58SU0A (Series 2 & 3): Troubleshooting Guide
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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START HERE
If a problem exists, the service technician should always begin troubleshooting here.
NOTICE
!
SPECIAL NOTE: All voltmeters are not the same - Your
voltage readings may vary. This applies to the entire content
of this troubleshooting manual. They are not absolute
values. Correct 115-VAC voltage, current, and power
measurements cannot be taken on variable speed furnaces
using a true RMS meter.
STEP ACTION YES NO GO TO
1.
Remove main furnace door first. DO NOT REMOVE BLOWER ACCESS PANEL! Record status of AMBER LED. See
Service/Status Code Instructions.
Is AMBER LED status light on?
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2. Is the AMBER LED status light blinking rapidly without a pause? 3 4
3. Go to the page number indicated in the Index for RAPID FLASHING LED. INDEX
4. Is the AMBER LED status light blinking ON/OFF slowly with a combination of short and long flashes? 5 7
5.
Determine status code. The status code is a 2-digit number with the first digit determined by the number of short
flashes and the second digit by the number of long flashes.
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6. Go to page number indicated in the Index for the section covering the status code. INDEX
7.
To retrieve previous codes, no thermostat inputs to the control must be present and all time-delays must have
expired. Disconnect the R thermostat lead from the furnace control board and wait for the blower to turn off if it is
running. Briefly (2-3 seconds) remove then reconnect one main limit or draft safeguard wire to display stored status
code. Previous status codes may also be recalled by momentarily shorting the TEST/TWIN terminal to Com24V
terminal until the LED goes out. After status code recall is completed, component self-test will occur.
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8.
Was there a previous status code other than code 11?
Note: Status codes are erased after 72 hours
9 10
9. Go to page number indicated in the Index for the section covering the first previous status code. INDEX
10.
Reconnect the R thermostat lead, set the thermostat fan control to AUTO position if equipped, and set the
thermostat to call for heat.
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11. Does the furnace respond to the call for heat? 12 25
12. Observe operation of furnace for 20 minutes or until AMBER LED status light starts blinking. 13
13. Does the AMBER LED status light blink ON/OFF slowly with a combination of short and long flashes? 5 14
14.
Is the temperature rise above or below the range specified on the rating plate when the unit is operating?
Refer to the Start-Up and Adjustment section in the Installation, Start-Up, and Operating Instructions.
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15. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. INDEX
16. Make sure power is being supplied to the furnace. 17
17.
Check fuses, breakers, or manual disconnects to be sure they are correctly set. If not, reset them and go back to
step 1.
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18. Remove blower access panel and depress door switch. Use a piece of tape to hold switch closed. 19
19. Is 115-VAC across L1 and L2? 21 20
20.
Turn power off. Check continuity of power leads and door switch. If necessary, repair power leads and/or replace
door switch.
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21. Is 24-VAC across SEC-1 and SEC-2? 22 23
22. Replace the furnace control. 18
23. Is 115-VAC across the transformer primary leads? 24 22
24. Replace the transformer. 15
25. Is 24-VAC across W and COM-24V on the furnace control? 27 26
26. You have a defective thermostat, or a break in wiring between thermostat and furnace. Fix problem. 15
27. Disconnect all thermostat leads and jumper R to W. Does the furnace respond to the call for heat? 28 22
28.
You have an incompatible thermostat. Do any of the following:
1. Wire the thermostat C terminal to COM-24V.
2. Isolate the W input with a relay.
3. Install ballast resistor across W and COM-24V.
4. Replace the thermostat with a compatible model.
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