Lennox HP21 User Manual

Page 52
TABLE 20b
CONTINUED FROM A ON PREVIOUS PAGE CONTINUED FROM B ON PREVIOUS PAGE
CHECK VOLTAGE ACROSS TERMINALS Y1 AND X
AND Y2 AND X AT UNIT LOW VOLTAGE TERMINAL
STRIP TB15. IS VOLTAGE 24+
6VAC?
CHECK VOLTAGE ACROSS TERMINALS Y1 AND X
AT UNIT LOW VOLTAGE TERMINAL STRIP TB15.
IS VOLTAGE 24+
6VAC?
YESNO YES NO
CHECK INDOOR THERMOSTAT
FOR MALFUNCTIONS.
REPLACE IF NECESSARY.
REPEAT
TROUBLESHOOTING
PROCEDURE.
CHECK VOLTAGE AT CONTACTOR COILS.
FOR SINGLE PHASE UNITS,
K1 AND K69 SHOULD BE ENERGIZED.
FOR THREE PHASE UNITS,
K1 ONLY SHOULD BE ENERGIZED.
IS VOLTAGE 24+
6VAC?
CHECK VOLTAGE AT CONTACTOR COILS.
FOR SINGLE PHASE UNITS,
K69 ONLY SHOULD BE ENERGIZED.
FOR THREE PHASE UNITS,
K1 ONLY SHOULD BE ENERGIZED.
IS VOLTAGE 24+
6VAC?
YES NO
IS CONTACTOR(S) COIL
ENERGIZED?
IS CONTACTOR(S) COIL
ENERGIZED?
CHECK INDOOR THERMOSTAT
FOR MALFUNCTIONS.
REPLACE IF NECESSARY.
REPEAT
TROUBLESHOOTING
PROCEDURE.
CHECK SECONDARY (OUTPUT) VOLTAGE OF
THE TRANSFORMER IN THE OUTDOOR UNIT
IS VOLTAGE 24+
6VAC?
YESNO
IS FUSE PROVIDED IN TRANS-
FORMER SECONDARY?
YESNO
IS FUSE
O.K.?
YESNO
REPLACE
FUSE.
REPEAT
TROUBLESHOOTING
PROCEDURE.
YES NO
REPLACE
TRANSFORMER.
REPEAT
TROUBLESHOOT-
ING PROCEDURE.
CHECK LINE
VOLTAGE WIRING.
REPEAT
TROUBLESHOOTING
PROCEDURE.
YES NO
REPLACE CONTACTOR.
REPEAT
TROUBLESHOOTING
PROCEDURE.
ARE CONTACTS CLOSING?
NO
CHECK PRIMARY (INPUT) VOLTAGE OF
THE TRANSFORMER IN THE OUTDOOR UNIT
IS MEASURED VOLTAGE SAME AS VOLTAGE
ON UNITS RATING PLATE?
YES
CHECK STARTING CIRCUIT
AND COMPRESSOR.
REPAIR OR REPLACE AS NECESSARY.
REPEAT
TROUBLESHOOTING
PROCEDURE.
YESNO
REPLACE CONTACTOR.
REPEAT
TROUBLESHOOTING
PROCEDURE.
YESNO
ARE CONTACTS
CLOSING?
NO
YES
CHECK STARTING
CIRCUIT AND
COMPRESSOR.
REPAIR OR
REPLACE AS
NECESSARY.
REPEAT
TROUBLESHOOTING
PROCEDURE.
CHECK SWITCHES S4 AND
S40 FOR MALFUNCTIONS.
REPLACE IF NECESSARY.
REPEAT
TROUBLESHOOTING
PROCEDURE.
YES
NO
YES
CHECK VOLTAGE ACROSS
PINS 1 AND 2 OF JP44.
IS VOLTAGE 24+
6VAC?
NO
CHECK WIRING
CONNECTIONS.
REPEAT
TROUBLESHOOTING
PROCEDURE.
IS RESISTANCE WITHIN RE-
SET RANGE LISTED ON UNIT
RATING PLATE?
YES NO
RECONNECT RED
WIRES (TO S1 AND S2)
AND RECONNECT JP44.
RED WIRES ARE NOT
POLARITY SENSITIVE.
ALLOW COMPRESSOR
SUFFICIENT TIME TO
COOL TO RESET TEM-
PERATURE.
1− TURN OFF POWER TO INDOOR AND OUT-
DOOR UNITS.
2− DISCONNECT TWO RED WIRES FROM
TERMINALS S1 AND S2 OF TSC.
3− CHECK THE COMPRESSOR INTERNAL
SENSORS BY CHECKING THE RE-
SISTANCE (OHMS) THROUGH THE RED
WIRES.
CAUTION-THE RED WIRES (S1 AND S2)
MUST BE DISCONNECTED FROM THE TSC
FOR THIS TEST OR DAMAGE TO THE TSC
COULD RESULT.
RECONNECT RED WIRES (TO S1
AND S2) AND RECONNECT JP44.
RED WIRES ARE NOT POLARITY
SENSITIVE. REPEAT TROUBLE-
SHOOTING PROCEDURE.
CHECK INTERNAL WINDINGS
OF COMPRESSOR WITH
OHMMETER. ARE WINDINGS
OPEN OR SHORTED?
YESNO
REPLACE
COMPRESSOR.
REPLACE
TSC.
REPEAT TROUBLESHOOTING PROCEDURE.
1− TURN OFF POWER TO INDOOR AND OUTDOOR
UNITS.
2− DISCONNECT JACKPLUG JP44 FROM TSC.
3− TURN ON POWER TO OUTDOOR UNIT.
4− CHECK VOLTAGE ACROSS TERMINALS 2 AND
7 OF JACKPLUG JP44. IS VOLTAGE 24+
6VAC?

Lennox HP21 Specifications

General

Brand	Lennox
Model	HP21
Category	Heat Pump
Language	English