Carrier 50EJQ Installation, Start-Up And Service Instructions Manual page 35

CHECK VALVES
COOLING HEATING
A Closed Open
B Open Closed
C Closed Open
D Open Closed
E Closed Open
F Open Closed
Diagnostic LEDs (Light-Emitting Diodes) —
are 3 LEDs (red, yellow, and green) on the lower left hand
side of the control board. The red light is used to check
unit operation and alarms. A constant pulse is normal unit
operation. A series of quick blinks indicates an alarm. Refer
to Table 17 on next page for a description of alarms. The
NOTES:
1. Hot gas from compressor flows through the 4-way valve and is directed to the
outdoor coil header. At the header it is condensed and subcooled through converging
circuits (10-3-2). Refrigerant leaves the outdoor coil by way of the check valve to the
liquid line.
2. The refrigerant then flows through the filter drier and feeds the indoor coil by way of
fixed orifice tubes on each circuit.
3. Each circuit evaporates the refrigerant, and the circuits are combined in the indoor coil
header with some of the circuits flowing through the check valve.
4. The refrigerant then flows through the 4-way valve, accumulator and back to the
compressor.
Fig. 44 — Typical Refrigerant Circuiting (Cooling)
There
yellow LED blinks during transmission with the CCN
(Carrier Comfort Network). The green LED blinks during
transmission with the expansion board.
Channel Designations —
input and output channel designations.
35
Tables 18 and 19 show the