Install Instructions

58
IOM - HZH/HZV Series
Performance Troubleshooting (continued)
Symptom Htg Clg Possible Cause Solution
Insufficient Capacity/
XXDirty filter Replace or clean
Not Cooling or Heating
Reduced or no air flow
Check for dirty air filter and clean or replace
Properly
in heating
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
Reduced or no air flow
Check for dirty air filter and clean or replace
in cooling
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
XXLeaky duct work
Check supply and return air temperatures at the unit and at
distant duct registers if significantly different, duct leaks
are present
XXLow refrigerant charge Check superheat and subcooling per chart
XXRestricted metering device Check superheat and subcooling per chart - replace
X Defective reversing va lve Perform RV touch test
XXThermostat improperly located Check location and for air drafts behind stat
XXUnit undersized
Recheck loads & sizing check sensible cooling load and
heat
pump capacity
XXScaling in water heat exchanger Perform Scaling check and clean if necessary
XXInlet water too hot or cold Check load, loop sizing, loop backfill, ground moisture
High Head Pressure
X
Reduced or no air flow
Check for dirty air filter and clean or replace
in heating
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
X Reduced or no water flow Check pump operation or valve operation/setting
in cooling
Check water flow adjust to proper flow rate
X Inlet w ater too hot Check load, loop sizing, loop backfill, ground moisture
X
Air temperature out of range in
heating
Bring return air temp within design parameters
X Scaling in water heat exchanger Perform Scaling check and clean if necessary
XXUnit over charged Check superheat and subcooling - reweigh in charge
XXNon-condensables insystem Vacuum system and reweigh in charge
XXRestricted metering device Check superheat and subcooling per chart - replace
Low Suction Pressure
X
Reduced water flow
Check pump operation or water valve operation/setting
in heating
Plugged strainer or filter - clean or replace
Check water flow adjust to proper flow rate
XWater temperature out of range Bring water temp within design parameters
X
Reduced air flow
Check for dirty air filter and clean or replace
in cooling
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
XAir temperature out of range
Too much cold vent air - bring entering air temp within
design parameters
XXInsufficient charge Check for refrigerant leaks
Low Dischage Air
Temperature in Heating
XToo high of air flow Check fan motor speed selection and airflow chart
X Poor performance See “Insufficient Capacity”
High Humidity
XToo high of air flow Check fan motor speed selection and airflow chart
XUnit oversized
Only Compressor Runs
XXThermostat wiring
Check G wiring at heat pump. Jumper G and R for fan
operation.
XXFan motor relay
Jumper G and R for fan operation. Check for Line voltage
across blower relay contacts.
Check fan power enable relay operation (if present)
XXFan motor Check for line voltage at motor. Check capacitor
XXThermostat wiring
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.
Unit Doesn't Operate in
Cooling
X Reversing Valve
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.
X Thermostat setup
X Thermostat wiring
Check O wiring at heat pump. DXM2 requires call for
compressor to get RV coil “Click.”
X
X
Modulating Valve
Troubleshooting
X
Improper output setting
Verify the AO-2 jumper is in the 0-10V position
No valve operation
Check voltage to the valve
X
No valve output signal
Check DC voltage between AO2 and GND. Should be O
when valve is off and between 3.3v and 10v when valve
is on.
Replace valve if voltage and control signals are present at
the valve and it does not operate
For DXM2 check for “O” RV setup not “B”.
Recheck loads & sizing check sensible cooling load and
heat
pump capacity
Symptom Htg Clg Possible Cause Solution
Insufficient Capacity/
XXDirty filter Replace or clean
Not Cooling or Heating
Reduced or no air flow
Check for dirty air filter and clean or replace
Properly
in heating
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
Reduced or no air flow
Check for dirty air filter and clean or replace
in cooling
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
XXLeaky duct work
Check supply and return air temperatures at the unit and at
distant duct registers if significantly different, duct leaks
are present
XXLow refrigerant charge Check superheat and subcooling per chart
XXRestricted metering device Check superheat and subcooling per chart - replace
X Defective reversing va lve Perform RV touch test
XXThermostat improperly located Check location and for air drafts behind stat
XXUnit undersized
Recheck loads & sizing check sensible cooling load and
heat
pump capacity
XXScaling in water heat exchanger Perform Scaling check and clean if necessary
XXInlet water too hot or cold Check load, loop sizing, loop backfill, ground moisture
High Head Pressure
X
Reduced or no air flow
Check for dirty air filter and clean or replace
in heating
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
X Reduced or no water flow Check pump operation or valve operation/setting
in cooling
Check water flow adjust to proper flow rate
X Inlet w ater too hot Check load, loop sizing, loop backfill, ground moisture
X
Air temperature out of range in
heating
Bring return air temp within design parameters
X Scaling in water heat exchanger Perform Scaling check and clean if necessary
XXUnit over charged Check superheat and subcooling - reweigh in charge
XXNon-condensables insystem Vacuum system and reweigh in charge
XXRestricted metering device Check superheat and subcooling per chart - replace
Low Suction Pressure
X
Reduced water flow
Check pump operation or water valve operation/setting
in heating
Plugged strainer or filter - clean or replace
Check water flow adjust to proper flow rate
XWater temperature out of range Bring water temp within design parameters
X
Reduced air flow
Check for dirty air filter and clean or replace
in cooling
Check fan motor operation and airflow restrictions
Too high of external static - check static vs blower table
XAir temperature out of range
Too much cold vent air - bring entering air temp within
design parameters
XXInsufficient charge Check for refrigerant leaks
Low Dischage Air
Temperature in Heating
XToo high of air flow Check fan motor speed selection and airflow chart
X Poor performance See “Insufficient Capacity”
High Humidity
XToo high of air flow Check fan motor speed selection and airflow chart
XUnit oversized
Only Compressor Runs
XXThermostat wiring
Check G wiring at heat pump. Jumper G and R for fan
operation.
XXFan motor relay
Jumper G and R for fan operation. Check for Line voltage
across blower relay contacts.
Check fan power enable relay operation (if present)
XXFan motor Check for line voltage at motor. Check capacitor
XXThermostat wiring
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.
Unit Doesn't Operate in
Cooling
X Reversing Valve
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.
X Thermostat setup
X Thermostat wiring
Check O wiring at heat pump. DXM2 requires call for
compressor to get RV coil “Click.”
X
X
Modulating Valve
Troubleshooting
X
Improper output setting
Verify the AO-2 jumper is in the 0-10V position
No valve operation
Check voltage to the valve
X
No valve output signal
Check DC voltage between AO2 and GND. Should be O
when valve is off and between 3.3v and 10v when valve
is on.
Replace valve if voltage and control signals are present at
the valve and it does not operate
For DXM2 check for “O” RV setup not “B”.
Recheck loads & sizing check sensible cooling load and
heat
pump capacity