Comfort-Aire HBH Series 6-10 Tons - Manual (Page 44)

IOM Manual HBH SERIES Heat Controller, Inc.
43
Functional Troubleshooting
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.
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 flow
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'.
Performance
Troubleshooting
Htg Clg Possible Cause Solution
Insufficient capacity/ X X Dirty Filter Replace or clean
Not cooling or heating X 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
X 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
X X Leaky duct work
Check supply and return air temperatures at the unit and at
distant duct registers if significantly 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 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 Water 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
X X Unit Overcharged Check superheat and subcooling. Reweigh in charge
X X Non-condensables insystem Vacuum system and reweigh in charge
X X Restricted 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
X Water 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
X Air Temperature out of range
Too much cold vent air? Bring entering air temp within
design parameters
X X Insufficient charge Check for refrigerant leaks
Low discharge air
temperature in heating
X Too high of air flow Check fan motor speed selection and airflow chart
X Poor Performance See 'Insufficient Capacity'
High humidity X Too high of air flow Check fan motor speed selection and airflow chart
X Unit oversized
Recheck loads & sizing check sensible clg load and heat
pump capacity
X Thermostat wiring
Put thermostat in cooling mode. Check for 24VAC on O
(check between C and O); check for 24VAC 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.
Performance Troubleshooting