Lennox Harmony II Zone Control System Installation Instructions Manual page 39

Option 2 − Troubleshooting Harmony
This troubleshooting diagram lists common trouble spots. Rather than providing solutions, this diagram asks questions
about the hookup and operation of system equipment Good troubleshooting skills combined with information provided
elsewhere in this manual are necessary.
n Are thermostats wired correctly?
n Does control center respond appro-
priately to demand?
n Heat pump thermostat used?
(Must not use heat/cool thermo-
stat.)
n If electronic thermostat is used,
does it have relay switching out-
put? If relay with SCR output is
used, isolation relays may need
to be used.
n 24VAC supplied to each thermo-
stat terminal R from control cen-
ter?
n Check each thermostat for output
signal when calling. Heating out-
put? Y1, Y2, W1.
Cooling output? Y1, O, Y2
Blower output not used, no need
to check.
n Are anticipators working?
n Are LEDs on panel lit? Check
wiring?
n Does panel readily switch be-
tween Zone, Central and Off?
n Does panel readily switch be-
tween Cool, Heat and Auto?
n Does panel readily switch be-
tween Fan On and Auto?
n Are wires run adjacent to AC
line voltage wires?
n Is switch installed in compres-
sor discharge line between
compressor and reversing
valve?
n Does switch open when high
pressure condition is simulated
(temporarily blocking airflow in
heating mode)?
n Does control center respond
appropriately when high pres-
sure condition is simulated
(temporarily disconnecting
switch simulates high pres-
sure).
n Is discharge probe installed?
n Probe should be located in discharge air
plenum before first bend or branch. Is
probe in correct location?
n Is it wired correctly?
n After 5 minutes heating operation, is dis-
charge air between 95_F and 125_F?
n After 5 minutes cooling operation, is dis-
charge air between 53_F and 70_F?
®
II Zone Control with Lennox Heat Pump
n Are jumpers set correctly?
n Only one jumper is allowed
per zone.
n Error code present? If so,
see diagnostic section of
this manual.
n Is jumper set correctly? Heating
air reduction must be set to 0%.
n Does jumper provide appropriate
speed reduction? If no, check in-
door unit before replacing control
center.
Figure 30
Page 39
n Line Voltage to transformer?
n 24VAC from transformer to control center?
n Fuses OK?
n Are all wire connections good? Are all wire
connections correct?
or GAS
n Up to two jumpers may be used.
n Is jumper set correctly?
n If two jumpers are used, one must
n Is wiring correct and in good
condition?
n Do dampers respond to de-
mand? 0 volts AC = open.
24 volts AC = closed.
Dampers should drive
closed when 24 volts is
jumpered to damper motor.
n Does control center energize ap-
propriate outputs? During Cool-
ing? During Heating? During De-
frost? During Em. Heat?
n 24VAC from indoor unit trans-
former to R?
n Does indoor unit respond to
outputs? Cooling? Heating?
Defrost? Em. Heat?
n Does blower speed change
as zone demand changes? If
no, does DS output vary from
0 to 25VDC?
n Does outdoor unit respond to
demand?
n Is it operating properly?
n Test defrost. Does outdoor
unit initiate and terminate de-
frost correctly?
n Is W1 energized during de-
frost?
n Does control center respond
appropriately during defrost?
n Are appropriate outputs
energized in response
to demand?
n Is jumper set correctly for
stages of auxiliary heat?
be on a C terminal and the other on
an H terminal.