43. | If possible, replace inducer wheel. Otherwise, replace inducer motor assembly. | Ð | Ð | 8 | |
44. | Is there any frost | 45 | 46 | Ð | |
45. | The problem is caused by reversed vent and | Ð | Ð | 14 | |
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→46. | You have inadequate |
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- Excessive restriction in | Ð | Ð | 14 | ||
| - Internal restriction in coupling box or secondary heat exchangers |
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→47. | Replace pressure switch assembly. | Ð | Ð | 70 | |
→48. | Is unit a trophy unit? | 50 | 49 | Ð | |
→49. | Does fault occur before blower motor turns ON? | 47 | 51 | Ð | |
| Replace pressure switch assembly with pressure switch assembly used in |
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→50. | replace furnace control board. If you replace furnace control board make sure replacement control | Ð | Ð | 70 | |
has a date code of 9837 or later. Only replace the pressure switch assembly or the furnace control | |||||
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| board NOT both. |
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→51. | Replace furnace control board. | Ð | Ð | 70 | |
52. | Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. | Ð | Ð | 53 | |
53. | Turn power on and wait several sec before proceeding to next step. | Ð | Ð | 54 | |
54. | Disconnect collector box tube to pressure switch assembly. | Ð | Ð | 55 | |
55. | Jumper R and W/W1 thermostat terminals on furnace control board. | Ð | Ð | 56 | |
56. | Does Fault Code 42 occur within 11 sec after a call for heat? | 57 | 58 | Ð | |
57. | Reconnect collector box tube to pressure switch assembly. | Ð | Ð | 10 | |
58. | Reconnect collector box tube to pressure switch assembly. | Ð | Ð | 36 | |
59. | Go to page number indicated in Index for CLEANUP AND STARTUP INSTRUCTIONS. If problem | Ð | Ð | INDEX | |
persists on an intermittent basis, contact your distributor. | |||||
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60. | Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. | Ð | Ð | 61 | |
61. | Turn power on and wait several sec, then jumper R, W/W1, and W2 thermostat terminals on fur- | Ð | Ð | 62 | |
nace control board. | |||||
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| Does fault occur a few sec after |
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62. | NOTE: Check for 24v between the N.O. (Normally Open) contact on | 63 | 67 | Ð | |
| HPS and Com on furnace control board to know when |
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63. | Turn power off and disconnect jumper wire across R, W/W1, and W2 thermostat terminals. | Ð | Ð | 64 | |
64. | Connect 1 side of a slope manometer with a tee to collector box pressure tap. Connect other side | Ð | Ð | 65 | |
with a tee to gas valve air pressure fitting. Refer to pressure check diagram in Appendix C. | |||||
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65. | Turn power on and wait several sec, then jumper R, W/W1, and W2 thermostat terminals on fur- | Ð | Ð | 66 | |
nace control board. | |||||
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| Do you have more than 1.9 in. wc pressure drop across heat exchangers when |
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66. | switch HPS makes? | 47 | 44 | Ð | |
NOTE: Check for 24v between the N.O. (Normally Open) contact on | |||||
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→67. | Does fault occur a few sec after main burners ignite? | 63 | 68 | Ð | |
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→68. | Observe operation of furnace in high heat for next 8 minutes or until fault occurs. | Ð | Ð | 69 | |
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→69. | Does the fault occur? | 22 | 59 | Ð | |
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→70. | If problem still persists check for internal restriction in coupling box or secondary heat exchangers. | Ð | Ð | 14 | |
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Fault Code 43
PRESSURE SWITCH CALIBRATION FAULTÐIndicates
0.55¬ RPMRPM (high)(low) ¬ 0.90
If this relationship is not within range specified, furnace control board starts flashing fault colde 43, shuts unit down (inducer runs for 15 sec), waits 2 minutes, stops flashing fault code, and restarts heating cycle.
→It can also indicate that the
STEP | ACTION | YES | NO | GO TO | |
1. | Turn power off, remove blower access panel, and disconnect all thermostat leads from furnace con- | Ð | Ð | 2 | |
trol board. | |||||
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2. | Turn power on and depress door switch. Use a piece of tape to hold switch closed. | Ð | Ð | 3 | |
3. | Jumper R, W/W1, and W2 thermostat terminals on furnace control board. | Ð | Ð | 4 |
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