Bryant 333B-AV-036060-AA-JA Troubleshooting Manual page 21

STEP
You have an open circuit between low-heat pressure switch LPS and 2-stage
furnace control. This includes all the ORANGE wire interconnecting low-heat
pressure switch LPS and 2-stage furnace control. It also includes draft safe-
guard switch DSS and auxiliary limit switch(es) ALS1 & 2 (if used).
1. Check continuity across draft safeguard switch DSS and auxiliary limit
switch ALS1 (if used). If there is no continuity across the switch, reset it. If
manual reset switch cannot be reset, replace it.
22. 2. Check continuity across auxiliary limit switch ALS2 (if used). If there is no
continuity across the switch, replace it.
3. Check continuity of each ORANGE wire interconnecting low-heat pressure
switch LPS and 2-stage furnace control. Repair open wire or replace har-
ness.
NOTE: An open circuit between low-heat pressure switch LPS and 2-stage fur-
nace control normally causes status code 43 to occur. Go back to Step 1 after
fixing this problem, because there is another problem.
23. Turn power on and jumper R and W/W1 thermostat terminals.
Do you have 24 vac across YELLOW wire on low-heat pressure switch LPS
24.
and C -24V on 2-stage furnace control?
OM
Do you have 24 vac across connector terminal PL1-5 and C
25.
furnace control?
You have an open wire or bad terminal on YELLOW wire from low-heat pres-
sure switch LPS to 2-stage furnace control. Repair it or replace harness.
26. NOTE: An open circuit in YELLOW wire between low-heat pressure switch LPS
and 2-stage furnace control normally causes status code 43 to occur. Go back
to Step 1 after fixing this problem, because there is another problem.
Replace 2-stage furnace control.
27. NOTE: Go back to Step 1 after replacing 2-stage furnace control, because
there may be an additional problem.
Turn power off and disconnect jumper wire across R and W/W1 thermostat ter-
28.
minals.
Connect 1 side of slope manometer with a tee to collector box pressure tap.
29.
Refer to Pressure Check Diagram in Appendix C.
30. Turn power on. Jumper R and W/W1 thermostat terminals.
Do you have enough pressure across heat exchangers to make low-heat pres-
sure switch LPS when status code 32 flashes? Reference high-altitude settings
if a High-Altitude Pressure Switch Kit is installed. (See Table 3.)
If this is a high-altitude installation and a High-Altitude Pressure Switch Kit is
31.
not installed, replace pressure switch assembly with a High-Altitude Pressure
Switch Kit.
NOTE: High altitude is over 5500 ft for Category I vent and over 4000 ft for Cat-
egory III vent.
32. Replace pressure switch assembly.
33. Is inducer motor rotating in direction indicated on cooling fan?
34. Turn power off.
35. Is inducer wheel okay?
If possible, replace inducer wheel. Otherwise, replace inducer motor assembly.
NOTE: If inducer wheel shows signs of excessive deterioration, find cause by
36.
checking venting, input rates, and temperature rise. If other parts are affected,
replace them.
37. Is inducer wheel properly mounted to inducer motor shaft?
38. Does furnace have proper cell outlet plates and collector box?
39. Fix problem.
You have excessive restriction in vent pipe or excessive leakage before pres-
sure tap in collector box. Check for the following:
• Restriction in vent pipe.
• Proper vent sizing for installation.
40.
• Leakage in collector box.
• Leakage in heat exchanger.
NOTE: If leakage is due to excessive corrosion, find cause by checking venting,
input rates, and temperature rise. If other parts are affected, replace them.
Continue to observe furnace operation for 20 minutes or until status code starts
41.
flashing.
42. Does status code 32 flash?
43. Does a different status code flash?
Turn power off and disconnect jumper wire across R and W/W1 thermostat ter-
44.
minals.
Connect 1 side of slope manometer with a tee to collector box pressure tap.
45.
Refer to Pressure Check Diagram in Appendix C.
46. Turn power on and jumper R and W/W1 thermostat terminals.
ACTION
-24V on 2-stage
OM
—21—
YES NO GO TO
— — 1
— — 24
25 28 —
27 26 —
— — 1
— — 1
— — 29
— — 30
— — 31
32 33 —
— — 8
34 11 —
— — 35
37 36 —
— — 8
38 39 —
40 39 —
— — 8
— — 39
— — 42
44 43 —
7 48 —
— — 45
— — 46
— — 47