Carrier 58MVP Troubleshooting Manual page 16

16. Does the installation have a bypass humidifier?
17. Is setup switch SW-3 in ON position?
18. Put setup switch SW-3 in ON position.
Cycle furnace with blower access panel in place and record temperature rise across furnace 6 min-
19.
utes after main burner ignition.
20. Disconnect jumper wire across R and W/W1 thermostat terminals and wait until blower stops.
21. Remove blower access panel and put setup switch SW-3 in OFF position.
Cycle furnace with blower access panel in place and record temperature rise across furnace 6 min-
22.
utes after main burner ignition.
23. Is the temperature rise in Step 22 more than 10°F higher than the temperature rise in Step 19?
24. Disconnect jumper wire across R and W/W1 thermostat terminals and wait until blower stops.
25. Remove blower access panel and put setup switch SW-3 in ON position.
Cycle furnace with blower access panel in place and record the temperature rise across return air
26.
duct before and after the bypass.
27. Is temperature rise from bypass greater than 15°F?
28. The bypass is oversized. Adjust damper or replace with properly sized bypass.
29. Disconnect jumper wire across R and W/W1 thermostat terminals and wait until blower stops.
30. Does the installation have modulating zone dampers?
31. Is setup switch SW-5 in ON position?
32. Put setup switch SW-5 in ON position?
33. Jumper R and W/W1 thermostat terminals on furnace control board.
Does blower recalibrate every minute? Check by monitoring DC voltage across terminals PL3-1
34. RED (+) and PL3-5 BLUE (-). If DC voltage momentarily goes down to 0 vdc approximately every
60 sec after first blower calibration, then blower is recalibating properly.
Disable modulating zone damper system with all dampers in open position except bypass damper.
35.
If the installation is equipped with a bypass damper, it should be in the closed position.
Put setup switch SW-2 in OFF position. Disconnect jumper wire across R and W/W1 thermostat ter-
minals and reset the power. Reconnect jumper wire across R and W/W1 thermostat terminals and
36.
monitor manifold gas pressure while observing furnace operation for 10 minutes.
NOTE: Blower access panel must be in place.
37. Does a Fault Code 33 flash?
The problem is cause by the modulating zone damper system. Install a 2-stage thermostat and let
38. the zone system modulate gas flow. If you still have a problem, check the zone manufacturer's in-
stallation and Troubleshooting Guide for corrective action.
While monitoring manifold pressure in Step 36, did it drop to low-fire manifold pressure during low-
39.
fire operation?
40. Replace gas valve.
Replace blower motor and belly band.
41. NOTE: Torque belly band screw to 80 in.lb (6.7 ft. lb).
WARNING: DO NOT OVERTIGHTEN!
42. Jumper R, W/W1, and W2 thermostat terminals on furnace control board.
Is furnace considerably overfired (10% or more)? Clock input rate. Do not use manifold pressure
43.
method unless using propane.
Ensure gas inlet pressure and burner orifices (natural or propane) are correct. Then adjust gas
44. valve to proper rate per the Installation, Start-Up, and Operating Instructions. If it cannot be ad-
justed to proper rate, replace gas valve.
45. Disconnect jumper wire across R, W/W1, and W2 thermostat terminals and wait until blower stops.
46. Excessive restriction of airflow during locked in high-fire mode caused lockout.
Relieve restriction. Check all dampers, filters, and return-air grilles for blockage. Put setup switch
47.
SW-1 in OFF position.
48. Fix problem.
49. Is temperature rise within 10°F of midpoint of rise range?
50. Is temperature rise within 10°F of midpoint of rise range?
51. Turn power off and install a temperature probe in front of limit switch button.
Turn power on and cycle unit. Does limit switch open at a temperature at least 10°F below tempera-
52. ture setpoint for limit switch. (EXAMPLE: The setpoint is 220°F, but switch opens at a temperature
below 210°F.)
The problem may be related ot poor air distribution. Add turning varies, more supply-air openings,
53.
or more return-air openings. Use Appendix E to evaluate.
16
17 30 —
19 18 —
— — 9
— — 20
— — 21
— — 22
— — 23
24 8 —
— — 25
— — 26
— — 27
28 29 —
— — 9
— — 30
31 51 —
33 32 —
— — 9
— — 34
35 8 —
— — 36
— — 37
39 38 —
— — 9
49 40 —
— — 9
— — 9
— — 43
44 45 —
— — 9
— — 6
— — 47
— — 42
— — 9
51 41 —
51 16 —
— — 52
7 53 —
— — 48