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IM 938-4 / Page 19 of 42
The Display will show the upper operating limits first. The
default settings are Cool min. = 60°F and Heat max. = 85°F.
4) Fresh Air Damper Control
To advance from Heat Maximum Set point, to Fresh Air
Damper Control operation, press the Mode button once.
Using the Up and Down buttons, toggle between "AU"
for Automatic and "CL" for (forced) Closed.
The Fresh Air Damper will operate when the following
conditions are met:
A. Damper setting in the touchpad set-up mode is “AU”
(automatic) AND
B. Indoor fan motor turns on AND
C. Outdoor Air Sensor (OAS) temperature is greater than
40ºF but less than 90ºF AND
D. Indoor Air Sensor (IAS) temperature greater than 50ºF.
This control can be overridden by changing the damper set
-
ting in the set-up mode to “CL” (Close).
Optional Indoor Air Quality Boost Fan
The IAQ Boost Fan will operate in conjunction with the
Fresh Air Damper
and increase the volume of fresh air to
90 CFM. The Fresh Air Damper and Boost Fan will operate
when the following conditions are met:
A. Damper setting in the touchpad set-up mode is “AU”
(automatic) AND
B. Indoor fan motor turns on AND
C. Outdoor Air Sensor (OAS) temperature is greater than
40°F but less than 90°F AND
D. Indoor Air Sensor (IAS) temperature greater than 50°F.
This control can be overridden by closing the damper and
turning off the Boost Fan, by changing the damper setting in
the Set-up Mode to “CL” (Close).
5) Heat Pump By-Pass
to advance to Heat Pump By-Pass setting for both Basic
and Premium boards, when HP/E is selected in "Control
Select", use the Up and Down buttons to toggle between
"Au" for Automatic or "bY" for Bypass for Heat Pump
operation. Default setting is "Au"
6) Electric Heat By-Pass
To advance from Heat Pump to Electric Heat By-Pass,
press the Mode button once. This screen will only appear
when HP/E selection is "Au" and the outdoor coil sensor
is at or above 40°F. Using the Up and Down buttons,
toggle between "Au" for Automatic or "bY" for Bypass
setting. In "bY" setting, electric heat is the only source
of heat.
7) Indoor Air Sensor Reading
To advance from Fresh Air Damper Control, Heat pump
or Electric Heat operation to Indoor Air Sensor Reading,
press the Mode Button once. The display will show
return air temperature.
8) Indoor Coil Sensor Reading
To advance from Indoor Air Sensor Reading to Indoor
Coil Sensor Reading, press the Mode Button once. The
display will show the indoor coil sensor temperature.
Figure 30: Indoor Air and Indoor Coil Sensor Locations
Indoor Coil
Sensor (ICS)
Indoor Air
Sensor (IAS)
9) Outdoor Air Sensor Reading
To advance from Indoor Coil Sensor Reading to Outdoor Air
Sensor Reading, press the Mode Button once. The display
will show the Outdoor Air Sensor temperature.
10) Outdoor Coil Temperature Reading
To advance from Outdoor Air Sensor Reading to Outdoor
Coil Temperature Reading, press the Mode Button once. The
display will show the Outdoor Coil termperature.
Figure 31: Outdoor Air Sensor Location
Outdoor Air Sensor
(OAS)
Thermistor Error Codes and
Conditions
Refer to
"Fault and Protection Codes for Applied PTAC/
PTHP Control Board" on page 36.
The system treats a sensor open or short as extremely cold
or hot and reacts accordingly. The exception is the room air
sensor, in which case the system will turn off. When the fault
is corrected by replacement or repair, the respective error
code will clear from the display (See
Table 2
).
Table 2: Failure Code and Condition
Thermistor Sensor
Condition
Error Code
< - 58°F or
Room
> 140°F or
E1
Open or Close
< - 50°F for > 2s or
Indoor Coil
> 176°F for > 2s or
E2
Open or Close
< - 50°F for > 2s or
Outdoor Air
> 176°F for > 2s or
E4
Open or Close