Carrier 58MVP - Manual (Page 20)

18.
Do you have continuity between the N.O. (Normally Open) contact on low-pressure switch LPS and
chassis ground?
19 3 —
19. The ORANGE wire from low-pressure switch LPS is shorting to ground. Replace or repair it. — — 9
20. Does Fault Code 24 occur when gas valve GV is energized? 21 28 —
21.
Disconnect jumper wire across R and W/W1 thermostat terminals and replace secondary voltage
fuse.
— — 22
22.
Disconnect BLUE wire to gas valve GV and jumper R and W/W1 thermostat terminals on furnace
control board.
— — 23
23.
Does Fault Code 34 IGNITION PROVING FAULT occur? If not, Fault Code 24 should occur when
BLUE wire is energized.
27 24 —
24. Disconnect PL1 from furnace control board. — — 25
25. Do you have continuity between BLUE wire and chassis ground? 26 3 —
26. The BLUE wire to gas valve GV is shorting to ground. Replace or repair it. — — 9
27. Replace gas valve GV. — — 4
28. Add a jumper across R and W2 thermostat terminals on furnace control board. — — 29
29. Does Fault Code 24 occur when high-pressure switch HPS is energized? 30 39 —
30.
Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and replace secondary volt-
age fuse.
— — 31
31.
Disconnect BROWN wire to gas valve GV and jumper R, W/W1, and W2 thermostat terminals on
furnace control board.
— — 32
32. Does Fault Code 24 occur when high-pressure switch HPS is energized? 33 27 —
33. Disconnect PL1 from furnace control board. — — 34
34. Do you have continuity between BROWN wire and chassis ground? 35 36 —
35. The BROWN wire to gas valve GV is shorting to ground. Replace or repair it. — — 9
36. Disconnect PL2 from furnace control board. — — 37
37.
Do you have continuity between the N.O. (Normally Open) contact on high-pressure switch HPS
and chassis ground?
38 3 —
38. The BROWN wire from high-pressure switch HPS is shorting to ground. Replace or repair it. — — 9
39. Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and wait until blower stops. — — 40
40. Jumper R, G, and Y/Y2 thermostat terminals on furnace control board. — — 41
41. Does Fault Code 24 occur when G and Y/Y2 are energized? 3 42 —
42.
Reconnect all thermostat leads (except HUM terminal if used) to furnace control board and operate
furnace in heating and cooling mode from thermostat.
— — 43
43. Does Fault Code 24 occur during heating cycle? 44 45 —
44. You have a defective thermostat or a short circuit in wiring between thermostat and furnace. — — 9
45. Does Fault Code 24 occur during cooling cycle? 46 47 —
46. You have a defective thermostat or a short circuit in wiring between thermostat and outdoor unit. — — 9
47. Does problem usually occur in cooling mode? 48 49 —
48.
Check outdoor unit contactor. Failure to pull in can cause excessive current draw on low-voltage
circuit. This can be an intermittent problem.
— — 9
49. Reconnect humidifier and check for excessive current draw. — — 9
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