Symptom: Evaporator fan will not operate.
1. Turn unit power off and disconnect plug P1 from the con-
trol board.
2. Install a jumper across Pin R and Pin G at plug P1 on the
control board.
3. Turn unit power on and check if the indoor (evaporator)
fan contactor (IFC) coil has been pulled in. If the con-
tactor has not been pulled in, check the voltage across the
IFC coil. If there is voltage at this point, the IFC con-
tactor is defective. If there is no voltage, proceed to
Step 4.
4. Turn unit power off and disconnect plug P4 from the con-
trol board.
5. Turn unit power on and check for continuity across
Pin 6 and Pin 3 at plug P4 on the control board. If there
is no continuity, the board is defective. Replace control
board. If there is continuity, then there is a bad con-
nection between the board and plug P4. Correct the
connection.
6. Turn unit power off. Reconnect plug P1 (if troubleshoot-
ing is complete) and plug P4.
Symptom: Condenser fan no. 1 will not operate.
1. Turn unit power off. Disconnect plugs P1 and P3 from
the control board.
2. Check for continuity between Pin 8 at plug P3 on the con-
trol board and Pin Y1 at plug P1 on the control board. If
there is no continuity, the board is defective. If there is
continuity, either the connection is bad between plug P3
and the control board or the problem is external to the
board. Reconnect plug P1 (if troubleshooting is com-
plete) and plug P3 to the board.
Symptom: Condenser fan no. 2-5 will not operate.
1. Check operation of condenser fan no. 1. If fan no. 1 op-
erates properly, the problem is external to the board.
Symptom: Compressor no. 1 will not operate.
1. Turn unit power off. Disconnect the 2 wires attached to
the terminals marked SC1.
2. Check continuity between the 2 wires. If there is no
continuity, the problem is external to the control board
(possibly the pressure switches). If there is continuity, pro-
ceed to Step 3.
3. Reconnect the wires removed in Step 1.
4. With the unit power still off, disconnect plug P1 from con-
trol board. Install a jumper wire across Pin R and Pin Y1
at plug P1 on the control board.
5. Connect a voltmeter across the coil for compressor
no. 1 contactor.
6. Energize unit and monitor the voltage for a few
seconds.
IMPORTANT: Do not run compressor too long.
7. a. If proper voltage is indicated at the contactor, but con-
tactor fails to close, replace contactor.
b. If voltage is indicated for a few seconds (i.e., the con-
tactor momentarily pulls in and is then deenergized),
the compressor lockout (CLO) logic has shut down
the unit. This is an indication that the board is not sens-
ing proper compressor current, or that one of the safe-
ties has tripped. Proceed to Step 8 to verify compres-
sor lockout logic operation.
LEGEND
CLO — Compressor Lockout
P
— Plug
SC
— Safety Circuit
Fig. 64 — Control Board Component Arrangement
54
Summary of Contents for 48DJ
Page 58: ...Fig 66 Gas Heat Sections 48DJ NP034 044 Units 58...
Page 59: ...Fig 67 Gas Heat Sections 48DJ NP054 074 Units 59...
Page 60: ...Fig 68 Gas Heat Section 48DK034 044 Units 60...
Page 61: ...Fig 69 Gas Heat Section 48DK054 074 Units 61...
Page 62: ...Fig 70 Typical Wiring Schematic 48 50DJ 50DW Units 054 074 Shown 62...
Page 63: ...Fig 70 Typical Wiring Schematic 48 50DJ 50DW Units 054 074 Shown cont 63...
Page 64: ...Fig 71 Typical Wiring Schematic 48 50DK 50DY Units 054 074 Shown 64...
Page 65: ...Fig 71 Typical Wiring Schematic 48 50DK 50DY Units 054 074 Shown cont 65...
Page 66: ...Fig 72 Typical Control Wiring Schematic 48 50NP 50NB Units 054 074 Shown 66...
Page 67: ...Fig 72 Typical Control Wiring Schematic 48 50NP 50NB Units 054 074 Shown cont 67...
Page 68: ...Fig 72 Typical Control Wiring Schematic 48 50NP 50NB Units 054 074 Shown cont 68...
Page 69: ...Fig 73 Typical Power Wiring Schematic 48 50NP 50NB Units 054 074 208 230 and 460 v Shown 69...
Page 71: ......