Carrier 58MVP - Manual (Page 16)

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