Heating Troubleshooting; Variable Frequency Drive (Vfd) Troubleshooting; Phase Loss Protection - Carrier 48/50PD05 User Manual

Heating Troubleshooting

Use the unit Scrolling Marquee display or a CCN device to view
the heating status display and the heating diagnostic display (see
Appendix A) for information on the heating operation. Check the
current alarms and alarm history for any heating alarm codes and
correct any causes. (See Table 12.) Verify any unique control
configurations per installed site requirements or accessories. If
alarms conditions are corrected and cleared, operation of the heat
stages and indoor fan may be verified by using the Service Test
mode. (See Table 5.)
Gas Heat (48PD Units Only)
See Table 12 for general gas heating service analysis. See Fig. 9 for
service analysis of the IGC board logic. Check the status LED on
the IGC board for any flashing alarm codes and correct any causes.
(See Table 13.)
Electric Heat (50PD Units Only)
See Table 14 for electric heating service analysis.

Variable Frequency Drive (VFD) Troubleshooting

The VFD must be in "Auto" mode and when commanding it to
100% the voltage signal should be 10vdc across AI1 and AIGND.
Verify all parameters are correct to factory defaults. See Appendix
B for parameters and additional troubleshooting.

Phase Loss Protection

The phase loss protection option will monitor the three-phase
electrical system to provide phase reversal and phase loss
protection.
PROBLEM
Burners Will Not Ignite. Unit is not configured for heat.
Active alarm.
No power to unit.
No power to IGC.
Heaters off due to time guard to prevent short
cycling.
Occupancy schedule set point not calling for
Heating.
No gas at main burners.
Water in gas line.
Inadequate Heating. Dirty air filters.
Gas input too low.
Occupancy schedule set point set too low.
Unit undersized for load.
Restricted or low airflow.
Too much outdoor air.
Limit switch cycles main burners.
Poor Flame
Incomplete combustion (lack of combustion air)
Characteristics. results in: Aldehyde odors, CO, sooting flame, or
floating flame.
Burners Will Not Turn Off. Unit is in Minimum on --- time.
Unit running in Service Test mode.
Main gas valve stuck.
LEGEND
IGC - - Integrated Gas Controller
SAT - - Supply Air Temperature
Phase Reversal Protection
If the control senses an incorrect phase relationship, the relay (K1)
will be de-energized (opening its contact). If the phase relationship
is correct, the relay will be energized. The control has a self-bypass
function after a pre-set time. If the control determines that the three
phases stay in a correct relationship for 10 consecutive minutes, the
relay will stay energized regardless of the phase sequence of three
inputs as long as 24-vac control voltage is applied. This self-bypass
function will be reset if all three phases are restored in a phase loss
event.
Phase Loss Protection
If the reverse rotation board senses any one of the three phase
inputs has no AC voltage, the relay will be de- -energized (opening
its contact). This protection is always active as long as 24-vac
control voltage is applied, and is not affected by the self by-pass
function of the phase sequence monitoring function. However, in
the event of phase loss, the relay will be re-energized only if all
three phases are restored and the three phases are in the correct
sequence.
A red LED is provided to indicate the function of the board. See
the table below.
LED STATUS
On Continuously
Blinking
Table 12 — Gas Heating Service Analysis
CAUSE
34
FUNCTION
Relay contact closed (normal operation).
Relay contact open (phase loss or phase
reversal has occurred) --- No power will be
supplied to the control system.
Off 24 vac control power not present (off).
REMEDY
Check heating configurations using ComfortLinkt Scrolling
Marquee.
Check active alarms using ComfortLinkt Scrolling Marquee and
the IGC alert flash codes.
Check power supply, fuses, wiring, and circuit breakers.
Check fuses and plugs.
Check active alarms using ComfortLinkt Scrolling Marquee and
the IGC alert flash codes.
Check using ComfortLinkt Scrolling Marquee.
Check gas line for air and purge as necessary. After purging gas
line of air, allow gas to dissipate for at least 5 minutes before
attempting to re--- light unit.
Drain water and install drip.
Replace air filters.
Check gas pressure at manifold. Refer to gas valve adjustment in
the Service section.
Check setpoints and adjust if necessary.
Decrease load or increase of size of unit.
Remove restriction, verify proper fan speed operation, and check
SAT compared to the SAT heating limits.
Check economizer position and configuration. Adjust minimum
position if needed using ComfortLink Scrolling Marquee. Verify
proper fan speed operation.
Check rotation of blower and temperature rise of unit. Adjust as
needed.
Check all screws around flue outlets and burner compartment.
Tighten as necessary.
Cracked heat exchanger, replace.
Unit is over--- fired, reduce input. Adjust gas line or manifold
pressure.
Check vent for restriction. Clean as necessary.
Check orifice to burner alignment.
Check using ComfortLinkt Scrolling Marquee and the IGC alert
flash codes.
Check using ComfortLinkt Scrolling Marquee.
Turn off gas supply and unit power. Replace gas valve.