Carrier 48/50PD05 manual Heating Troubleshooting, Variable Frequency Drive VFD Troubleshooting

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.)

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.

48/50PD

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.

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	FUNCTION
On Continuously	Relay contact closed (normal operation).
Blinking	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).

Table 12 — Gas Heating Service Analysis

	PROBLEM		CAUSE	REMEDY
Burners Will Not Ignite.			Unit is not configured for heat.	Check heating configurations using ComfortLinkt Scrolling
				Marquee.
			Active alarm.	Check active alarms using ComfortLinkt Scrolling Marquee and
				the IGC alert flash codes.
			No power to unit.	Check power supply, fuses, wiring, and circuit breakers.
			No power to IGC.	Check fuses and plugs.
			Heaters off due to time guard to prevent short	Check active alarms using ComfortLinkt Scrolling Marquee and
			cycling.	the IGC alert flash codes.
			Occupancy schedule set point not calling for	Check using ComfortLinkt Scrolling Marquee.
			Heating.
			No gas at main burners.	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.
			Water in gas line.	Drain water and install drip.
Inadequate Heating.			Dirty air filters.	Replace air filters.
			Gas input too low.	Check gas pressure at manifold. Refer to gas valve adjustment in
				the Service section.
			Occupancy schedule set point set too low.	Check setpoints and adjust if necessary.
			Unit undersized for load.	Decrease load or increase of size of unit.
			Restricted or low airflow.	Remove restriction, verify proper fan speed operation, and check
				SAT compared to the SAT heating limits.
			Too much outdoor air.	Check economizer position and configuration. Adjust minimum
				position if needed using ComfortLink Scrolling Marquee. Verify
				proper fan speed operation.
			Limit switch cycles main burners.	Check rotation of blower and temperature rise of unit. Adjust as
				needed.
Poor Flame			Incomplete combustion (lack of combustion air)	Check all screws around flue outlets and burner compartment.
Characteristics.			results in: Aldehyde odors, CO, sooting flame, or	Tighten as necessary.
			floating flame.
				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.
Burners Will Not Turn Off.			Unit is in Minimum on---time.	Check using ComfortLinkt Scrolling Marquee and the IGC alert
				flash codes.
			Unit running in Service Test mode.	Check using ComfortLinkt Scrolling Marquee.
			Main gas valve stuck.	Turn off gas supply and unit power. Replace gas valve.
LEGEND
IGC	-	Integrated Gas Controller
SAT	-	Supply Air Temperature

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