23
GEO16-501.4
Table 23.1 - Troubleshooting
TROUBLESHOOTING
Fault
Mode
Possible Cause
Verify
Action
Htg Clg
Unit “short
cycles”
X
X
Dirty Air Filter
Check air filter
Replace, if necessary.
X
X
Thermostat location Check to see if thermostat is installed near a supply
air grill.
Relocate, if necessary.
X
X
Defective
compressor
overloads
Ensure that compressor is cool and overload has
had sufficient time to reset. Ohmmeter shows a
resistance across R & S terminals and OPEN or
infinite resistance between C & R or C & S terminals.
If windings are open or overload is faulty, replace
compressor.
X
X
Wiring and controls Examine all wiring points.
Tighten all wiring points.
Low pressure
cutout
X
Reduced water flow Check flow center operation
Troubleshoot flow center
Manually open water valve and measure water flow.
Adjust to proper flow rate.
Plugged water strainer or filter.
Replace or clean, if dirty.
X
Scaled or plugged
coaxial coil
Check temperature drop across coaxial coil.
Clean, if necessary.
X
Water supply too
cold
Verify GEO IN with temperature probe.
Verify loop sizing; verify that all air has been purged
from ground heat exchanger; bring water temperature
within design parameters.
X
Entering air too cold Measure return air, should be above 60ºF.
Bring return air temperature within design parameters.
X
Reduced air flow
Verify blower operation.
Troubleshoot blower operation.
Check air filter.
Replace or clean, if dirty.
Check for airflow restrictions in ducting system.
Address any ductwork airflow restrictions.
Check external static.
Check external static against blower table.
X
X
Low refrigerant
charge
Check for refrigerant leaks.
If leaks found, evacuate, repair and recharge to factory
recommended charge.
X
Plugged bi-flow
filter / drier
Verify that low pressure cut-out occurs in heating
mode and not in cooling mode.
Replace filter, if necessary.
X
X
Restricted TXV
Verify superheat and subcooling values.
Replace, if necessary.
X
X
Defective low
pressure switch
Monitor suction pressure while operating, verify low
pressure cut-out pressure (25 +/- 5 psig).
If defective, replace.
High pressure
cutout
X
Reduced water
flow
Check flow center operation.
Troubleshoot flow center.
Manually open water valve and measure water flow.
Adjust to proper flow rate.
Plugged water strainer or filter.
Replace or clean, if dirty.
X
Water supply too
hot
Verify GEO IN with temperature probe.
Verify loop sizing; bring water temperature within
design parameters.
X
Scaled or plugged
coaxial coil
Check temperature drop across coaxial coil.
Clean, if necessary.
X
Reduced or no air
flow in heating
Verify blower operation.
Troubleshoot blower operation.
Check air filter.
Replace or clean, if dirty.
Check for airflow restrictions in ducting system.
Address any ductwork airflow restrictions.
Check external static.
Check external static against blower table.
X
Air temperature out
of range
Measure return air, should be below 95ºF.
Bring return air temperature within design parameters.
X
X
Defective high
pressure switch
Monitor discharge pressure while operating, verify high
pressure cut-out pressure (600 +/- 25 psig).
Replace, if defective.
X
X
Overcharged with
refrigerant
Verify superheat and subcooling values.
Evacuate and recharge to factory recommended
charge.
X
X
Restricted TXV
Verify superheat and subcooling values.
Replace, if necessary.
X
X
Non-condensables
in system
Verify superheat and subcooling values.
Evacuate and recharge to factory recommended
charge.
X
Loss of control
signal
In cooling mode, verify 24VAC at RV coil and at REV
terminals.
If 24VAC exists, troubleshoot RV and coil.
If no control signal, troubleshoot thermostat signals.
