Performance Troubleshooting - Heat Controller DXM2 Application And Instruction Manual

Application, Operation, & Maintenance Manual

Performance Troubleshooting

Symptom Htg Clg Possible Cause
X
X
Insufficient Capacity/
X
Not Cooling or Heating
X
Properly
X
X
X
X
X
X
High Head Pressure
X
X
X
X
X
X
Low Suction Pressure
X
Low Dischage Air X
Temperature in Heating
X
High Humidity
X
X
Only Compressor Runs
X
X
Unit Doesn't Operate in
Cooling
X
Modulating Valve
Troubleshooting
X Dirty filter
Rduced or no air flow
in heating
Reduced or no air flow
X
in cooling
X Leaky duct work
X Low refrigerant charge
X Restricted metering device
X Defective reversing va lve
X Thermostat improperly located
X Unit undersized
X Scaling in water heat exchanger
X Inlet water too hot or cold
Reduced or no air flow
in heating
X Reduced or no water flow
in cooling
X Inlet w ater too hot
Air temperature out of range in
heating
X Scaling in water heat exchanger
X Unit over charged
X Non-condensables insystem
X Restricted metering device
Reduced water flow
in heating
Water temperature out of range
Reduced air flow
X
in cooling
X Air temperature out of range
X Insufficient charge
Too high of air flow
Poor performance
X Too high of air flow
X Unit oversized
X Thermostat wiring
X Fan motor relay
X Fan motor
X Thermostat wiring
X Reversing Valve
X Thermostat setup
X Thermostat wiring
Improper output setting
No valve output signal
X
No valve operation
DXM2 UNIT CONTROLS
Solution
Replace or clean
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
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
Check supply and return air temperatures at the unit and at
distant duct registers if significantly different, duct leaks
are present
Check superheat and subcooling per chart
Check superheat and subcooling per chart - replace
Perform RV touch test
Check location and for air drafts behind stat
Recheck loads & sizing check sensible clg load and heat
pump capacity
Perform Scaling check and clean if necessary
Check load, loop sizing, loop backfill, ground moisture
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
Check pump operation or valve operation/setting
Check water flow adjust to proper flow rate
Check load, loop sizing, loop backfill, ground moisture
Bring return air temp within design parameters
Perform Scaling check and clean if necessary
Check superheat and subcooling - reweigh in charge
Vacuum system and reweigh in charge
Check superheat and subcooling per chart - replace
Check pump operation or water valve operation/setting
Plugged strainer or filter - clean or replace
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
Too high of external static - check static vs blower table
Too much cold vent air - bring entering air temp within
design parameters
Check for refrigerant leaks
Check fan motor speed selection and airflow chart
See "Insufficient Capacity"
Check fan motor speed selection and airflow chart
Recheck loads and sizing check sensible clg load and
heat pump capacity
Check G wiring at heat pump. Jumper G and R for fan
operation.
Jumper G and R for fan operation. Check for Line voltage
across blower relay contacts.
Check fan power enable relay operation (if present)
Check for line voltage at motor. Check capacitor
Check thermostat wiring at or DXM2. Put in Test Mode
and then jumper Y1 and W1 to R to give call for fan,
compressor and electric heat.
Set for cooling demand and check 24VAC on RV coil.
If RV is stuck, run high pressure up by reducing water flow
and while operating engage and disengage RV coil voltage
to push valve.
For DXM2 check for "O" RV setup not "B".
Check O wiring at heat pump. DXM2 requires call for
compressor to get RV coil "Click."
Verify the AO-2 jumper is in the 0-10V position
Check DC voltage between AO2 and GND. Should be O
when valve is off and between 3.3v and 10v when valve
is on.
Check voltage to the valve
Replace valve if voltage and control signals are present at
the valve and it does not operate
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Heat Controller, Inc.