Red Led2 Flashing - Carrier 58MVP Troubleshooting Manual

28. Put setup switch SW-1 back in OFF position.
29. Jumper R and W/W1 thermostat terminals.
30. Does RED LED2 turn back ON?
31. Install isolation relays in the W/W1 and Y/Y2 circuits per Fig. 5 in Appendix B or replace thermostat.
32. Was RED LED2 ON before you started Step 1?
Solid YELLOW LED3 indicates furnace is in high fire and solid GREEN LED4 indicates furnace is in
33.
low fire.
Check outdoor unit contactor. Failure to pull in can cause excessive current draw on low-voltage
34. circuit. This can be intermittent and may require extended operation to repeat problem. Isolating
outdoor unit may solve problem. (See Fig. 6 in Appendix B.)
Check thermostat wire gage between furnace and outdoor unit. It is recommended that AWG No.
35. 18 color-coded copper thermostat wire be used for lengths up to 100 ft. For wire lengths over 100
ft, use AWG No. 16 wire.
Observe operation of furnace through a 20 minute heat cycle. Try to pinpoint where in cycle RED
36.
LED2 turns ON.
Go to step indicated below if RED LED2 turns ON when 1 of the following events occur:
• When gas valve is energized.
37. • When HSI is energized.
• When high-pressure switch HPS makes during transition from low to high fire.
• RED LED2 never turns ON.
38. Replace gas valve.
39. Isolate humidifier with a separate 24-vac supply or replace humidifier solenoid coil.
40. Observe operation of furnace through a 4 minute cooling cycle. Does RED LED2 turn ON?
41. Disconnect all thermostat leads from furnace control board.
Put setup switch SW-1 in ON position and jumper R, W/W1, and Y/Y2 thermostat terminals simulta-
42.
neously until RED LED2 turns OFF.
43. Put setup switch SW-1 back in OFF position.
44. Reconnect only outdoor unit to Y/Y2 and Com terminals on furnace control board.
45. Jumper R and Y/Y2 thermostat terminals.
46. Does RED LED2 turn back ON?
Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. If problem
47. persists on an intermittent basis, replace furnace control board. If problem still persists on an inter-
mittent basis after replacing furnace control board, contact your distributor.
RED LED2 FLASHING—Indicates line voltage polarity is reversed.
STEP
Turn power off, remove blower access panel, and disconnect all thermostat leads from furnace con-
1.
trol board.
2. Turn power on and depress door switch. Use a piece of tape to hold switch closed.
3. Is RED LED2 flashing?
4. Replace furnace control board, date code 9405 or later.
5. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.
6. Do you have 120 vac across L2 and chassis ground?
7. Line voltage polarity is reversed. Fix problem.
8. Replace furnace control board.
ACTION
12
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YES NO GO TO
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