Carrier 48/50AJ specifications W2 G, 124, Board SW1 SW2 SW3 SW4 ECB1 ECB2 SCB CEM

BOARD ADDRESSES — Each board in the system has an address. The MBB has a default address of 1 but it does have an instance jumper that should be set to 1 as shown in Fig. 26. For the other boards in the system there is a 4-dip switch head- er on each board that should be set as shown below.

BOARD	SW1	SW2	SW3	SW4
ECB1	0	0	0	0
ECB2	1	0	0	0
SCB	0	0	0	0
CEM	0	0	0	0

0 = On; 1 = Off

FIELD CONNECTION TERMINAL STRIPS — Field con- nection terminal strips are located in the main control box. See Fig. 32 and Table 122.

Accessory Control Components — In addition to the factory-installed options, the units can also be equipped with several field-installed accessories that expand the control features of the unit. The following hardware components can be used as accessories.

ROOM THERMOSTATS (48/50AJ,AW,A2,A4 UNITS ONLY) — The ComfortLink™ controls support a conven- tional electro-mechanical or electronic thermostat that uses the Y1, Y2, W1, W2, and G signals. The control also supports an additional input for an occupied/unoccupied command that is available on some new thermostats. The ComfortLink controls can be configured to run with multiple stages of capacity which allows up to 6 stages of capacity. Although the unit can be con- figured for normal 2-stage control, it is recommended that the multi-stage control be used. The room thermostat is connected to TB4.

SPACE SENSOR — The ComfortLink controls support the use of space temperature sensors. The T55 and T56 sensors and CCN communicating T58 room sensor can be used. The T55 and T56 sensors are connected to TB5 terminal 3, 4, and 5. The T58 sensor is connected to the CCN connections on TB3. When a T55, T56, or T58 sensor is used, the user must install the red jumpers from R to W1, and W2 on TB4 for the heat function to work correctly.

SPACE CO2 SENSORS — The ComfortLink controls also support a CO2 IAQ sensor that can be located in the space for use in demand ventilation. The sensor must be a 4 to 20 mA sensor and should be connected to TB5 terminal 6 and 7. See Fig. 33 for sensor wiring.

ECONOMIZER HUMIDITY CHANGEOVER SEN- SORS — The ComfortLink controls support 5 different changeover schemes for the economizer. These are:

•outdoor air dry bulb

•differential dry bulb

•outdoor air enthalpy curves

•differential enthalpy

•custom curves (a combination of an enthalpy/dewpoint curve and a dry bulb curve).

The units are equipped as standard with an outside air and return air dry bulb sensor which supports the dry bulb change- over methods. If the other methods are to be used, then a field- installed humidity sensor must be installed for outdoor air en- thalpy and customer curve control and two humidity sensors must be installed for differential enthalpy. Installation holes are pre-drilled and wire harnesses are installed in every unit for connection of the humidity sensors. The ComfortLink controls convert the measured humidity into enthalpy, dewpoint, and the humidity changeover curves.

MOTORMASTER® V CONTROL — For operation below 32 F when an economizer is not used, the units can be equipped with an accessory Motormaster V control, which controls the speed of the stage 1 condenser fans. The Motormaster V control is a 3-phase inverter that controls the speed of the fans based on a pressure transducer connected to the liquid line. On 48/ 50A020-035 units, one fan will be controlled. On 48/50A036- 060 units, two fans will be controlled. For units equipped with an economizer, there should not be a need for this control be- cause the economizer can provide free cooling using outside air, which will be significantly lower in operating cost.

The accessory Motormaster V speed control is a completely self-contained control and is not controlled by the unit’s ComfortLink controller. On 48/50A051 and 060 units with 6 fan motors, the Motormaster control configuration (M.M.) must be set to YES. See page 39.

ACCESSORY NAVIGATOR™ DISPLAY — The accesso- ry handheld Navigator display can be used with the 48/50A se- ries units. See Fig. 34. The Navigator display operates the same way as the scrolling marquee device. The ECB1 and ECB2 boards contain a second LEN port (J3 connection) than can be used with the handheld Navigator display.

CONTROL MODULE COMMUNICATIONS

Red LED — Proper operation of the control boards can be visually checked by looking at the red status LEDs as shown on Fig. 26-29. When operating correctly, the red status LEDs should blink in unison at a rate of once every 2 seconds. If the red LEDs are not blinking in unison, verify that correct power is being supplied to all modules. Also, be sure that the main base board is supplied with the current software. If necessary, reload current software. If the problem still persists, replace the MBB. A board LED that is lit continuously or blinking at a rate of once per second or faster indicates that the board should be replaced.

TB3						+	C	-	GRD		1	3	5	7	9	11	13	15
			LEN	CCN			CCN
TB4		R	Y1	Y2	W1	W2 G		C	X		2	4	6	8	10	12	14	16
	1		2	3	4	5	6	7	8
										1		3	5	7	9	11	13	15

A48-7081 2 4 6 8 10 12 14 16

Fig. 32 — Field Connection Terminal Strips (Main Control Box)

TB5

TB6

124