Carrier 58MVP Troubleshooting Manual page 30

STEP
The ORANGE wire from low-pressure switch LPS to furnace control board is
20.
not making good connection. Repair wire or replace harness.
Turn power off and disconnect jumper wire across R, W/W1, and W2 thermo-
stat terminals. Disconnect BROWN wire from N.O. (Normally Open) contact on
21.
high-pressure switch HPS. Turn power on and wait a few sec for self test, then
reconnect jumper across R and W/W1 thermostat terminals.
22. Does a Fault Code 32 occur?
Reconnect BROWN wire to N.O. (Normally Open) contact on high-pressure
23.
switch HPS.
The problem may be caused by a sag in vent pipe. If this is not the problem
24.
and fault still occurs, replace pressure switch assembly.
25. The vent tube to drain trap, drain trap, or drain line is clogged.
Fault Code 44
BLOWER CALIBRATION FAULT—This fault indicates that calculated blower motor speed is below 250 or
above 1300 RPM. When Fault Code 44 occurs in HEATING, COOLING, or CONTINUOUS FAN mode, unit
operates as shown below. Keep in mind that whenever furnace control board shuts unit down in heating
mode, gas shuts off immediately, inducer continues running for 15 sec, and blower runs at default (or
previous) speed control signal for selected off delay.
• HEATING—During a call for heat, the desired low-heat and high-heat blower RPMs are calculated at the same time. If desired low-heat
blower RPM is less than 250 or greater than 1300 RPM, furnace control board starts flashing Fault Code 44, shuts unit down, waits 2
minutes, stops flashing Fault Code 44, and restarts heating cycle. If this happens on 2 consecutive cycles, furnace control board locks out
on Fault Code 12. During this sequence, it is possible for furnace control board to start flashing Fault Code 41 instead of Fault Code 44.
This indicates that blower calibration failed and blower speed during off delay is out of range.
When unit is operating in low heat and furnace control board (date code 9505 or earlier) is flashing Fault Code 44, it indicates that desired
high-heat blower RPM is greater than 1300 RPM, and unit remains running in low fire-mode for rest of heating cycle.
When unit is operating in high heat and furnace control board (date code 9506 or later) is flashing Fault Code 44, it indicates that desired
high-heat blower RPM is greater than 1300 RPM, but furnace control board is running blower at default speed of 1200 RPM. Under this
condition, the high-fire temperature rise could be outside rise range and can cause limit cycling to occur.
• COOLING—If desired cooling blower RPM is less than 250 or greater than 1300 RPM, furnace control board starts flashing Fault Code
44 and runs at default (or previous) cooling speed control signal for rest of cooling cycle. During this sequence, it is possible for furnace
control board to start flashing Fault Code 41 instead of Fault Code 44. This indicates that blower calibration failed and blower speed for
cooling is also out of range.
• CONTINUOUS FAN—If desired continuous fan blower RPM is less than 250 or greater than 1300 RPM, furnace control board will start
flashing Fault Code 44 and run at default (or previous) continuous fan speed control signal for the rest of continuous fan cycle. During this
sequence, it is possible for furnace control board to start flashing Fault Code 41 instead of Fault Code 44. When this happens, it indicates
blower calibration failed and blower speed for continuous fan is also out of range.
STEP
Turn power off, wait 30 sec, then restore power. Reset thermostat. Observe op-
1. eration of furnace through 1 heating cycle.
NOTE: Blower access panel must be in place.
2. Does Fault Code 44 flash twice followed by Fault Code 41?
Eventually furnace will lock out on Fault Code 12 given enough time. Go to
3.
page number indicated in Index for Fault Code 12.
4. Does only Fault Code 44 occur?
5. Does a different fault occur?
6. Go to page number indicated in Index for fault code flashed.
Go to page number indicated in Index for CLEANUP AND START-UP
7.
INSTRUCTIONS.
8. Does unit operate in low fire while flashing Fault Code 44?
You have excessive restriction in air delivery system. Check filter(s) and duct-
work. If problem still persists, replace furnace control board. Make sure replace-
9. ment board has a date code of 9506 or later. This new furnace control board
will allow unit to run in high fire when necessary. See description of operation at
start of Fault Code 44. If problem still persists, use Appendix E to evaluate.
10. Fix problem.
30
YES NO GO TO
— — 8
— — 22
17 23 —
— — 24
— — 8
— — 10
YES NO GO TO
— — 2
3 4 —
— — INDEX
8 5 —
6 11 —
— — INDEX
— — INDEX
9 3 —
— — 10
— — 7