Functional Troubleshooting
Performance Troubleshooting
Performance Troubleshooting
Htg Clg
Possible Cause
Solution
Insuf
¿
cient capacity/ Not
cooling or heating
X
X
Dirty
¿
lter
Replace or clean.
X
Reduced or no air
À
ow in heating
Check for dirty air
¿
lter and clean or replace.
Check fan motor operation and air
À
ow restrictions.
Too high of external static. Check static vs. blower table.
X
Reduced or no air
À
ow in cooling
Check for dirty air
¿
lter and clean or replace.
Check fan motor operation and air
À
ow restrictions.
Too high of external static. Check static vs. blower table.
X
X
Leaky duct work
Check supply and return air temperatures at the unit and at distant duct registers
if signi
¿
cantly different, duct leaks are present.
X
X
Low refrigerant charge
Check superheat and subcooling per chart.
X
X
Restricted metering device
Check superheat and subcooling per chart. Replace.
X
Defective reversing valve
Perform RV touch test.
X
X
Thermostat improperly located
Check location and for air drafts behind stat.
X
X
Unit undersized
Recheck loads & sizing. Check sensible clg. load and heat pump capacity.
X
X
Scaling in water heat exchanger
Perform scaling check and clean if necessary.
X
X
Inlet water too hot or too cold
Check load, loop sizing, loop back
¿
ll, ground moisture.
High Head Pressure
X
Reduced or no air
À
ow in heating
Check for dirty air
¿
lter and clean or replace.
Check fan motor operation and air
À
ow restrictions.
Too high of external static. Check static vs. blower table.
X
Reduced or no water
À
ow in cooling
Check pump operation or valve operation/setting.
Check water
À
ow. Adjust to proper
À
ow rate.
X
Inlet water too hot
Check load, loop sizing, loop back
¿
ll, ground moisture.
X
Air temperature out of range in heating
Bring return air temperature within design parameters.
X
Scaling in water heat exchanger
Perform scaling check and clean if necessary.
X
X
Unit overcharged
Check superheat and subcooling. Re-weigh in charge.
X
X
Non-condensables in system
Vacuum system and re-weigh in charge.
X
X
Restricted metering device.
Check superheat and subcooling per chart. Replace.
Low Suction Pressure
X
Reduced water
À
ow in heating.
Check pump operation or water valve operation/setting.
Plugged strainer or
¿
lter. Clean or replace.
Check water
À
ow. Adjust to proper
À
ow rate.
X
Water temperature out of range.
Bring water temperature within design parameters.
X
Reduced air
À
ow in cooling.
Check for dirty air
¿
lter and clean or replace.
Check fan motor operation and air
À
ow restrictions.
Too high of external static. Check static vs. blower table.
X
Air temperature out of range
Too much cold vent air? Bring entering air temperature within design parameters.
X
X
Insuf
¿
cient charge
Check for refrigerant leaks.
Low Discharge Air Temperature
in Heating
X
Too high of air
À
ow
Check fan motor speed selection and air
À
ow chart.
X
Poor performance
See ‘Insuf
¿
cient Capacity’
High humidity
X
Too high of air
À
ow
Check fan motor speed selection and air
À
ow chart.
X
Unit oversized
Recheck loads & sizing. Check sensible clg load and heat pump capacity.
Only Compressor Runs
X
X
Thermostat wiring
Check G wiring at heat pump. Jumper G and R for fan operation
X
X
Fan motor relay
Jumper G and R for fan operation. Check for Line voltage across BR contacts.
X
X
Check fan power enable relay operation (if present).
X
X
Fan motor
Check for line voltage at motor. Check capacitor.
X
X
Thermostat wiring
Check thermostat wiring at heat pump. Jumper Y and R for compressor operation
in test mode
Unit Doesn’t Operate
in Cooling
X
Reversing valve
Set for cooling demand and check 24VAC on RV coil and at CXM/DXM board.
If RV is stuck, run high pressure up by reducing water
À
ow and while operating
engage and disengage RV coil voltage to push valve.
X
Thermostat setup
Check for ‘O’ RV setup not ‘B’.
X
Thermostat wiring
Check O wiring at heat pump. Jumper O and R for RV coil ‘click’.
X
Thermostat wiring
Put thermostat in cooling mode. Check 24 VAC on O (check between C and
O); check for 24 VAC on W (check between W and C). There should be voltage
on O, but not on W. If voltage is present on W, thermostat may be bad or wired
incorrectly.
R e s i d e n t i a l S p l i t U n i t s - 6 0 H z P u r o n
®
R e v. : 6 D e c . , 2 0 1 1
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