Carrier 48TJF008-012, 48TJE008-014, 48TJD008-014 Heating Service Troubleshooting

Table 21 Ð Heating Service Troubleshooting

PROBLEM	CAUSE	REMEDY
Burners will not	Misaligned spark electrodes.	Check ¯ame ignition and sensor electrode positioning.
ignite.		Adjust as needed.
	No gas at main burners.	Check gas line for air purge as necessary. After purging
		gas line of air, allow gas to dissipate for at least 5 min-
		utes before attempting to relight unit.
		Check gas valve.
	Water in gas line.	Drain water and install drip leg to trap water.
	No power to furnace.	Check power supply, fuses, wiring, and circuit breaker.
	No 24 v power supply to control circuit.	Check transformer. Transformers with internal overcur-
		rent protection require a cool down period before
		resetting.
	Miswired or loose connections	Check all wiring and wirenut connections.
	Burned-out heat anticipator in thermostat.	Replace thermostat.
	Broken thermostat wires.	Run continuity check. Replace wires, if necessary.
Inadequate heating.	Dirty air ®lter.	Clean or replace ®lter as necessary.
	Gas input to unit too low.	Check gas pressure at manifold. Clock gas meter for
		input. If too low, increase manifold pressure, or replace
		with correct ori®ces.
	Unit undersized for application.	Replace with proper unit or add additional unit.
	Restricted air¯ow.	Clean ®lter, replace ®lter, or remove any restrictions.
	Blower speed too low.	Use high speed tap, increase fan speed, or install op-
		tional blower, as suitable for individual units.
	Limit switch cycles main burners.	Check rotation of blower, thermostat heat anticipator set-
		tings, and temperature rise of unit. Adjust as needed.
	Too much outdoor air.	Adjust minimum position.
		Check economizer operation.
Poor ¯ame	Incomplete combustion (lack of combustion air)	Check all screws around ¯ue outlets and burner com-
characteristics.	results in:	partment. Tighten as necessary.
	Aldehyde odors, CO, sooting ¯ame, or ¯oating ¯ame.	Cracked heat exchanger.
		Over®red unit Ð reduce input, change ori®ces, or adjust
		gas line or manifold pressure.
		Check vent for restriction. Clean as necessary.
		Check ori®ce to burner alignment.
Burners will not	Unit is locked into Heating mode for a one minute	Wait until mandatory one minute time period has
turn off.	minimum.	elapsed or power to unit.

LEGEND AND NOTES FOR FIG. 48

		IMPORTANT:		Refer to unit wiring label for actual	unit
		wiring information.
AHA	Ð Adjustable Heat Anticipator		IFM	Ð Indoor (Evaporator) Fan Motor		Field Splice
BR	Ð Burner Relay		IGC	Ð Integrated Gas Unit
C	Ð Contactor, Compressor		LED	Controller		Marked Wire
CAP	Ð Capacitor			Ð Light Emitting Diode		Terminal (Marked)
CB	Ð Circuit Breaker		LPS	Ð Low-Pressure/Loss-of-Charge
CC	Ð Cooling Compensator			Switch		Terminal (Unmarked)
COMP	Ð Compressor Motor		LS	Ð Limit Switch
CR	Ð Control Relay		MGV	Ð Main Gas Valve		Terminal Block
D	Ð Diode		MTR	Ð Motor		Splice
EC	Ð Enthalpy Control		OAT	Ð Outdoor Air Thermostat
EPS	Ð Economizer Pressure Switch		OFM	Ð Outdoor-Fan Motor		Splice (Marked)
EQUIP	Ð Equipment		PL	Ð Plug Assembly
						Factory Wiring
FPT	Ð Freeze-Protection		QT	Ð Quadruple Terminal
	Thermostat		R	Ð Relay		Field Control Wiring
GND	Ð Ground		RS	Ð Rollout Switch		Field Power Wiring
GVR	Ð Gas Valve Relay		SAT	Ð Supply Air Thermostat		Accessory or Optional Wiring
HPS	Ð High-Pressure Switch		SEN	Ð Sensor		To indicate common potential
HS	Ð Hall Effect Sensor		TC	Ð Thermostat-Cooling		only, not to represent wiring
I	Ð Ignitor		TH	Ð Thermostat-Heating
IDM	Ð Induced-Draft Motor		TRAN Ð Transformer
IFC	Ð Indoor (Evaporator) Fan
	Contactor

NOTES:

1.If any of the original wire furnished must be replaced, it must be replaced with type 90 C wire or its equivalent.

2.Three-phase motors are protected under primary single phasing conditions.

3.Thermostat: HH07AT170, 172, 174 and P272-2783

Subbase: HH93AZ176, 178 and P272-1882, 1883

4.Set heat anticipator for ®rst stage at 0.14 amp, second stage at 0.2 amp.

5.Use copper conductors only.

6.TRAN is wired for 230 v unit. If unit is to be run with 208 v power supply, disconnect BLK wire from 230 v tap (RED) and connect to 200 v tap (BLU). Insulate end of 230 v tap.

7.When economizer assembly is installed move GRA wire from con- nection board (Y1) to GRA wire from PL6,5; move ORN wire from connection board (Y2) to ORN wire from PL6,9, on economizer assembly.

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