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STEP
You have an open wire or bad terminal on the BROWN
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wire from the high heat pressure switch HPS to the variable
Turn power off and disconnect jumper wire across R,
20
Connect 1 side of slope manometer with a tee to collector
box pressure tap. Connect other side with a tee to gas
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valve pressure fitting. Refer to pressure check diagram in
Turn power on and jumper R, W/W1, and W2 thermostat
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Do you have atleast 1.90 in. wc pressure drop across heat
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exchangers when status code 31 flashes?
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Replace the pressure switch assembly.
Is inducer motor rotating in direction indicated on inducer
25
26
Replace inducer motor or inducer motor assembly.
27
28
If possible, replace inducer wheel. Otherwise, replace in-
29
Is the inducer wheel properly mounted to the inducer motor
30
31
Is there any frost build-up on the combustion-air inlet?
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You have excessive restriction in combustion-air or vent
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pipe. Also check for proper vent sizing for installation.
Continue to observe furnace operation for 20 minutes or
34
35
36
Turn power off and disconnect jumper wire across R,
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Connect 1 side of slope manometer with a tee to collector
box pressure tap. Connect other side with a tee to gas
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valve pressure fitting. Refer to pressure check diagram in
Turn power on and jumper R, W/W1, and W2 thermostat
39
Monitor slope manometer. Does the pressure reading ap-
40
Replace pressure switch assembly. If problem persists,
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check wiring for an intermittent connection in high heat
Check for a sag in vent pipe or partially clogged drain trap
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or line. Also check for improperly plumbed drainage tubing
Disconnect jumper wire across R, W/W1, and W2 thermo-
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stat terminals and wait for the blower off-delay to finish.
Reset the power and jumper R and W/W1 thermostat termi-
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45
46
Turn power off and disconnect the GRAY wire to the high
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Turn power ON and jumper R and W/W1 thermostat termi-
48
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The BROWN wire is shorting to the ORANGE wire that
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goes the low heat pressure switch LPS. Reconnect the
GRAY wire to the high heat pressure switch HPS.
ACTION
speed furnace control.
W/W1, and W2 thermostat terminals.
Appendix C.
terminals.
housing?
Turn power off.
Is inducer wheel okay?
ducer motor assembly.
shaft?
Fix problem.
until status code starts flashing.
Does status code 31 flash?
Does a different status code flash?
W/W1, and W2 thermostat terminals.
Appendix C.
terminals.
pear to be stable when fault occurs?
pressure switch HPS circuit.
within furnace.
nals.
Does status code 31 flash?
Does a different status code flash?
heat pressure switch HPS.
nals.
Does status code 31 flash?
YES
24
27
30
31
14
37
7
41
47
7
50
22
NO
GO TO
12
21
22
23
25
8
26
8
28
29
8
32
33
8
32
35
36
43
38
39
40
42
8
8
44
45
46
8
48
49
13
12
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