Code 13 Limit Switch Lockout; Fault Code 13-Limit Switch Lockout - Carrier 58MVP Troubleshooting Manual

Wait at least 5 minutes after disconnecting line voltage from
equipment before opening blower motor to prevent electric
shock which can cause personal injury or death.
44. Remove tape from door switch and turn power off at main disconnect.
45. Disconnect PL10 from blower assembly.
46. Remove control box assembly from blower shelf and position out of the way.
47. Remove blower assembly from furnace.
Disconnect both multi-pin connectors from blower control module attached to the blower motor. Be
48.
sure to depress release latches on connectors or they may get damaged.
Remove two 1/4-in. hex head bolts from blower control module attached to blower motor. DO NOT
49.
REMOVE TORX HEAD SCREWS located next to 1/4-in. hex head bolts.
Carefully lift blower control module off blower motor. Depress latch on internal connector to discon-
50. nect blower control module from motor portion of blower motor. DO NOT PULL ON WIRES. GRIP
PLUG ONLY.
When blower control module is completely detached from blower motor, verify with standard ohm-
meter that the resistance from each motor lead in motor plug to unpainted motor end plate is
greater than 100k ohms. Then verify motor windings are not shorted or open by measuring resis-
51.
tance between each combination of pins in motor plug (there are three different combinations, pin
1-2, pin 2-3, and pin 1-3). Resistance should be approximately equal across each combination of
pins.
52. Did the motor pass the resistance check?
53. Does blower wheel turn freely with blower control module removed?
Replace blower control module. Inspect failed blower control module for water damage. If present,
54.
find source of water and fix. Check A-coil and/or humidifier.
Replace entire blower motor including blower control module. Inspect blower control module for wa-
55.
ter damage. If present, find source of water and fix. Check A-coil and/or humidifier.
Fault Code 13
LIMIT SWITCH LOCKOUT—This fault indicates the limit switch has tripped 10 times in a row in high fire or 3
times in a row in low fire during a call for heat. Control will auto-reset in 3 hr.
NOTE: After 2 low-fire limit trips, the control is locked into high-heat mode; however, a third low-heat cycle can be forced due to excessive
restriction in air delivery system.
NOTE: Boards with date codes of 9506 or later will lock into high-heat mode after 2 low-fire limit trips and CANNOT be forced into a third
low-heat cycle. Therefore, units with these boards can only lock out if the limit switch trips 10 times in a row in high fire during a call for heat.
STEP
Turn power off and remove blower access panel. Disconnect all thermostat leads from furnace con-
1.
trol board.
2. Depress door switch. Use a piece of tape to hold switch closed.
3. Put setup switch SW-1 in ON position.
Is a Fault Code 44 present in the fault history.
4. NOTE: Read fault codes until they repeat. The last fault code that occurred will flash first fol-
lowed by the lowest number fault code. (EXAMPLE: 13, 13, 44)
5. Put setup switch SW-1 in OFF position.
Does furnace have proper limit switch, limit shield, blower baffle (if used), and rear air baffle (if
6.
used)? If so are limit switch, limit shield, and heat exchangers properly aligned?
7. Replace limit switch.
8. Replace furnace control board.
9. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
10. Put setup switch SW-2 in ON position.
11. Jumper R and W/W1 thermostat terminals on furnace control board.
Is furnace considerably overfired (10% or more)? Clock input rate. Do not use manifold pressure
12.
method unless using propane.
Ensure gas inlet pressure and burner orifices (natural or propane) are correct. Then adjust gas
13. valve to proper rate per Installation, Start-Up, and Operating Instructions. If it cannot be adjusted to
proper rate, replace gas valve.
Is the personality connector PL5 properly wired per furnace model sizing chart in upper left-hand
14.
corner of wiring schematic?
15. Replace or rewire personality connector.
ACTION
15
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53 55 —
54 55 —
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YES NO GO TO
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46 5 —
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10 48 —
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— — INDEX
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13 14 —
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