18
25 INVALID MODEL SELECTION OR
SETUP ERROR – If status code 25 only
flashes 4 times on power-up the control
is missing its model plug PL4 and is
defaulting to the model selection stored
in memory. If status code 25 flashes
continuously it could indicate any of the
following:
- Model plug PL4 is missing and there
is no valid model stored in permanent
memory. This will happen if you forget
to install the model plug PL4 on a
service replacement control.
- Thermostat call with SW1-1 ON.
- Thermostat call with SW1-6 ON.
- SW1-1 and SW1-6 both ON.
- Two different furnace models twinned.
31 HIGH-HEAT PRESSURE SWITCH OR
RELAY DID NOT CLOSE OR
REOPENED - Check for:
- Control relay may be defective.
- Gas valve is miswired.
- See status code 32.
41 BLOWER MOTOR FAULT – Indicates the
blower failed to reach 250 RPM or the
blower failed to communicate within the
prescribed time limits. Thirty seconds
after being turned ON or ten seconds
during steady-state operation. Turn power
off and check the following items first
before proceeding to the next step.
- Rubbing blower wheel.
- Loose blower wheel.
- Wiring from furnace control to blower
motor.
Remove the R thermostat connection
from the furnace control, disconnect both
connectors from the blower motor PL13
and PL14. Does the blower wheel turn
freely?
Replace the blower control module attached
to the blower motor. Follow the instructions
with the blower control module to make sure
the entire blower motor does not need to be
replaced.
You have an open wire or bad terminal on the
BLUE wire between the furnace control and
the blower motor.
Replace the furnace control.
Connect a DC voltmeter across PL3-4 BLUE
(+) and PL3-2 GREEN (-). Does the voltage
fluctuate as described two steps back?
Does the voltage fluctuate as described in the
previous step?
Replace the blower control module attached
to the blower motor. Follow the instructions
with the blower control module to make sure
the entire blower motor does not need to be
replaced.
Turn power back on. Is there 115VAC at
PL14-5 and PL14-4?
Is there 12-VDC at PL13-7 RED (+) and PL13-
1 GREEN (-)?
Is there 12-VDC at PL3-1 RED (+) and PL3-
2 GREEN (-)?
Replace the furnace control.
Is there 5-VDC at PL13-16 YELLOW (+) and
PL13-1 GREEN (-)?
The voltage just measured should be very
stable and should not fluctuate more than
.02-VDC. If the voltage fluctuates more than
this get a different voltmeter before
proceeding.
Turn power off, reconnect PL13 and PL14 to
the blower motor, then turn power back on.
Connect a DC voltmeter across PL3-3
YELLOW (+) and PL3-2 GREEN (-). Does
the voltage fluctuate more than it did in the
previous step?
Turn power off, disconnect PL13 and PL14
from the blower motor, then turn power back
on. Connect a DC voltmeter across PL13-
16 BLUE (+) and PL13-1 GREEN (-). The
voltage should be near 0-VDC but it will
fluctuate briefly several times a second. If
you have an analog voltmeter the needle will
briefly go high several times a second. If you
have a digital voltmeter with a bar graph it
will show a large change in magnitude on
the bar graph several times a second. If you
have a standard digital voltmeter it will show
a brief fluctuation in voltage and the
magnitude may vary depending on the
voltmeter used.
You have an open wire or bad terminal on
either the BLACK or WHITE power leads
between the furnace control and the blower
motor. If you have a power choke disconnect
it and check continuity.
You have an open wire or bad terminal on
either the RED or GREEN wire between the
furnace control and the blower motor.
Is there 5-VDC at PL3-3 YELLOW (+) and
PL3-2 GREEN (-)?
You have an open wire or bad terminal on the
YELLOW wire between the furnace control
and the blower motor.
YES
NO
NO
NO
YES
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
YES
YES
NO
42 INDUCER MOTOR FAULT- Indicates the
inducer motor has not started within 20
seconds after a call for heat, the inducer
motor RPM is outside its valid range of
operation, or the inducer RPM signal was
lost for 5 seconds during operation.
Check for:
- Proper vent sizing.
- Failed inducer motor.
- Restricted combustion air supply
- Improper motor wiring.
- Service replacement control does not
recognize new model plugs HK70EZ057
thru HK70EZ061. Control board with
date code 3106 or later required.
A06461
355BAV
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