High Or Primary Limit - Amana 10759833 Installation Instructions Manual

High or Primary Limit

The primary limit control guards against overheating re-
sulting from insufficient conditioned air passing over the
heat exchanger. If the primary limit control does not
function during this test, the cause must be determined and
corrected. Function of this control should be verified by
gradually blocking the furnace return air after the furnace
has been operating (burners firing) for approximately 15
minutes. Check the control as follows:
1. Allow the furnace to operate with burners firing con-
tinuously for approximately 15 minutes.
2. Gradually block the return air to furnace. Remove
airflow blockage when limit control is activated and
turns off burners. Airflow blockage causes unit over-
heating and will produce the following reactions:
• The gas valve to close and extinguish flame,
• The induced draft blower to deenergized after a
fifteen second postpurge, and
• The circulator blower to remain energized continu-
ously until limit control resets.
Indoor Fan
Outdoor Fan
And
Compressor
Thermostat
Operational Checks
On
Off
On
Off
On
Off
Seconds 0 5
37 37
3. Remove the return air blockage to clear overheating
condition. After an acceptable temperature is
reached during the cool down period, the limit control
will reset and allow the furnace to resume normal op-
eration.
These checks establish that the primary limit control is
functioning and will respond to a restriction in the return air,
or a circulator blower failure. If the primary limit control
does not function during this test, the cause must be
determined and corrected.
Primary Limit Control
0
Primary Limit Control
45