Heat Controller Functional Troubleshooting, DXM2 UNIT CONTROLS, Heat Controller, Inc, Fault

Application, Operation, & Maintenance Manual DXM2 UNIT CONTROLS Heat Controller, Inc.

Functional Troubleshooting

CAUTION!

CAUTION! Do not restart units without inspection and remedy of faulting condition. Equipment damage may occur.

Fault	Htg	Clg	Possible Cause	Solution
				Check Line Voltage circuit breaker and disconnect
Main Power Problems	X	X	Green status LED off	Check for line voltage between L1 and L2 on the contactor
				Check for 24VAC between R and C on DXM
				Check primary/secondary voltage on transformer
		X	Reduced or no water flow	Check pump operation or valve operation/setting
			in cooling	Check water flow adjust to proper flow rate
		X	Water t emperature out of range in	Bring water temp within design parameters
			cooling
				Check for dirty air filter and clean or replace
HP Fault Code 2	X		Reduced or no air flow	Check fan motor operation and airflow restrictions
High Pressure			in heating	Dirty air coil- construction dust etc.
				Too high of external static. Check static vs blower table
	X		Air t emperature out of range in	Bring return air temp within design parameters
			heating
	X	X	Overcharged with refrigerant	Check superheat/subcooling vs typical operating condition
				table
	X	X	Bad HP switch	Check switch continuity and operation - Replace
	X		Frozen water heat exchanger	Thaw heat exchanger
	X	X	Bad HPWS Switch	Replace HPWS Switch
LP/LOC Fault-Code 3	X	X	Insufficient charge	Check for refrigerant leaks
			Compressor pump down at start-	Check charge and start-up water flow
Low Pressure/Loss of Charge	X
			up
			Reduced or no water flow	Check pump operation or water valve operation/setting
	X			Plugged strainer or filter - clean or replace
			in heating
LT1 Fault - Code 4				Check water flow adjust to proper flow rate
Water Low Temperature	X		Inadequate anti-freeze level	Check antifreeze density with hydrometer
	X		Improper low temperature setting	Clip LT1 jumper for antifreeze (10°F) use
			(30°F vs 10°F)
	X		Water t emperature out of range	Bring water temp within design parameters
	X	X	Bad thermistor	Check temp and impedance correlation per chart
			Reduced or no air flow	Check for dirty air filter and clean or replace
		X		Check fan motor operation and airflow restrictions
			in cooling
				Too high of external static - check static vs blower table
LT2 Fault - Code 5		X	Air temperature out of range	Too much cold vent air - bring entering air temp within
				design parameters
Low Air Temperature
		X	Improper low temperature setting	Normal airside applications will require 30°F only
			(30°F vs 10°F)
	X	X	Bad thermistor	Check temp and impedance correlation per chart
	X	X	Blocked drain	Check for blockage and clean drain
	X	X	Improper trap	Check trap dimensions and location ahead of vent
				Check for piping slope away from unit
Condensate Fault-Code 6		X	Poor drainage	Check slope of unit toward outlet
				Poor venting - check vent location
High Condensate Level		X	Moisture on sensor	Check for moisture shorting to air coil
	X	X	Plugged air filter	Replace air filter
	X	X	Restricted return air flow	Find and eliminate rectriction - increase return duct
				and/or grille size
				Check power supply and 24VAC voltage before and during
				operation
	X	X	Under voltage	Check power supply wire size
Over/Under Voltage-Code 7				Check compressor starting. Need hard start kit?
				Check 24VAC and unit transformer tap for correct power
(Auto Resetting)
				supply voltage
				Check power supply voltage and 24VAC before and during
	X	X	Over voltage	operation.
				Check 24VAC and unit transformer tap for correct power
				supply voltage
Unit Performance	X		Heating Mode LT2>125°F	Check for poor air flow or overcharged unit
Sentinel-Code 8		X	Cooling Mode LT1>125°F OR	Check for poor water flow, or air flow
			LT2< 40°F
Swapped Thermistor	X	X	LT1 and LT2 swapped	Reverse position of thermistors
Code 9
	X	X	Blower does not operate	Check blower line voltage
				Check blower low voltage wiring
ECM Fault - Code 10			Blower operating with incorrect	Wrong unit size selection
			airflow
				Wrong unit family selection
				Wrong motor size
				Incorrect blower selection

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