Carrier JK034-074, 50FK, 48FK Pin Terminal Connector J1 Thermistor Inputs, Dip, Exv, 20,21

		LEGEND
DIP	Ð	Dual In-Line Package
EPROM Ð Erasable, Programmable Read-Only Memory
EXV	Ð	Electronic Expansion Valve

Do not remove label covering EPROM. Removal causes pro- gram to be erased.

*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.

Fig. 1 Ð Processor Board

Several temperature inputs are connected to the proces- sor. There are either 4 or 5 thermistors (depending on the ®eld-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 Ð Pin Terminal Connector J1

Thermistor Inputs

CONNECTOR J1	TEMPERATURE	UNIT SIZE
TERMINAL NO.	INPUT	034-104
1,2	Reset Temperature*	T10
14,15	Saturated Condensing	T4
	Temp., Circuit 2
16,17	Saturated Condensing	T3
	Temp., Circuit 1
18,19	Return-Air Temperature	T2
20,21	Supply-Air Temperature	T1

LEGEND

T Ð 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 de®ned 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.

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