Major System Components; General; Main Base Board (Mbb); Economizer Control Board (Ecb) - Carrier 48PG03-16 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

Table 101—Pressure (psig) vs. Voltage Drop Values for Suction Pressure Transducers
PRESSURE VOLTAGE
(psig) DROP (V)
0
0.465
2
0.485
4
0.505
6
0.524
8
0.544
10
0.564
12
0.583
14
0.603
16
0.623
18
0.642
20
0.662
22
0.682
24
0.702
26
0.721
28
0.741
30
0.761
32
0.780
34
0.800
36
0.820
38
0.839
40
0.859
42
0.879
44
0.898
46
0.918
48
0.938
50
0.958
52
0.977
54
0.997
56
1.017
58
1.036
60
1.056
62
1.076
64
1.095
66
1.115

MAJOR SYSTEM COMPONENTS

General

The 48/50PG single package rooftop units contain the
ComfortLink™ electronic control system that monitors all
operations of the rooftop. The control system is composed of
several main control components and available factory-
installed options or field-installed accessories as listed in
sections below. See Fig. 22-24 for the control and power
schematics. See Fig. 25-27 for units with Humidi-MiZer™
system. Fig. 28 shows the layout of the control box, unit, and
thermistor and transducer locations.

Main Base Board (MBB)

See Fig. 29 and Table 102. The MBB is the center of the
ComfortLink control system. It contains the major portion of the
operating software and controls the operation of the unit. The
MBB continuously monitors input/output channel information
received from its inputs and from the Economizer Control Board
(ECB). The MBB receives inputs from thermistors and
transducers. The MBB also receives the Current Sensor inputs for
compressors and other discrete or digital inputs. The MBB reads
space temperature (SPT) from either a T-55, T-56 or T-58 device
and space temperature offset (SPTO) from a T-56 device. See
Field-Installed Accessories section. The MBB controls 9 relays.
NOTE: The Main Base Board (MBB) has a 3-position instance
jumper that is factory set to '1.' Do not change this setting.

Economizer Control Board (ECB)

The ECB controls the economizer actuator. (See Fig. 30 and
Table 103.) The control signal from the ECB uses either the
MFT (Multi-Function Technology) digital communication
PRESSURE VOLTAGE
(psig) DROP (V)
68
1.135
70
1.154
72
1.174
74
1.194
76
1.214
78
1.233
80
1.253
82
1.273
84
1.292
86
1.312
88
1.332
90
1.351
92
1.371
94
1.391
96
1.410
98
1.430
100
1.450
102
1.470
104
1.489
106
1.509
108
1.529
110
1.548
112
1.568
114
1.588
116
1.607
118
1.627
120
1.647
122
1.666
124
1.686
126
1.706
128
1.726
130
1.745
132
1.765
134
1.785
PRESSURE VOLTAGE
(psig) DROP (V)
136
1.804
138
1.824
140
1.844
142
1.863
144
1.883
146
1.903
148
1.922
150
1.942
152
1.962
154
1.982
156
2.001
158
2.021
160
2.041
162
2.060
164
2.080
166
2.100
168
2.119
170
2.139
172
2.159
174
2.178
176
2.198
178
2.218
180
2.237
182
2.257
184
2.277
186
2.297
188
2.316
190
2.336
192
2.356
194
2.375
196
2.395
198
2.415
200
2.434
202
2.454
protocol or a 4 to 20 mA output signal as defined by the
configuration Configuration→ECON→E.CTL. The ECB has
inputs for Indoor Air Quality (IAQ), Outdoor Air Quality
(OAQ), and enthalpy. It also controls two power exhaust
outputs.
By digitally communicating with the ECB, the economizer
actuator is able to provide the damper position and diagnostic
information to the ComfortLink controller. The damper
position is displayed at Outputs→ECON→EC.AP. Diagnostic
information is displayed via Alert T414. More information about
these alarms is contained in the Alarms and Alerts section.
NOTE:
The Economizer Control Board (ECB) has a
4-position DIP switch that is factory set to '0'. Do not change
this setting.

Integrated Gas Control (IGC) Board

The IGC is provided on gas heat units. See Fig. 31 and Table
104. The IGC controls the direct spark ignition system and
monitors the rollout switch, limit switch, and induced-draft motor
Hall Effect switch. The IGC is equipped with an LED (light-
emitting diode) for diagnostics. See the Troubleshooting
section for more information.

Low Voltage Terminal Strip (TB1)

This circuit board provides a connection point between the major
control boards and a majority of the field-installed accessories.
See Fig. 32 and Table 105. The circuit breakers for the low
voltage control transformers, interface connection for the Carrier
Comfort Network® (CCN) communication, and interface
connection for the Local
communications are also located on the low voltage terminal
strip.
94
PRESSURE VOLTAGE
(psig) DROP (V)
204
2.474
206
2.493
208
2.513
210
2.533
212
2.553
214
2.572
216
2.592
218
2.612
220
2.631
222
2.651
224
2.671
226
2.690
228
2.710
230
2.730
232
2.749
234
2.769
236
2.789
238
2.809
240
2.828
242
2.848
244
2.868
246
2.887
248
2.907
250
2.927
252
2.946
254
2.966
256
2.986
258
3.005
260
3.025
262
3.045
264
3.065
266
3.084
268
3.104
270
3.124
Equipment Network (LEN)