Functional Troubleshooting - Heat Controller DXM2 Application And Instruction Manual

Application, Operation, & Maintenance Manual

Functional Troubleshooting

CAUTION!
CAUTION! Do not restart
units without inspection and
remedy of faulting condition.
Equipment damage may
occur.
Fault Htg Clg Possible Cause
Main Power Problems
X
HP Fault Code 2
X
High Pressure
X
X
X
X
X
X
LP/LOC Fault-Code 3
Low Pressure/Loss of Charge X
X
LT1 Fault - Code 4
X
Water Low Temperature
X
X
X
LT2 Fault - Code 5
Low Air Temperature
X
X
X
Condensate Fault-Code 6
High Condensate Level
X
X
X
Over/Under Voltage-Code 7
(Auto Resetting)
X
X
Unit Performance
Sentinel-Code 8
Swapped Thermistor
X
Code 9
X
ECM Fault - Code 10
DXM2 UNIT CONTROLS
X Green status LED off
X Reduced or no water flow
in cooling
X
Water t emperature out of range in
cooling
Reduced or no air flow
in heating
Air t emperature out of range in
heating
X Overcharged with refrigerant
X
Bad HP switch
Frozen water heat exchanger
X Bad HPWS Switch
X Insufficient charge
Compressor pump down at start-
up
Reduced or no water flow
in heating
Inadequate anti-freeze level
Improper low temperature setting
(30°F vs 10°F)
Water t emperature out of range
X Bad thermistor
Reduced or no air flow
X
in cooling
X Air temperature out of range
Improper low temperature setting
X
(30°F vs 10°F)
X Bad thermistor
X Blocked drain
X Improper trap
X Poor drainage
X Moisture on sensor
Plugged air filter
X
X Restricted return air flow
X Under voltage
X Over voltage
Heating Mode LT2>125°F
Cooling Mode LT1>125°F OR
X
LT2< 40°F
X LT1 and LT2 swapped
X Blower does not operate
Blower operating with incorrect
airflow
24
Heat Controller, Inc.
Solution
Check Line Voltage circuit breaker and disconnect
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
Check pump operation or valve operation/setting
Check water flow adjust to proper flow rate
Bring water temp within design parameters
Check for dirty air filter and clean or replace
Check fan motor operation and airflow restrictions
Dirty air coil- construction dust etc.
Too high of external static. Check static vs blower table
Bring return air temp within design parameters
Check superheat/subcooling vs typical operating condition
table
Check switch continuity and operation - Replace
Thaw heat exchanger
Replace HPWS Switch
Check for refrigerant leaks
Check charge and start-up water flow
Check pump operation or water valve operation/setting
Plugged strainer or filter - clean or replace
Check water flow adjust to proper flow rate
Check antifreeze density with hydrometer
Clip LT1 jumper for antifreeze (10°F) use
Bring water temp within design parameters
Check temp and impedance correlation per chart
Check for dirty air filter and clean or replace
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
Too much cold vent air - bring entering air temp within
design parameters
Normal airside applications will require 30°F only
Check temp and impedance correlation per chart
Check for blockage and clean drain
Check trap dimensions and location ahead of vent
Check for piping slope away from unit
Check slope of unit toward outlet
Poor venting - check vent location
Check for moisture shorting to air coil
Replace air filter
Find and eliminate rectriction - increase return duct
and/or grille size
Check power supply and 24VAC voltage before and during
operation
Check power supply wire size
Check compressor starting. Need hard start kit?
Check 24VAC and unit transformer tap for correct power
supply voltage
Check power supply voltage and 24VAC before and during
operation.
Check 24VAC and unit transformer tap for correct power
supply voltage
Check for poor air flow or overcharged unit
Check for poor water flow, or air flow
Reverse position of thermistors
Check blower line voltage
Check blower low voltage wiring
Wrong unit size selection
Wrong unit family selection
Wrong motor size
Incorrect blower selection