Rheem 97MDV060 Series Installation Instructions Manual page 80

INTEGRATED FURNACE CONTROL
SUPPLY AND OUTDOOR AIR TEMPERATURE SENSORS
16. SUPPLY AND OUTDOOR AIR TEMPERATURE
SENSOR INPUTS (T4) see Figure 54
Optional field-installed supply air and outdoor air sensors
(10K NTC thermistor) shall be read from the T4 screw
terminal block.
Control to resolve temperature within +/-2°F at 70°F There
is to be an automatic detection of the supply and outdoor
air sensors. If the resistance between the terminals is
within a valid 10K thermistor range (supply air temp range
= -40°F to 200°F, outdoor air temp range = -40 to 200°F),
both sensors temperatures will be accessible.
If the resistance between the supply air terminals is
determined to be out of range to a high resistance, it shall
be interpreted as an uninstalled supplied air sensor and
shall not cause an error condition unless a valid thermistor
value was previously sensed on the same power cycle. If
the sensor was determined to be present and then is
opened the control should display a fault "82". The fault is
a level 1 fault and will not inhibit furnace operation. Also, if
the resistance between the terminals is determined to be
out of range to a low resistance and a valid thermistor
value was sensed on the same power cycle, a fault "82" is
to be displayed on the seven segment displays.
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If the resistance between the outdoor air terminals (OAT)
is determined to be out of range to a high resistance, it
shall be interpreted as an uninstalled supplied outdoor air
sensor and shall not cause an error condition unless a
valid thermistor value was previously sensed on the same
power cycle. If the sensor was determined to be present
and then is opened, the control should display a fault
"84". The fault is a level 1 fault and will not inhibit furnace
operation.
Also, if the resistance between the terminals on the OAT is
determined to be out of range to a low resistance, a fault
"84" is to be displayed on the seven segment displays
only if a valid thermistor value was previously sensed on
the same power cycle.
Fault codes "82" and "84" shall only be present for three
minutes after the fault is detected. After three minutes has
expired, the fault will no longer be set even if the condition
creating the fault is still present. These faults are also only
logged into the fault buffer one time. Should the sensor
error later clear and then appear again the same
sequence as noted previously will be repeated.