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STEP
47
If possible, replace inducer wheel. Otherwise replace in-
48
49
Is there any frost build-up on combustion-air inlet?
The problem is caused by reversed vent and combustion-air
50
pipes or some other moist air entering combustion-air pipe.
You have excessive restriction in combustion-air or vent
51
Make sure all pins and wire leads are in tact on connectors
52
between variable speed furnace control and the inducer
Replace the inducer motor or the inducer motor assembly.
53
If problem still persists after replacing the inducer motor,
Turn power off and disconnect jumper from the R and
54
Turn power on and jumper the R, W/W1, and W2 thermo-
55
Does fault occur a few seconds after the high heat pressure
Note: Check for 24-vac between the N.O. (Normally Open)
56
contact on high heat pressure switch HPS and Com on the
variable speed furnace control to know when the high heat
Turn power off and disconnect jumper from the R, W/W1,
57
Connect 1 side of slope manometer with a tee to collector
box pressure tap. Connect other side with a tee to gas
58
valve pressure fitting. Refer to pressure check diagram in
Turn power on and jumper the R, W/W1, and W2 thermo-
59
Do you have more than 1.9 in. wc pressure drop across
heat exchangers when high heat pressure switch HPS
60
Note: Check for 24-vac between the N.O. (Normally Open)
contact on high heat pressure switch HPS and Com on the
variable speed furnace control to know when the high heat
Status Code 43
LOW-HEAT PRESSURE SWITCH OPEN WHILE HIGH-HEAT PRESSURE SWITCH IS CLOSED -
can occur as a result of the low heat pressure switch LPS not making during a call for high heat. Keep in mind that whenever status code 43
occurs the variable speed furnace control shuts unit down, turns the inducer off, and gas remains off.
• LOW HEAT PREPURGE - If the high heat pressure switch HPS makes and the low heat pressure switch LPS is still open the variable speed
furnace control starts flashing status code 43, shuts unit down, and waits 2 minutes before restarting the heating cycle.
• HIGH HEAT PREPURGE - If the high heat pressure switch HPS makes and the low heat pressure switch LPS is still open the variable speed
furnace control starts flashing status code 43, shuts unit down, and waits 2 minutes before restarting the heating cycle.
STEP
Turn power off, remove the blower access panel and dis-
1
connect the R thermostat lead from the furnace control
Turn the power on and depress the door switch. Use a
2
3
Jumper the R, W/W1, and W2 thermostat terminals.
4
Observe the operation of the furnace until ignition.
5
6
Go to page number indicated in the Index for the section
7
Go to page number Indicated in Index for CLEANUP AND
8
9
10
ACTION
Is inducer blower wheel okay?
ducer motor assembly.
pipe.
motor.
contact your distributor.
W/W1 thermostat terminals.
stat terminals.
switch HPS makes?
pressure switch HPS makes.
and W2 thermostat terminals.
Appendix C.
stat terminals.
makes?
pressure switch HPS makes.
ACTION
board.
piece of tape to hold switch closed.
Does status code 43 flash?
Does a different status code flash?
covering the status code.
START-UP INSTRUCTIONS.
Are the pressure switches wired correctly?
Fix problem.
YES
49
50
57
45
YES
9
7
11
33
NO
GO TO
48
8
51
15
15
53
8
55
56
8
58
59
60
49
This status code
NO
GO TO
2
3
4
5
6
8
INDEX
INDEX
10
8
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