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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APPENDIX C - Transducer Pressure Check
A230411
Fig. 4 – Pressure Check Connection
STEP ACTION YES NO GO TO
1.
Shut the power off, remove the blower access panel and disconnect the R thermostat lead from the
furnace control board
2
2. Turn the power on and depress the door switch. Use a piece of tape to hold it closed. 3
3. Does a status code flash? 4 5
4. Go to page number indicated in the Index for the section covering the status code. INDEX
5.
Check transducer supply voltage. To do this, connect a DC voltmeter across terminals PL12-2 GREEN (-)
and PL12-1 RED (+).
6
6. Do you have approximately 12 VDC across terminals PL12-2 GREEN (-) and PL12-1 RED(+)? 11 7
7. Connect a DC voltmeter across terminals and PL3-2 GREEN (-) and PL3-1 RED (+) 8
8. Do you have approximately 12 VDC across terminals PL3-2 GREEN (-) and PL3-1 RED(+)? 9 10
9.
You have an open wire on either the red or green transducer wiring. Repair or replace transducer wiring
harness
16
10. Replace Furnace control 16
11.
Check the transducer output signal. To do this, connect a DC voltmeter across terminals PL12-2 GREEN
and PL12-3 BLACK (+).
12
12. Do you have more than 0.65VDC? 13 17
13. Unplug the pressure hose from its connection at the transducer 14
14. Do you measure more than 0.65VDC? 15 17
15. Replace the transducer 16
16. Fix Problem 25
17.
Connect 1 side of a slope manometer with a tee to the collector box pressure tap. Refer to pressure check
connection illustration in APPENDIX C
18
18.
Run COMPONENT TEST by briefly shorting the TEST/TWIN terminal to the C terminal at the thermostat
terminal strip.
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19.
Referencing the Voltage/Pressure graph located in APPENDIX D, compare the pressure from the slope
manometer to the output signal voltage from the transducer.
EXAMPLE: The graph illustrates that at 1" of negative pressure, the transducer output should be
approximately 1.5 VDC. At 3" of negative pressure, the transducer output should be approximately 3.5
VDC.
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20. Is the transducer VDC output within +/- 0.15 VDC of expected value? 21 15
21. Jumper R and W thermostat terminals and allow furnace to operate for (2) 20 minute cycles. 22
22. Remove jumper from R and W thermostat terminals 23
23. Repeat the transducer check sequence starting at step 11 - 21. 24
24.
Is the transducer VDC output within +/- 0.15 VDC of expected values at pressure and while inducer is
running for component self-test?
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25. Go to page number Indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. INDEX
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