STEP
ACTION
YES
NO
GO TO
5
Return setup switch SW1-2 to its original setting and go to
page number indicated in the Index for the section covering
the status code.
INDEX
6
Jumper R and W/W1 thermostat terminals.
7
7
Observe the furnace operation for 25 minutes or until status
code starts flashing.
8
8
Does status code 33 flash?
40
9
9
Does a different status code flash?
5
27
10
Return setup switch SW1-2 to its original setting and go to
page number indicated in Index for CLEANUP AND
START-UP INSTRUCTIONS.
INDEX
11
Is 24-vac across connector terminal PL1-6 and C
OM
-24V on
variable speed furnace control?
13
12
12
Replace the variable speed furnace control.
10
13
Is 24-vac across connector terminal PL1-8 and C
OM
-24V on
variable speed furnace control?
12
14
14
Turn power off.
15
15
Do you have continuity across limit switch LS?
19
16
16
Wait for unit to cool then recheck for continuity across limit
switch LS.
17
17
Do you have continuity across limit switch LS?
19
18
18
Replace limit switch.
10
19
Do you have continuity across the flame rollout switch
FRS?
35
20
20
Can flame rollout switch FRS be reset?
22
21
21
Replace flame rollout switch FRS.
10
22
Reset flame rollout switch FRS, turn power on, and observe
furnace operation for (2) 15 minute cycles.
23
23
Does flame rollout switch FRS trip again?
25
24
24
Does a different status code flash?
5
10
25
You have inadequate combustion-air supply. This may be
caused by:
- Reversed vent and combustion-air pipes.
- Poor burner, manifold, or orifice alignment.
- Blocked heat exchanger.
- Leak in secondary heat exchanger.
- Leak somewhere between primary and secondary heat
exchangers.
26
26
Fix problem.
10
27
While the unit is operating in low heat jumper R and W2.
28
28
Observe furnace operation for another 10 minutes or until
status code 33 starts flashing.
29
29
Does status code 33 flash?
50
30
30
Does a different status code flash?
5
31
31
Is the furnace in the downflow or horizontal position?
32
10
32
Disconnect the R thermostat lead, wait for blower to stop,
and continue to observe furnace for 5 minutes.
33
33
Does fault occur after blower stops?
34
10
34
Increase the blower off-delay time to 180 seconds by put-
ting both setup switches SW1-7 and SW1-8 into the ON
position.
26
35
Turn power on.
36
36
Does status code 33 flash?
38
37
37
Does a different status code flash?
5
6
38
You have an open RED wire or bad terminal in limit circuit.
Repair wire or replace harness.
10
39
Does furnace have the proper limit switch, limit shield,
blower baffle (if used), and rear air baffle (if used)? If so,
are the limit switch, limit shield, and heat exchangers prop-
erly aligned?
40
26
40
Remove tape from door switch, turn power off at main dis-
connect, and remove jumper across R and W/W1.
41
41
Is the blower wheel firmly mounted on motor shaft?
42
26
42
Does the model plug PL4 match the part number specified
on the Model Plug Chart in the upper left hand corner of
wiring schematic?
44
43
43
Replace model plug.
10
25