Carrier 50FK - Manual (Page 3)

Several temperature inputs are connected to the proces-
sor. There are either 4 or 5 thermistors (depending on the
field-installed accessories) which input temperature data
into the processor through pin terminal connector J1. See
Table 1 and Fig. 2.
Several status switches are also monitored. These switches
are connected to the processor at pin terminal connector J2.
See Fig. 3 and Table 2.
Table 1 — Pin Terminal Connector J1
Thermistor Inputs
CONNECTOR J1
TERMINAL NO.
TEMPERATURE
INPUT
UNIT SIZE
034-104
1,2 Reset Temperature* T10
14,15
Saturated Condensing
Temp., Circuit 2
T4
16,17
Saturated Condensing
Temp., Circuit 1
T3
18,19 Return-Air Temperature T2
20,21 Supply-Air Temperature T1
LEGEND
T — Thermistor
*If equipped with accessory temperature reset package.
NOTE: Terminal numbers 3-13 are not used on these units.
In addition to the unit status switch inputs, the processor
board also accepts inputs from several potentiometers. These
potentiometers control various operational characteristics of
the system. Inputs are received by the processor through pin
terminal connector J3. See Fig. 4.
All of the potentiometers must be set before the unit is
started in order for the unit to function properly. See Start-
Up, Potentiometers section on page 28 for information on
establishing set points. Each of the potentiometers has a valid
range that is used by the control. The valid range is defined
as the potentiometer’s resistance value that the control will
not consider to be in error. This is usually between 10% and
90% of the potentiometer’s total resistance. The control has
been programmed to accept an operational range for the po-
tentiometer, which may not be the same as the valid range.
LEGEND
DIP — Dual In-Line Package
EPROM — Erasable, Programmable Read-Only Memory
EXV
— Electronic Expansion Valve
Do not remove label covering EPROM. Removal causes pro-
gram to be erased.
Fig. 1 — Processor Board
*EPROM HT204485-1-XX where ‘‘XX’’ is the current revision
number.
NOTE: Processor Board is positioned in unit with J3 and J10 con-
nections at the bottom.
3