![background image](http://html.mh-extra.com/html/carrier/weathermaker-50tcq-17-24-series/weathermaker-50tcq-17-24-series_service-and-maintenance-instructions_2560326022.webp)
22
Jumper for 1-3 seconds: Factory Test, defrost runs for 9 seconds.
Jumper for 5-20 seconds: Forced Defrost, defrost runs for 30 seconds if DFT2 is open.
Reversing Valve Control
The DFB has two outputs for unit reversing valve control. Opera
-
tion of the reversing valves is based on internal logic; this applica
-
tion does not use an “O” or “B” signal to determine reversing
valve position. Reversing valves are energized during the cooling
stages and de-energized during heating cycles. Once energized at
the start of a cooling stage, the reversing valve will remain ener
-
gized until the next heating cycle demand is received. Once de-en
-
ergized at the start of a Heating cycle, the reversing valves will re
-
main de-energized until the next cooling stage is initiated.
Compressor Control
The DFB receives inputs indicating Stage 1 Cooling, Stage 2
Cooling (sizes 08 and 09 only) and Stage 1 Heating from the space
thermostat or unit control system (PremierLink
™
or RTU-OPEN);
it generates commands to start compressors with or without re
-
versing valve operation to produce Stage 1 Cooling (one compres
-
sor), Stage 2 Cooling (both compressors run) or Stage 1 Heating
(both compressors run).
Auxiliary (Electric) Heat Control
The 50TCQ unit can be equipped with one or two auxiliary elec
-
tric heaters, to provide a second stage of Heating. The DFB will
energize this Heating system for a Stage 2 Heating command
(heaters operate concurrently with both compressors in the Stage 1
Heating cycle), for an Emergency Heating sequence (compressors
are off and only the electric heaters are energized) and also during
the Defrost cycle (to eliminate a “cold blow” condition in the
space).
Defrost
The defrost control mode is a time/temperature sequence. There
are two time components: The continuous run period and the test/
defrost cycle period. The temperature component is provided by
the defrost thermostat(s) (DFT1 and DFT2) mounted on the out
-
door coil.
The continuous run period is a fixed time period between the end
of the last defrost cycle (or start of the current Heating cycle)
during which no defrost will be permitted. This period can be set
at 30, 60, 90 or 120 minutes by changing the positions of DIP
switches SW1 and SW2 (see Fig. 32 and Table 9).
Fig. 32 — DIP Switch Settings — Defrost Board
Table 8 —
50TCQ Defrost Board I/O and Jumper Configurations
INPUTS
POINT NAME
TYPE OF I/O
CONNECTION PIN NUMBER
UNIT CONNECTION
NOTE
G Fan
DI, 24Vac
P2–3
LCTB–G
Y1 Cool 1
DI, 24Vac
P2–5
LCTB–Y1
Y2 Cool 2
DI, 24Vac
P2–4
LCTB–Y2
W1 Heat 1
DI, 24Vac
P2–7
LCTB–W1
W2 Heat 2
DI, 24Vac
P2–6
LCTB–W2
R Power
24Vac
P3–1
CONTL BRD–8
C Common
24Vac
P3–2
CONTL BRD–4
DFT1
DI, 24Vac
DFT–1 to DFT–1
DFT 2
DI, 24Vac
DFT–2 to DFT–2
OUTPUTS
POINT NAME
TYPE OF I/O
CONNECTION PIN NUMBER
UNIT CONNECTION
NOTE
IFO Fan On
DO, 24Vac
P3–9
REHEAT–2
OF OD Fan On
DO, 24Vac
OF
OFR
RVS1
DO, 24Vac
P3–7 to P3–5
Energize in COOL
RVS2
DO, 24Vac
P3–6 to P3–4
Energize in COOL
COMP 1
DO, 24Vac
P3–10
FPT –REHEAT–6
COMP 2
DO, 24Vac
P3–8
REHEAT–8
HEAT 2
DO, 24Vac
E–HEAT
HC–1 (TB4–1)
COM
24Vac
P3–3
HC–1 (TB4–3)
CONFIGURATION
POINT NAME
TYPE OF I/O
CONNECTION PIN NUMBER
UNIT CONNECTION
NOTE
Select Jumper
24Vac
P1–1
2 Compressor
24Vac
P1–3
Use for 50TCQD
SPEED-UP CONFIGURATION
POINT NAME
TYPE OF I/O
CONNECTION PIN NUMBER
UNIT CONNECTION
NOTE
Speed–Up Jumper
JMP17
Speed–Up Jumper
JMP18
Summary of Contents for WeatherMaker 50TCQ 17-24 Series
Page 35: ...35 Fig 53 RTU Open Overlay for Economizer Wiring ...
Page 36: ...36 Fig 54 VFD Overlay for W2770 Controller Wiring ...
Page 68: ...68 Fig B 50TCQD17 24 Control Wiring Diagram APPENDIX D WIRING DIAGRAMS ...
Page 69: ...69 Fig C 50TCQD17 24 Power Wiring Diagram 208 230 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 70: ...70 Fig D 50TCQD17 24 Power Wiring Diagram 460 3 60 575 3 60 Units APPENDIX D WIRING DIAGRAMS ...
Page 71: ...71 Fig E RTU Open Overlay APPENDIX D WIRING DIAGRAMS ...
Page 72: ...72 Fig F PremierLink Overlay APPENDIX D WIRING DIAGRAMS ...